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Despite mounting evidence linking asthma to air pollution, it remains unclear which specific pollutant(s) exposure during critical time window(s) plays a pivotal role in the development of asthma. The objective of this study is to investigate the effects of intrauterine and postnatal air pollution exposure on children's asthma. From 2019 to 2020, a retrospective cohort study was conducted in Changsha, China. The inverse distance weighted (IDW) method was used to estimate each child's personal exposure to outdoor air pollutants at their home address. Associations between personal air pollution exposure and asthma were comprehensively examined. The occurrence of children's asthma was found to be linked to exposure to PM 2.5 and NO 2 during both the intrauterine and current periods, with significant ORs (95% CI) of 1.44 (1.08–1.93) and 1.29 (1.00–1.68) for IQR increase in intrauterine exposure particularly during the 2nd trimester, and 1.26 (1.01–1.57) and 1.26 (1.04–1.51) for exposure in previous year. Post-natal PM 10 exposure was linked to asthma, with an OR (95% CI) of 1.28 (1.01–1.62). Higher risks of asthma were associated with intrauterine exposure to PM 2.5 and postnatal exposure to PM 10. The critical time windows for PM 2.5 , PM 2.5-10 , and PM 10 exposure were identified as the entire pregnancy, the second trimester, and the entire postnatal period, respectively. Cumulative exposure to PM 2.5 and NO 2 during gestational weeks had a notable impact on asthma. Additionally, exposure to traffic-related air pollution (TRAP) at all timing stages, as well as PM 2.5-10 and SO 2 at night, increased the risk of asthma. Certain subgroups were more vulnerable to asthma risk due to air pollution. Children's asthma was predominantly influenced by exposure to particulate matters and TRAP during both the intrauterine and postnatal periods. [Display omitted] • Traffic-related air pollution (TRAP) exposure was related with childhood asthma. • Pregnancy, 2nd trimester, and postnatal period were critical widows for PM exposure. • Daytime and nighttime TRAP exposure played an important role in the risk of asthma. • There were cumulative effects of PM 2.5 and NO 2 over gestation in relation to asthma. • Our study supports and develops the "fetal origin of childhood asthma" hypothesis. [ABSTRACT FROM AUTHOR]

Childhood pneumonia remains a major public health concern worldwide, but the critical meteorological factors that contribute to it are unknown. To investigate the relationship between childhood pneumonia and prenatal and postnatal exposure to meteorological factors to identify the critical factors and vulnerable timing windows. We conducted a retrospective cohort study of 8689 preschoolers in China. We gathered information on personal factors, health status, and indoor environment through questionnaires. We considered meteorological factors including temperature (mean, maximum, minimum), diurnal temperature variation (DTV), relative humidity, wind speed, rainfall, pressure and sunshine during early life. Using multiple logistic regression models, we investigated the links between childhood pneumonia and early life exposure to meteorological factors. Exposure to mean, maximum, and minimum temperatures was associated with childhood pneumonia in the first month and first trimester, with ORs (95% CI) of 1.32 (1.07–1.62), 1.26 (1.04–1.52) and 1.33 (1.08–1.64) in the first month, and 1.42 (1.12–1.81), 1.36 (1.08–1.71) and 1.47 (1.15–1.88) in the first trimester for per IQR increase in each meteorological factor exposure. Wind speed, rainfall, and sunshine exhibited significant associations with pneumonia during the first, second, and third trimesters, respectively. Exposure to various temperatures, DTV, relative humidity, rainfall, air pressure, and sunshine were linked to childhood pneumonia in the postnatal period, particularly in the previous year. The sensitivity analysis revealed that boys are more vulnerable to meteorological factors. Keeping dogs or plants may offer protection against the pneumonia risk of prenatal and postnatal meteorological exposure. Exposure to meteorological factors during both the prenatal and postnatal periods, especially in early pregnancy, was found to elevate the risk of childhood pneumonia. [Display omitted] • Effect of climatic factors on childhood pneumonia in different windows is unclear. • Pneumonia in children was associated with prenatal exposure to ambient temperature. • Early pregnancy was identified as a critical time window for climatic exposure. • Postnatal exposure to climatic factors had the highest risk of childhood pneumonia. • Our study support "Fetal origin of pneumonia" hypothesis by meteorological factors. [ABSTRACT FROM AUTHOR]

