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Presents an index of terms used in the December 2002 issue of 'Ailment Pharmacology Therapeutics.' Alpha-antagonist; Adenosine triphosphate; Ampicillin; Amoxicillin; Antibiotic prophylaxis; Anticonvulsants; Antidepressants; Bisacodyl; Cyclo-oxygenase; Cytosolic hepatic function; Colonic motility; Complementary therapy.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with substantial morbidity and mortality. Short-term exposure to fine particulate matter (PM 2.5 ) has been causally linked to higher risk of cardiovascular disease, but the association with atrial fibrillation (AF) is less clear., Methods: We conducted a time-stratified case-crossover study to estimate the association between short-term air pollution levels and risk of AF episodes. The episodes were identified among patients with paroxysmal AF and an intracardiac devices able to register and store AF episodes. We obtained air pollution and temperature data from fixed monitoring stations and used conditional logistic regression to quantify the association of PM 2.5 , particulate matter (PM 10 ), nitrogen dioxide (NO 2 ) and ozone (O 3 ) with onset of AF episodes, adjusting for temperature and public holidays."., Results: We analyzed 584 episodes of AF from 91 participants and observed increased risk of AF episodes with PM 2.5 levels for the 48-72 hours lag (OR 1.05; CI [1.01,1.09] per IQR)] and 72-96 hours (OR 1.05 CI [1.00,1.10] per IQR). Our results were suggestive of an association between O 3 levels and AF episodes during the warm season. We did not observe any statistically significant associations for PM 10 nor NO 2 ., Conclusion: Short-term increases in PM 2.5 in a low-pollution level environment were associated with increased risk of AF episodes in a population with intracardiac devices. Our findings add to the evidence of a potential triggering of AF by short-term increases in air pollution levels, well below the new WHO air quality guidelines., Competing Interests: G.W. reports a relationship with Health Effects Institute (Boston, MA) that includes: consulting or advisory and reports a relationship with Google, LLC (Mountain View, CA) that includes: consulting or advisory. The remaining authors declare that they have no conflicts of interest with regard to the content of this report., (Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The Environmental Epidemiology. All rights reserved.)

The Eastern Economic Corridor in Thailand is undergoing development, but industrial activities are causing serious air pollution. This study aimed to examine the effects of particulate matter (PM 10 ), fine particulate matter (PM 2.5 ), SO 2 , NO 2 , O 3 , and CO on outpatient department (OPD) visits and mortality with various causes in the Eastern Economic Corridor, Thailand between 2013 and 2019 using a case-crossover design and conditional Poisson model. The corresponding burden of disease due to air pollution exposure was calculated. A 1 µg/m 3 increase in the PM 10 was associated with significant increases in OPD visits for circulatory diseases (0.22, 95% CI 0.01, 0.34), respiratory diseases (0.21, 95% CI 0.13, 0.28), and skin and subcutaneous tissue diseases (0.18, 95% CI 0.10, 0.26). By contrast, a 1 µg/m 3 increase in the PM 10 was associated with significant increases in mortality from skin and subcutaneous tissue diseases (0.79, 95% CI 0.04, 1.56). A 1 µg/m 3 increase in PM 2.5 was associated with significant increases in mortality from circulatory diseases (0.75, 95% CI 0.20, 1.34), respiratory diseases (0.82, 95% CI 0.02, 1.63), and skin and subcutaneous tissue diseases (2.91, 95% CI 0.99, 4.86). The highest OPD burden was for circulatory diseases. Respiratory effects were attributed to PM 10 exceeding the national ambient air quality standards (NAAQS) of Thailand (120 μg/m 3 ). The highest morbidity burden was for skin and subcutaneous tissue diseases attributed to PM 2.5 concentrations that exceeded the NAAQs (50 μg/m 3 ). PM pollution in the EEC could strongly contribute to OPD visits and morbidity from various diseases. Preventing PM 10 concentrations from being higher than 60 µg/m 3 could decrease OPD visits by more than 33,265 and 29,813 for circulatory and respiratory diseases, respectively. Our study suggests that such pollution increases the risks of OPD visits and mortality in various causes in the Thai EEC. Reducing the ambient air pollution concentration of NAAQSs in Thailand could reduce the health effect on the Thai population.

Background: The associations of ambient temperature with acute myocardial infarction (AMI) have seldom been examined based on the time of symptom onset., Methods: We conducted a time-stratified case-crossover study among 1,046,773 eligible AMI patients from 2,093 hospitals in 324 Chinese cities from January 1, 2015 to June 30, 2021, after excluding those transferred from other hospitals or having not reported the time of symptom onset. Hourly exposure to ambient temperature was calculated as multiple moving 24-h averages (days) before hourly onset of AMI symptoms. Conditional logistic regression and distributed lag non-linear models with a duration of 0-21 days were used to estimate the cumulative associations of non-optimum temperature with AMI onset and the corresponding disease burden nationally. Subgroup analyses by region and period were conducted. Specifically, cities with and without centralized heating system were classified into heating and non-heating regions, respectively. The whole year in heating region was divided into heating and non-heating periods based on the duration of centralized heating in each city., Findings: Almost monotonically increasing risks were observed for both overall AMI and its two subtypes when ambient temperature declined. The effects of extremely low temperature occurred immediately on the concurrent day, and lasted up to almost 3 weeks. The excess risks of AMI onset associated with non-optimum ambient temperatures were observed during the whole year in the non-heating region and non-heating period in the heating region, but not during heating period. Specifically, odds ratios of AMI onset associated with extremely low temperature cumulated over 0-21 days were 1.24 (95% CI: 1.13-1.37), 1.46 (95% CI: 1.20-1.76), and 1.62 (95% CI: 1.46-1.81) in the heating region during non-heating period, in the non-heating region during winter and non-winter period, respectively. The heat effects on AMI onset were very modest and transient. Totally, 13.26% of AMI cases could be attributable to non-optimum temperatures nationally. The burden of AMI attributable to non-optimum temperature was much smaller in heating region than in non-heating region. Somewhat stronger effects were observed in females and patients aged older than 65., Interpretation: This nationwide study provided robust evidence that non-optimum ambient temperature may significantly trigger AMI onset, and for the first time estimated the disease burden after accounting for spatial and seasonal heterogeneity. Centralized heating might substantially mitigate AMI burden due to non-optimum temperature., Funding: Shanghai International Science and Technology Partnership Project, National Natural Science Foundation of China, Talent Training Program of Zhongshan Hospital, Fudan University., Competing Interests: All authors declare no competing interests., (© 2022 The Author(s).)

[Display omitted] • Limited evidence on short-term exposure to PM 2.5 and under-5 mortality in China. • A national case-crossover study and use of satellite-based exposure model. • PM 2.5 was associated a 1.15% (95%CI: 0.65%, 1.65%) increase in under-5 mortality. • Cause-specific mortality from diarrhea, pneumonia, digestive diseases, and preterm birth. • Supra-linear concentration-response curve with steeper slope in lower concentrations. Under-5 mortality rate is an important indicator in Millennium Development Goals and Sustainable Development Goals. To date, no nationally representative studies have examined the effects of fine particulate matter (PM 2.5) air pollution on under-5 mortality. To investigate the association of short-term exposure to PM 2.5 with under-5 mortality from total and specific causes in China. We used the national Maternal and Child Health Surveillance System to identify under-5 mortality cases during the study period of 2009 to 2019. We adopted a time-stratified case-crossover study design at the individual level to capture the effect of short-term exposure to daily PM 2.5 on under-5 mortality, using conditional logistic regression models. A total of 61,464 under-5 mortality cases were included. A 10 μg/m3 increase in concentrations of PM 2.5 on lag 0–1 d was significantly associated with a 1.15% (95%confidence interval: 0.65%, 1.65%) increase in under-5 mortality. Mortality from diarrhea, pneumonia, digestive diseases, and preterm birth were significantly associated with exposure to PM 2.5. The effect estimates were larger for neonatal mortality (<28 days), female children, and in warm seasons. We observed steeper slopes in lower ranges (<50 μg/m3) of the concentration-response curve between PM 2.5 and under-5 mortality, and positive associations remained below the 24-h PM 2.5 concentration limit recommended by WHO Air Quality Guidelines and China Air Quality Standards. This nationwide case-crossover study in China demonstrated that acute exposure to PM 2.5 may significantly increase the risk of under-5 mortality, with larger effects for neonates, female children, and during warm seasons. Relevant control strategies are needed to remove this roadblock to achieving under-5 mortality targets in developing countries. [ABSTRACT FROM AUTHOR]

Air pollution could be a risk factor for the development of pterygium. This study aimed to investigate the potential associations between outpatient visits for pterygium and air pollutants. Using a time-stratified case-crossover design, the data of 3017 outpatients with pterygium visiting an eye center in Hangzhou, China, and the air pollution data of the Environmental Protection Department of Zhejiang Province between July 1, 2014, and November 30, 2019, were examined. The relationships between the air pollutants nitrogen dioxide (NO 2), sulfur dioxide (SO 2), ozone, and fine particulate matter (PM) with median aerometric diameter <2.5 μm (PM 2.5) and <10 μm (PM 10) and outpatient visits for primary pterygium were assessed using single- and multiple-pollutant models. Significant associations between outpatient visits for pterygium and air pollutants (PM 2.5 , PM 10 , SO 2 , and NO 2) were observed. Younger patients were found to be more sensitive to air pollution. Interestingly, the younger female patients with pterygium were more vulnerable to PM 2.5 exposure during the warm season, while the younger male patients with pterygium were more sensitive to NO 2 during the cold season. Significant effects were also observed between the pterygium outpatients and PM 2.5 (odds ratio [OR] = 1.06, P = 0.02), PM 10 (OR = 1.04, P = 0.01), and SO 2 (OR = 1.26, P = 0.01) during the warm season, as well as NO 2 (OR = 1.06, P = 0.01) during the cold season. Our study provides evidence that outpatient visits for pterygium are positively associated with increases in the air pollutants PM 2.5 , PM 10 , SO 2 , and NO 2 , revealing the important role of air pollution in the occurrence and development of pterygium. [Display omitted] • Air pollutants are in significant associations with outpatient visits for pterygium. • Younger pterygium patients are more sensitive to air pollution. • The female pterygium patients are more vulnerable to PM 2.5 during the warm season. • The male pterygium patients are more sensitive to NO 2 during the cold season. [ABSTRACT FROM AUTHOR]

The Electric Bike (EB) has become an ideal mode of transportation because of its simple operation, convenience, and because it is time saving, economical and environmentally friendly. However, electric bicycle road-traffic injuries (ERTIs) have become a road-traffic safety problem that needs to be solved urgently, bringing a huge burden to public health. In order to provide basic data and a theoretical basis for the prevention and control of ERTIs in Shantou, mixed research combining a case-control study and a case-crossover study was carried out to investigate the cycling behavior characteristics and injury status of EB riders in Shantou city, and to explore the influencing factors of ERTI. The case-control study selected the orthopedic inpatient departments of three general hospitals in Shantou. The case-crossover study was designed to assess the effect of brief exposure on the occurrence of ERTIs, in which each orthopedic inpatient serves as his or her own control. Univariable and multivariable logistic regressions were used to examine the associated factors of ERTIs. In the case-control study, multivariable analysis showed that chasing or playing when cycling, finding the vehicle breakdown but continuing cycling, not wearing the helmet, and retrograde cycling were risk factors of ERTIs. Compared with urban road sections, suburb and township road sections were more likely to result in ERTIs. Astigmatism was the protective factor of ERTI. The case-crossover study showed that answering the phone or making a call and not wearing a helmet while cycling increased the risk of ERTIs. Cycling in the motor-vehicle lane and cycling on the sidewalk were both protective factors. Therefore, the traffic management department should effectively implement the policy about wearing a helmet while cycling, increasing the helmet-wearing rate of EB cyclists, and resolutely eliminate illegal behaviors such as violating traffic lights and using mobile phones while cycling. Mixed lanes were high-incidence road sections of ERTIs. It was suggested that adding people-non-motor-vehicles/motor vehicles diversion and isolation facilities in the future to ensure smooth roads and safety would maximize the social economic and public health benefits of EB.

The causal effects of vaccines on Kawasaki disease (KD) remain elusive. We aimed to examine the association between vaccines administered during infancy and the development of KD in Japan. We conducted a multicenter prospective case-control study using questionnaires and compared the vaccination status of infants (age: 6 weeks to 9 months) who developed KD (KD group; n = 102) and those who did not develop KD (non-KD group; n = 139). Next, we performed a case-crossover study of 98 cases in the KD group and compared the status of vaccinations between the case and control periods. We also compared the incidence of KD in children for each 5-year period before and after the addition of new vaccines (2012–2013) using data from the Nationwide Survey of KD. In the case-control study, the vaccination status of the KD and control groups did not differ to a statistically significant extent. Multivariable analysis of the vaccination status and patient backgrounds showed no significant association between vaccination and KD development. In the case-crossover study, the status of vaccinations during the case and control periods did not differ to a statistically significant extent. In the analysis of data from the Nationwide Survey of KD, the incidence of KD in children of ages subject to frequent vaccination showed no significant increases in the latter five years, 2014–2018. Based on these prospective analyses, we confirmed that vaccination in early infancy did not affect the risk of KD. [ABSTRACT FROM AUTHOR]

Objective: Our objectives were to study anger as a trigger of acute myocardial infarction (MI) and to explore potential effect modification by usual behavioral patterns related to hostility.Methods: This study was a case-crossover study within the Stockholm Heart Epidemiology Program. Exposure in the period immediately preceding MI was compared with exposure during a control period for each case. From April 1993 to December 1994, 699 patients admitted to coronary care units in Stockholm County were interviewed.Results: During a period of 1 hour after an episode of anger, with an intensity of at least "very angry," the relative risk of MI was 9.0 (95% CI, 4.4-18.2). In patients with premonitory symptoms, the time of disease initiation may be misclassified. When restricting the analyses to those without such symptoms, the trigger risk was 15.7 (95% CI, 7.6-32.4). The possibility of examining effect modification was limited by a lack of statistical power (eight exposed cases). Results of the analyses suggested, however, an increased trigger effect among subjects reporting nonhostile usual behavior patterns, nonovert strategies of coping with aggressive situations (not protesting when being treated unfairly), and nonuse of beta-blockers.Conclusions: The hypothesis that anger may trigger MI is further supported, with an increased risk lasting for approximately 1 hour after an outburst of anger. It is suggested that the trigger risk may be modified by personal behavior patterns. [ABSTRACT FROM AUTHOR]

Aims: The incidence of acute aortic dissection (AAD) has been shown to have seasonal variation, but whether this variation can be explained by non-optimum ambient temperature and temperature change between neighbouring days (TCN) is not clear., Methods and Results: We performed a time-stratified case-crossover study in the Registry of Aortic Dissection in China covering 14 tertiary hospitals in 11 cities from 2009 to 2019. A total of 8182 cases of AAD were included. Weather data at residential address were matched from nearby monitoring stations. Conditional logistic regression model and distributed lag nonlinear model were used to estimate the associations of daily temperature and TCN with AAD, adjusting for possible confounders. We observed an increase of AAD risk with lower temperature cumulated over lag 0-1 day and this association became statistically significant when daily mean temperature was below 24°C. Relative to the referent temperature (28°C), the odds ratios (ORs) of AAD onset at extremely low (-10°C) and low (1°C) temperature cumulated over lag 0-1 day were 2.84 [95% confidence interval (CI): 1.69, 4.75] and 2.36 (95% CI: 1.61, 3.47), respectively. A negative TCN was associated with increased risk of AAD. The OR of AAD cumulated over lag 0-6 days was 2.66 (95% CI: 1.76, 4.02) comparing the extremely negative TCN (-7°C) to no temperature change. In contrast, a positive TCN was associated with reduced AAD risk., Conclusion: This study provides novel and robust evidence that low ambient temperature and temperature drop between neighbouring days were associated with increased risk of AAD onset., Key Question: Incidence of acute aortic dissection (AAD) was reported to have seasonal trends, but it remains unclear whether non-optimum ambient temperature and temperature change between neighbouring days (TCN) is associated with AAD onset., Key Finding: Daily mean temperature lower than 24°C was significantly associated with increased risk of AAD at lag 0-1 day. A negative TCN (temperature drop) was associated with increased risk of AAD, whereas a positive TCN was associated with decreased risk., Take Home Message: This multi-centre, case-crossover study provides novel and robust evidence that low ambient temperature and temperature drop between neighbouring days were associated with increased AAD risk., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Most epidemiologic studies fail to capture the impact of spatiotemporal fluctuations in traffic on exposure to traffic-related air pollutants in the near-road population. Using a case-crossover design and the Research LINE source (R-LINE) dispersion model with spatiotemporally resolved highway traffic data, we quantified associations between primary pollutants generated by highway traffic-particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5), oxides of nitrogen (NOx), and black carbon (BC)-and daily nonaccidental, respiratory, cardiovascular, and cerebrovascular mortality among persons who had resided within 1 km (0.6 mile) of major highways in the Puget Sound area of Washington State between 2009 and 2013. We estimated these associations using conditional logistic regression, adjusting for time-varying covariates. Although highly resolved modeled concentrations of PM2.5, NOx, and BC from highway traffic in the hours before death were used, we found no evidence of an association between mortality and the preceding 24-hour average PM2.5 exposure (odds ratio = 0.99, 95% confidence interval: 0.96, 1.02) or exposure during shorter averaging periods. This work did not support the hypothesis that mortality risk was meaningfully higher with greater exposures to PM2.5, NOx, and BC from highways in near-road populations, though we did incorporate a novel approach to estimate exposure to traffic-generated air pollution based on detailed traffic congestion data., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose : To investigate state- and trait-like risk factors leading to childhood eye injuries controlling for the between-subject difference. This study measured socioeconomic, environmental, behavioral, and injury event characteristics to identify eye injury protective and risk factors. Methods : A retrospective case-crossover study including patients aged 0-18 years old (y.o.) with severe eye trauma treated at the Canton Hospital Zenica between 2011 and 2017 was conducted. One case time point was at the time of injury, and two control time points 1 month before the injury and a month before the survey. Results : Of 36 patients meeting the criteria, four were excluded, resulting in 32 cases and 64 controls. The mean age was 10.79 in males (77.8%) and 11 y.o. in females (22.2%). In univariate GEE logistic regression unusual activity had odds of 17.25 (95%CI = 6.97, 42.70), working/chores vs.running activity odds of 6.60 (95%CI = 1.71, 25.46), very active level vs.an intermediate child activity level odds of 5.26 (1/0.19, 95%CI = 1.75, 16.67) no supervision odds of 2.63 (1/0.38, 95%CI = 1.45, 4.76) and less than 7 hours of sleep odds of 4.69 (95%CI = 1.06, 20.77) of sustaining an eye injury. Using the quasi-likelihood approach and QICu as an indicator, the best model yielded odds of getting eye injured = 0.59 + 19.35*engaging in unusual activity+0.21*supervised by an adult person+0.84*playing+3.04*working within the households+0.22*other activity. Conclusions : Giving the best model to predict injuries, the combined strategies of teaching, modifying the environment, and the watchful supervision present a preventive triad that needs to be further explored and encouraged in practice.

Background: Opioid-overdose deaths are associated with poisoning with prescription and illicit opioids in the USA. In contrast, opioid-related deaths (ORDs) in the UK often involve drugs and substances of misuse, and may not be associated with a high dose of prescribed opioids. This study aimed to investigate the association between prescribed opioid dose and ORDs in UK primary care., Methods: This case-crossover study used the Clinical Practice Research Datalink and death registration between 2000 and 2015 to identify ORDs. Daily oral morphine equivalent (OMEQ) dose was measured within a 90 day focal window before ORD and three earlier reference windows. Conditional logistic regression models assessed the adjusted odds ratio (aOR) and 95% confidence interval (95% CI) comparing daily OMEQ dose greater than 120 mg in the focal window against the reference windows., Results: Of the 232 ORDs, 62 (26.7%) were not prescribed opioids in the year before death. Of the remaining 170 cases, 50 (29.4%) were never prescribed a daily OMEQ dose greater than 50 mg. Daily OMEQ doses over 120 mg (aOR 2.20; 95% CI: 1.06-4.56), co-prescribing gabapentinoids (aOR 2.32; 95% CI: 1.01-5.33), or some antidepressants (aOR 3.03; 95% CI: 1.02-9.04) significantly increased the risk of ORD., Conclusions: Daily OMEQ dose greater than 120 mg and the concomitant use of psychotropic medicines were related to ORDs in the UK. Prescribers should cautiously avoid prescribing opioids with a daily OMEQ dose greater than 120 mg day -1 and the combination of opioids and gabapentinoids, even with low opioid doses., (Copyright © 2021 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Air pollution has already become a serious public health concern worldwide, while evidence for the association between air pollution and digestive disease is not consistent. To examine the association between air pollution and peptic ulcer bleeding (PUB). We performed a time-stratified case-crossover study among 1,246,270 gastroscopy records in Zhejiang, China from January 1st, 2013 to June 30th, 2019. Individual exposure to air pollution for each subject was estimated by using data from 55 fixed-sites with an inverse distance weighted method. Conditional logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (95% CIs) for PUB associated with an interquartile range (IQR) increase in air pollution on the entire population. Subgroup analyses were performed for season, age and sex. Totally 3543 patients diagnosed with PUB were included in the analyses. Significant associations were observed between NO 2 , CO and PM 2.5 and the risk of PUB. The effect was observed strongest measured as lag 06 and an IQR increase of 7-day moving average concentrations of NO 2 resulted in a 24.0% increase of getting PUB (95% CI: 2.6%–50.0%). Our findings strengthen the hypothesis that short-term air pollution exposure has adverse health effects on digestive system. • Air pollution has adverse health effects on respiratory and cardiovascular systems. • The effects of air pollutants on peptic ulcer bleeding are still unclear. • Short-term exposure to some air pollutants contribute to peptic ulcer bleeding. [ABSTRACT FROM AUTHOR]

Despite contributing to the majority of ambient fine particles (PM 2.5), PM 1 (particulate matter [PM] with aerodynamic diameter ≤1 μm) remains poorly studied in terms of its acute effects on cardiovascular diseases (CVDs) in China. This study aims to evaluate the short-term associations of size-specific PMs (i.e., PM 1 , PM 2.5 , and PM 10) exposures with hospital admissions for CVDs in a southern Chinese metropolis. We collected 5,969 records of hospital admissions for CVDs and daily average concentrations of air pollutants and weather conditions in Shenzhen from January 1st 2015 to December 31st 2017. We adopted a time-stratified case-crossover design and conditional logistic regression models to assess short-term associations between size-specific PMs and CVD hospitalizations along different exposure days. During the study period, annual average concentrations of PM 1 , PM 2.5 , and PM 10 were 18.7, 27.8, and 45.4 μg/m3, respectively. Compared to PM 2.5 and PM 10 , PM 1 exhibited a generally stronger association with CVD hospitalizations. Hospital admissions for CVDs increased by 6.7% (95% confidence interval: 1.2–12.5%), 4.5% (0.4–8.7%), and 3.4% (0.5–6.3%), corresponding to per 10-μg/m3 rise in exposure to PM 1 , PM 2.5 , and PM 10 at lag 03 days. In our stratified analyses by CVD sub-causes, size-specific PMs showed consistent effects on hypertension but no evident association with ischemic heart disease (IHD) and stroke. Seasonal analysis revealed significantly larger PM-associated risks among IHD patients in cold months (October–March). Nevertheless, in warm months (April–September), the older group (aged 65+ years) was more prone to adverse effects of PM 1 exposure at lag 0 day. Short-term exposure to size-specific PMs, PM 1 in particular, may trigger incidences of CVD hospitalization. To effectively mitigate adverse effects of particulate pollution, evidence-based PM 1 standards should be developed as well in Chinese less-polluted megacities. [Display omitted] • PM 1 exhibited relatively stronger effects on CVDs than PM 2.5 and PM 10. • Detected impacts from size-specific PMs on hypertension but not IHD and stroke. • PM-associated effects on IHD were only identified in cold months. [ABSTRACT FROM AUTHOR]

Background: Climate change is increasing the risks of injuries, diseases, and deaths globally. However, the association between ambient temperature and renal diseases has not been fully characterized. This study aimed to quantify the risk and attributable burden for hospitalizations of renal diseases related to ambient temperature., Methods: Daily hospital admission data from 1816 cities in Brazil were collected during 2000 and 2015. A time-stratified case-crossover design was applied to evaluate the association between temperature and renal diseases. Relative risks (RRs), attributable fractions (AFs), and their confidence intervals (CIs) were calculated to estimate the associations and attributable burden., Findings: A total of 2,726,886 hospitalizations for renal diseases were recorded during the study period. For every 1°C increase in daily mean temperature, the estimated risk of hospitalization for renal diseases over lag 0-7 days increased by 0·9% (RR = 1·009, 95% CI: 1·008-1·010) at the national level. The associations between temperature and renal diseases were largest at lag 0 days but remained for lag 1-2 days. The risk was more prominent in females, children aged 0-4 years, and the elderly ≥ 80 years. 7·4% (95% CI: 5·2-9·6%) of hospitalizations for renal diseases could be attributable to the increase of temperature, equating to 202,093 (95% CI: 141,554-260,594) cases., Interpretation: This nationwide study provides robust evidence that more policies should be developed to prevent heat-related hospitalizations and mitigate climate change., Funding: China Scholarship Council, and the Australian National Health and Medical Research Council., Competing Interests: We declare no competing interests., (© 2021 The Author(s).)

Background: Case-crossover studies have been widely used in various fields including pharmacoepidemiology. Vines and Farrington indicated in 2001 that when within-subject exposure dependency exists, conditional logistic regression can be biased. However, this bias has not been well studied., Methods: We have extended findings by Vines and Farrington to develop a weighting method for the case-crossover study which removes bias from within-subject exposure dependency. Our method calculates the exposure probability at the case period in the case-crossover study which is used to weight the likelihood formulae presented by Greenland in 1999. We simulated data for the population with a disease where most patients receive a cyclic treatment pattern with within-subject exposure dependency but no time trends while some patients stop and start treatment. Finally, the method was applied to real-world data from Japan to study the association between celecoxib and peripheral edema and to study the association between selective serotonin reuptake inhibitor (SSRI) and hip fracture in Australia., Results: When the simulated rate ratio of the outcome was 4.0 in a case-crossover study with no time-varying confounder, the proposed weighting method and the Mantel-Haenszel odds ratio reproduced the true rate ratio. When a time-varying confounder existed, the Mantel-Haenszel method was biased but the weighting method was not. When more than one control period was used, standard conditional logistic regression was biased either with or without time-varying confounding and the bias increased (up to 8.7) when the study period was extended. In real-world analysis with a binary exposure variable in Japan and Australia, the point estimate of the odds ratio (around 2.5 for the association between celecoxib and peripheral edema and around 1.6 between SSRI and hip fracture) by our weighting method was equal to the Mantel-Haenszel odds ratio and stable compared with standard conditional logistic regression., Conclusion: Case-crossover studies may be biased from within-subject exposure dependency, even without exposure time trends. This bias can be identified by comparing the odds ratio by the Mantel-Haenszel method and that by standard conditional logistic regression. We recommend using our proposed method which removes bias from within-subject exposure dependency and can account for time-varying confounders., (© 2021. The Author(s).)

• Ambient temperature was linearly associated intentional homicide with seven days lag. • The association was significant in Chicago and New York but not in other cities. • The association was stronger for cases that happened during the hot season, in the nighttime and on the street. There has been an increasing interest in the association between ambient temperature and violence and crime, in the context of global warming. We aimed to evaluate the association between daily ambient temperature and intentional homicide—a proxy for overall inter-personal violence. We collected daily weather and crime data from 9 large US cities (Chicago, Detroit, Fort Worth, Kansas City, Los Angeles, Louisville, New York, Tucson and Virginia Beach) from 2007 to 2017. A time-stratified case-crossover design was used. The associations were quantified by conditional logistic regression with distributed lag models, adjusting for relative humidity, precipitation and effects of public holidays. City-specific odds ratios (OR) were used to calculate the attributable fractions in each city. Based on 19,523 intentional homicide cases, we found a linear temperature-homicide association. Every 5 °C increase in daily mean temperature was associated with a 9.5% [95% confidence interval (CI): 4.3–15.0%] and 8.8% (95% CI: 1.5–16.6%) increase in intentional homicide over lag 0–7 days in Chicago and New York, respectively. The association was not statistically significant in the other seven cities and seemed to be stronger for cases that happened during the hot season, at night (18:00–06:00) and on the street. During the study period, 8.7% (95%CI: 4.3–12.7%) and 7.1% (95% CI: 1.4–12.0%) intentional homicide cases could be attributed to temperatures above city-specific median temperatures, corresponding to 488 and 316 excess cases in Chicago and New York, respectively. Our study suggests that the interpersonal violence might increase with temperature in some US cities. We also provide some insights into the mechanisms and targeted prevention strategies for heat-related violence. [ABSTRACT FROM AUTHOR]

The etiology of osteoarthritis (OA) pain exacerbations is not well understood. The purpose of this study is to evaluate the association of heel height and duration of wearing shoes with higher heels with pain exacerbations in people with hip OA. Eligible participants with symptomatic hip OA were instructed to complete online questionnaires every 10 days over a 90-day follow-up period. They were required to complete the questionnaire whenever they were experiencing hip pain exacerbation. Of 252 participants recruited, 137 (54.4%) contributed both case and control period data, and were included in the analysis. Wearing shoes with a heel height ≥ 2.5 cm during the past 24 h was associated with lower odds of pain exacerbations (OR: 0.54, 95% CI: 0.30 to 0.99). A longer duration (>6 h) of wearing shoes with heel height ≥ 2.5 cm was also associated with a lower risk of hip pain exacerbations (p for linear trend = 0.003). Wearing shoes with heel height ≥ 2.5 cm and longer duration in the past 24 h may be protective against hip pain exacerbations in people with symptomatic hip OA. Given the observational study nature, it would be prudent for this to be replicated in an independent data set. [ABSTRACT FROM AUTHOR]

Ambient PM 2.5 has been identified as the top leading cause of risk-attributable deaths worldwide, particularly in China. Evidence suggested that PM 1 contributed the most majority of PM 2.5 concentrations in Chinese cities. However, epidemiologic knowledge to date is of wide lack regarding PM 1 -associated health effects. We collected daily records of all-cause emergency department visits (EDVs) and ground measurements of ambient air pollutants and meteorological factors in Guangzhou and Shenzhen, China, 2015–2016. Case-crossover design and conditional logistic regression models were used to comparatively assess the short-term effects of ambient PM 1 , PM 2.5 , and PM 10 on EDVs. Stratified analyses by gender, age and season were performed to identify vulnerable groups and periods. PM 1 , PM 2.5 and PM 10 were all significantly associated with increased EDVs in both cities. Population risks for EDVs increased by 2.2% [95% confidence interval, 1.8 to 2.6] in Guangzhou and 1.7% [1.0 to 2.4] in Shenzhen, for a 10 μg/m3 rise in PM 1 at lag 0–1 days and lag 0–4 days, respectively. Relatively lower risks were found to be associated with PM 2.5 and PM 10. PM-EDVs associations exhibited no gender differences, but varied across age groups. Compared with adults and the elderly, children under 14 years-of-age suffered higher PM-induced risks. Results from both cities suggested greatly significant effect modification by season, with consistently stronger PM-EDVs associations during cold months. Our study added comparative evidence for increased EDVs risks associated with short-term exposures to ambient PM 1 , PM 2.5 and PM 10. Besides, PM-associated effects were significantly stronger among children and during cold months. • Comparative analysis of EDVs risks associated with PM 1 , PM 2.5 and PM 10. • PM 1 exhibited relatively stronger effects on EDVs than PM 2.5 and PM 10. • PM-associated effects were stronger among children and during cold months. [ABSTRACT FROM AUTHOR]

Although residing in lower surrounding greenness and transient exposure to air pollution are independently associated with higher risk of adverse health outcomes, little is known about their interactions. We examine whether residential neighborhood greenness modifies the short-term association between air pollution and respiratory mortality among the participants of Chinese Elderly Health Service Cohort in Hong Kong. We estimated residential surrounding greenness by measuring satellite-derived normalized difference vegetation index (NDVI) from Landsat within catchments of residential addresses of participants who died of respiratory diseases between 1998 and 2011. We first dichotomized NDVI into low and high greenness and used a time-stratified case-crossover approach to estimate the percent excess risk of respiratory mortality associated with fine particulate matter (PM 2.5), respirable particulate matter (PM 10), nitrogen dioxide (NO 2), and ozone (O 3). We further classified NDVI into greenness quartiles and introduced an interaction term between air pollution and the assigned median values of the NDVI quartiles into the models to assess the trend of greenness modification on the air pollution and respiratory mortality associations. Among 3159 respiratory deaths during the follow-up, 2058 were from pneumonia and 947 from chronic obstructive pulmonary disease. Elders living in the low greenness areas were associated with a higher risk of pneumonia mortality attributed to NO 2 (p = 0.049) and O 3 (p = 0.025). The mortality risk of pneumonia showed a decreasing trend for NO 2 (p for trend = 0.041), O 3 (p for trend = 0.006), and PM 2.5 (p for trend = 0.034) with greenness quartiles increasing from Quartile 1 (lowest) to Quartile 4 (highest). Our findings suggest that elders living in higher greenness areas are less susceptible to pneumonia mortality associated with air pollution, which provides evidence for optimizing allocation, siting, and quality of urban green space to minimize detrimental health effects of air pollution. Image 1 • We examined the interaction between greenness and air pollution on respiratory mortality among HK elders. • Elders residing in greater greenness areas are less susceptible to acute air pollution. • Our findings provide evidence for optimizing greenness in an urban environment. [ABSTRACT FROM AUTHOR]

Background: Ambient PM1 (particulate matter with aerodynamic diameter ≤1 μm) is an important contribution of PM2.5 mass. However, little is known worldwide regarding the PM1-associated health effects due to a wide lack of ground-based PM1 measurements from air monitoring stations.Methods: We collected daily records of hospital admission for respiratory diseases and station-based measurements of air pollution and weather conditions in Shenzhen, China, 2015-2016. Time-stratified case-crossover design and conditional logistic regression models were adopted to estimate hospitalization risks associated with short-term exposures to PM1 and PM2.5.Results: PM1 and PM2.5 showed significant adverse effects on respiratory disease hospitalizations, while no evident associations with PM1-2.5 were identified. Admission risks for total respiratory diseases were 1.09 (95% confidence interval: 1.04 to 1.14) and 1.06 (1.02 to 1.10), corresponding to per 10 μg/m3 rise in exposure to PM1 and PM2.5 at lag 0-2 days, respectively. Both PM1 and PM2.5 were strongly associated with increased admission for pneumonia and chronic obstructive pulmonary diseases, but exhibited no effects on asthma and upper respiratory tract infection. Largely comparable risk estimates were observed between male and female patients. Groups aged 0-14 years and 45-74 years were significantly affected by PM1- and PM2.5-associated risks. PM-hospitalization associations exhibited a clear seasonal pattern, with significantly larger risks in cold season than those in warm season among some subgroups.Conclusions: Our study suggested that PM1 rather than PM1-2.5 contributed to PM2.5-induced risks of hospitalization for respiratory diseases and effects of PM1 and PM2.5 mainly occurred in cold season. [ABSTRACT FROM AUTHOR]

Ambient air pollution and cigarette smoking are two significant risk factors for mortality; however, less is known about their interaction. We aimed to examine effect modification of cigarette smoking on the association between short-term exposure to air pollution and mortality in the Chinese Elderly Health Service Cohort in Hong Kong. We included 16,290 Chinese elders aged 65 years or older who died between 1 July 1998 and 31 December 2011. Smoking history was collected through face-to-face interviews by registered nurses or doctors using a standardized structured questionnaire when they were recruited into the cohort. We used a time-stratified case-crossover approach to estimate the percent excess risk (ER%) of all-natural mortality per 10 μg/m3 increase in fine particulate matter (PM 2.5), respirable particulate matter (PM 10), and nitrogen dioxide (NO 2) among current-, ex-, and never-smokers, and to estimate the additional percent excess risk (ΔER%) for current- and ex-smokers relative to never-smokers. We performed secondary analysis to assess whether the estimated additional risks varied by personal characteristics. There were greater ERs % associated with air pollutants among current- and ex-smokers relative to never-smokers. We found ΔER% per 10 μg/m3 increase in air pollutants was statistically significant for PM 2.5 among ex-smokers [2.63% (95% CI: 0.39%, 4.88%) at 1 day prior to death (lag 1)], and PM 10 among current-smokers [2.21% (95% CI: 0.08%, 4.33%) at lag 1 ] and ex-smokers [1.96% (95% CI: 0.26%, 3.65%) at lag 1 ]. The increased risks associated with cigarette smoking were more pronounced among males, overweight or obese elders, elders with three or more comorbidities, or elders received primary or lower education. Ever-smokers were more susceptible to excess mortality risk associated with daily air pollution, especially for males, overweight or obese elders, and those with poor health conditions or received lower educational attainment. Tobacco control can reduce the health burdens attributable to air pollution. • Ever-smokers are more susceptible to short-term air pollution exposure. • The higher risks due to smoking are stronger among males, overweight elders, or elders with worse health. • Tobacco control can reduce health burdens attributable to air pollution. [ABSTRACT FROM AUTHOR]

Short-term exposure to ambient air pollution (AAP) has been widely linked to asthma morbidity such as outpatient and emergency visits and hospitalization. Up to date, however, the acute effects of AAP exposure on asthma mortality remained largely unknown possibly due to the rare occurrence of asthma deaths. This study aimed to investigate whether the death risks from asthma are triggered by short-term AAP exposures in a Chinese urban population who suffered poor air quality. 1385 asthma death cases were identified from the total 61.3 thousand death records in two urban districts in Wuhan, central China, 2003–2013. We performed a time-stratified case-crossover design and conditional logistic regression models were applied to assess short-term associations of air pollutants (particulate matter with aerodynamic diameter ≤10 μm [PM 10 ], sulfur dioxide [SO 2 ], and nitrogen dioxide [NO 2 ]) along different exposure days with asthma mortality. A total of 1385 case days and 4668 control days were investigated during the study period. Daily mean concentrations of PM 10 , SO 2 , and NO 2 were 116.6 μg/m3, 53.4 μg/m3, and 60.7 μg/m3, respectively. A 10 μg/m3 rise in exposure to SO 2 and NO 2 at 2 days prior to death (lag 2 days), was associated with increased asthma death risks of 2.9% (odds ratio [OR] = 1.029, 95% confidence interval [CI]: 1.006, 1.053) and 4.3% (OR = 1.043, 95% CI: 1.012, 1.076), respectively. No evident PM 10 -asthma associations were identified in all subpopulations except for those aged 85+ years (OR = 1.022, 95% CI: 1.001 to 1.044). In our stratified analyses, significant effects of SO 2 and NO 2 were only observed in female, the older elderly, 7+ years-educated and unmarried persons, as well as those died outside the hospital and in cold season. We observed some evidence for effect modification by age, with p-values of 0.032 for PM 10 and 0.051 for SO 2 , suggesting higher vulnerability to air pollution among the older asthma cases. This study provided suggestive evidence for the short-term association between air pollution exposure and asthma death in highly polluted urban areas. Several days' high-level exposures to air pollutants, particularly SO 2 and NO 2 , may elevate risks of asthma death. Our findings highlighted the potential health benefits from intervention and preventive actions targeted to reducing AAP exposure among asthma patients. • Short-term effects of ambient air pollution (AAP) on asthma mortality were assessed. • Several days' high-level exposures to SO 2 and NO 2 elevated risks of asthma death. • AAP-asthma death associations varied by subpopulations and season. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the association between psychological factors and pain exacerbations in people with hip OA., Methods: Eligible participants with symptomatic hip OA were instructed to complete online questionnaires every 10 days over a 90-day follow-up period. In addition, they were required to complete the questionnaire whenever they perceived they were experiencing a hip pain exacerbation. Hip pain exacerbation was defined as an increase of 2 points in pain intensity compared with baseline on an 11-point numeric rating scale (0-10). The Depression, Anxiety and Stress Scale-21 Items, Positive and Negative Affect Schedule, Pain Catastrophizing Scale and Pain Self-Efficacy Questionnaire were used to evaluate psychological factors. The associations of these with risk of hip pain exacerbation were examined by conditional logistic regression., Results: Of 252 participants recruited, 131 (52.0%) contributed both case and control period data and were included in the analysis. A significant association was found between Pain Catastrophizing Scale overall score (1 point increase) with hip pain exacerbations (odds ratio: 1.07, 95% CI: 1.04, 1.11). An increase of a minimal important change (5.5 points) of Pain Self-Efficacy Questionnaire score was associated with a lower odds of pain exacerbations (odds ratio: 0.74, 95% CI: 0.65, 0.85). No significant associations were found between Depression, Anxiety and Stress Scale-21 Items or Positive and Negative Affect Schedule scores with hip pain exacerbations., Conclusion: Both pain catastrophizing and pain self-efficacy beliefs were associated with pain exacerbations in people with hip OA, but other psychological factors including depression, anxiety and stress or positive and negative affects, were not associated with pain exacerbations., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: The case-crossover design is suited to medication safety studies but is vulnerable to exposure misclassification. Using the example of tricyclic antidepressants and the risk of hip fracture, we present a data visualisation tool for observing exposure misclassification in case-crossover studies., Methods: A case-crossover study was conducted using Australian Government Department of Veterans' Affairs claims data. Beneficiaries aged over 65 years who were hospitalised for hip fracture between 2009 and 2012 were included. The case window was defined as 1-50 days pre fracture. Control window one and control window two were defined as 101-150 and 151-200 days pre fracture, respectively. Patients were stratified by whether exposure status changed when control window two was specified instead of control window one. To visualise potential misclassification, each subject's tricyclic antidepressant dispensings were plotted over the 200 days pre fracture., Results: The study population comprised 8828 patients with a median age of 88 years. Of these subjects, 348 contributed data to the analyses with either control window. The data visualisation suggested that 14% of subjects were potentially misclassified with control window one while 45% were misclassified with control window two. The odds ratio for the association between tricyclic antidepressants and hip fracture was 1.18 (95% confidence interval = 0.91-1.52) using control window one, whereas risk was significantly increased (odds ratio = 1.43, 95% confidence interval = 1.11-1.83) using control window two., Conclusions: Exposure misclassification was less likely to be present with control window one than with an earlier control window, control window two. When specifying different control windows in a case-crossover study, data visualisation can help to assess the extent to which exposure misclassification may contribute to variable results.

Background: HIV disproportionately affects men who have sex with men (MSM) in China. The HIV epidemic is largely driven by unprotected anal sex (ie, sex not protected by condoms or HIV pre-exposure prophylaxis [PrEP]). The possible association between unprotected anal sex and the use of geospatial networking apps has been the subject of scientific debate., Objective: This study assessed whether users of a gay geospatial networking app in China were more likely to use condoms when they met their partners online versus offline. A case-crossover analysis, with each person serving as his own control, was employed to address the potential bias that men looking for sex partners through an online dating medium might have inherently different (and riskier) patterns of sexual behavior than men who do not use online dating media., Methods: A cross-sectional survey was administered in 2018 to adult male users of Blued-a gay geospatial networking app-in Beijing, Tianjin, Sichuan, and Yunnan, China. A case-crossover analysis was conducted among 1311 MSM not taking PrEP who reported engaging in both unprotected and protected anal sex in the previous 6 months. Multivariable conditional logistic regression was used to quantify the association between where the partnership was initiated (offline or online) and the act of unprotected anal sex, controlling for other interval-level covariates. Four sensitivity analyses were conducted to assess other potential sources of bias., Results: We identified 1311 matched instances where a person reported having both an unprotected anal sex act and a protected anal sex act in the previous 6 months. Of the most recent unprotected anal sex acts, 22.3% (292/1311), were initiated offline. Of the most recent protected anal sex acts, 16.3% (214/1311), were initiated offline. In multivariable analyses, initiating a partnership offline was positively associated with unprotected anal sex (odds ratio 2.66, 95% CI 1.84 to 3.85, P<.001) compared with initiating a partnership online. These results were robust to each of the different sensitivity analyses we conducted., Conclusions: Among Blued users in 4 Chinese cities, men were less likely to have unprotected anal sex in partnerships that they initiated online compared with those that they initiated offline. The relationship was strong, with over 2.5 times the likelihood of engaging in unprotected anal sex in partnerships initiated offline compared with those initiated online. These findings suggest that geospatial networking apps are a proxy for, and not a cause of, high-risk behaviors for HIV infection; these platforms should be viewed as a useful venue to identify individuals at risk for HIV transmission to allow for targeted service provision., (©Justin Knox, Yi-No Chen, Qinying He, Guowu Liu, Jeb Jones, Xiaodong Wang, Patrick Sullivan, Aaron Siegler. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 15.01.2021.)

Environmental epidemiology is a science that applies traditional epidemiology methods and combines the characteristics of the relationship between environment and population health, and studies the relationship between external environmental factors and population health from a macro perspective. The following methods are usually used. (1) Descriptive research: including ecological research and current situation research. (2) Analytical research: including case-control research and group research. (3) Experimental epidemiological research. In this section, according to the short-term and long-term effects of studying environmental risk factors, it is divided into two parts. Short-term effect methods include time series study, case-crossover study, and panel study. Long-term effect methods include cross-sectional study, case-control study, and cohort study.

Objective: Thirty-four geothermal power plants for the production of electricity are currently active in the geothermal areas in Tuscany. The present study aimed to investigate the association between short-term exposure to hydrogen sulfide (H 2 S) and acute health outcomes., Methods: This study used individual data on non-accidental, cardiovascular and respiratory mortality, urgent hospital admissions (HA) and emergency department (ED) visits for cardiorespiratory diseases occurring from 2000 to 2017. All cases were georeferenced and matched to daily H 2 S data, derived from 18 monitoring sites. A case-crossover design following the matched pair interval approach was applied and conditional logistic regression models were fitted to estimate odds ratios and their 90% confidence intervals, adjusting for a set of time-dependent variables, such as influenza epidemics, holidays and temperature., Results: A total of 8054 deaths, 30,527 HA and 15,263 ED visits occurred. Mortality for non-accidental (OR = 1.11, 90% CI 1.02-1.22) and cardiovascular causes (OR = 1.22, 90% CI 1.03-1.44) were associated with an increase of 10 µg/m 3 of H 2 S daily levels only among men. Hospital admissions for respiratory diseases were positively associated with H 2 S exposure: OR = 1.11 (90% CI 1.00-1.22) among women. No associations were observed in ED visits analyses., Conclusions: In this case-crossover study in the Tuscan geothermal areas, short-term exposure to H 2 S was weakly associated with some mortality and morbidity outcomes. Our findings did not show a clear pattern as the results were not homogeneous between mortality and morbidity data or between men and women.

With a case-crossover design, a case's exposure during a risk period is compared to the case's exposures at referent periods. The selection of referents for this self-controlled design is determined by the referent selection strategy (RSS). Previous research mainly focused on systematic bias associated with the RSS. We additionally focused on how RSS determines the number of referents per risk, sensitivity to overdispersion and time-varying confounding.We illustrated the consequences of different RSS using a simulation study informed by data on meteorological variables and Legionnaires' disease. By randomising the events and exposure time series, we explored statistical power associated with time-stratified and fixed bidirectional RSS and their susceptibility to systematic bias and confounding bias. In addition, we investigated how a high number of events on the same date (e.g. outbreaks) affected coefficient estimation. As illustrated by our work, referent selection alone can be insufficient to control for a time-varying confounding bias. In contrast to systematic bias, confounding bias can be hard to detect. We studied potential solutions: varying the model parameters and link-function, outlier-removal and aggregating the input-data over smaller areas. Our simulation study offers a framework for researchers looking to detect and to avoid bias in case-crossover studies.

The number of reported cases with Legionnaires' disease (LD) is increasing in Belgium. Previous studies have investigated the associations between LD incidence and meteorological factors, but the Belgian data remained unexplored. We investigated data collected between 2011 and 2019. Daily exposure data on temperature, relative humidity, precipitation and wind speed was obtained from the Royal Meteorological Institute for 29 weather stations. Case data were collected from the national reference centre and through mandatory notification. Daily case and exposure data were aggregated by province. We conducted a time-stratified case-crossover study. The 'at risk' period was defined as 10 to 2 days prior to disease onset. The corresponding days in the other study years were selected as referents. We fitted separate conditional Poisson models for each day in the 'at risk' period and a distributed lag non-linear model (DLNM) which fitted all data in one model. LD incidence showed a yearly peak in August and September. A total of 614 cases were included. Given seasonality, a sequence of precipitation, followed by high relative humidity and low wind speed showed a statistically significant association with the number of cases 6 to 4 days later. We discussed the advantages of DLNM in this context.

Background: Ambient PM 1 (particulate matter with aerodynamic diameter ≤1 μm) is an important contribution of PM 2.5 mass. However, little is known worldwide regarding the PM 1 -associated health effects due to a wide lack of ground-based PM 1 measurements from air monitoring stations., Methods: We collected daily records of hospital admission for respiratory diseases and station-based measurements of air pollution and weather conditions in Shenzhen, China, 2015-2016. Time-stratified case-crossover design and conditional logistic regression models were adopted to estimate hospitalization risks associated with short-term exposures to PM 1 and PM 2.5 ., Results: PM 1 and PM 2.5 showed significant adverse effects on respiratory disease hospitalizations, while no evident associations with PM 1-2.5 were identified. Admission risks for total respiratory diseases were 1.09 (95% confidence interval: 1.04 to 1.14) and 1.06 (1.02 to 1.10), corresponding to per 10 μg/m 3 rise in exposure to PM 1 and PM 2.5 at lag 0-2 days, respectively. Both PM 1 and PM 2.5 were strongly associated with increased admission for pneumonia and chronic obstructive pulmonary diseases, but exhibited no effects on asthma and upper respiratory tract infection. Largely comparable risk estimates were observed between male and female patients. Groups aged 0-14 years and 45-74 years were significantly affected by PM 1 - and PM 2.5 -associated risks. PM-hospitalization associations exhibited a clear seasonal pattern, with significantly larger risks in cold season than those in warm season among some subgroups., Conclusions: Our study suggested that PM 1 rather than PM 1-2.5 contributed to PM 2.5 -induced risks of hospitalization for respiratory diseases and effects of PM 1 and PM 2.5 mainly occurred in cold season., Competing Interests: Declaration of competing interest The authors declare they have no competing financial interests., (Copyright © 2019 Elsevier GmbH. All rights reserved.)