Abstract Background Mounting evidence have linked high temperature with increased incidence of preterm birth (PTB), but which time period(s) of increase in temperature within a day and a year during pregnancy play an important role in PTB is not clarified. Objective This study aims to determine the critical time period(s) of heat exposure on the development of PTB by exploring the risk of PTB for temperature increase during 24 h of a whole day and each of four seasons during pregnancy. Methods A cohort study was performed with 3509 preschool children in Changsha, China, which evaluated the prevalence of PTB using a questionnaire filled out by the children's parents. The authors estimated the temperature at which each mother was exposed to outdoor air temperature during three trimesters and for 24 h in different seasons of pregnancy. The logistic regression models in regard to odds ratio (OR) and 95% confidence interval (CI) was applied to study associations of PTB with an increase in temperature during different time windows. Results Prevalence of PTB (4.1%) was associated with outdoor temperature with adjusted ORs (95% CI) = 1.34 (1.11–1.62) for increase of 1 °C in temperature exposure during pregnancy, and this association was significantly higher in spring and summer than autumn and winter. Specifically, high temperature during summer night posed the highest risk of PTB, with peaks during 03:00–04:00 a.m. We further found that PTB was associated with exposure to temperature and extreme heat day during the 2nd trimester, with ORs = 1.03 (1.00–1.06) and 1.01 (1.00–1.02) respectively. Foetus with male sex and older mothers were more sensitive to the impact of heat exposure during pregnancy on PTB, with higher risk observed during night time. Conclusion Our study indicates that heat exposure was related to an elevated risk of PTB, with higher risk of PTB for nocturnal exposure and warm seasons. Our findings have implications for the adverse effect of elevated temperature in the future as global warming continues. Highlights • Preterm birth (PTB) was associated with increase in ambient temperature. • We identified 2nd trimester as a critical timing window for the PTB risk of heat exposure. • Temperature increase in warm season posed a significantly higher risk compared to cold season. • PTB risk due to increase in temperature was higher during night time than daytime. [ABSTRACT FROM AUTHOR]

Despite mounting evidence linking allergic rhinitis (AR) to air pollution, it remains unclear which major air pollutant(s) and critical window(s) of exposure play important roles in children's AR. To examine the effects of intrauterine and early postnatal exposure to outdoor air pollution on children with doctor-diagnosed allergic rhinitis (DDAR). A retrospective cohort study involving 8689 kindergarten children was conducted in Changsha, China, from 2019 to 2020. A questionnaire survey was conducted to collect information on the health status of children and their family members, as well as their living habits and home environment. Personal exposure to daily outdoor air pollutants (PM 2.5 , PM 2.5-10 , PM 10 , SO 2 , NO 2 , and CO) was estimated during 40 gestational weeks, three trimesters, the entire pregnancy, and the first year after birth. Multiple logistic regression models were used to assess the associations between air pollution and children's DDAR. Children's DDAR was associated with intrauterine CO exposure, with adjusted ORs (95% CI) of 1.18 (1.03–1.34) for each IQR increase in CO exposure. The second and third trimesters were critical windows for PM 2.5 and CO exposure in relation to DDAR. Furthermore, early postnatal exposure to PM 2.5-10 and PM 10 in first year of life was associated with DDAR development, with adjusted ORs (95% CI) of 1.11 (1.01–1.22) and 1.27 (1.09, 1.47). The entire pregnancy and the first year of life were critical windows for CO and PM 10 exposure. Some children were predisposed to DDAR risk due to exposure to traffic-related air pollution (TRAP). Our findings support the hypothesis of "fetal origin of allergic rhinitis" by demonstrating that intrauterine and early postnatal exposure to air pollution plays an important role in children's DDAR. [Display omitted] • Allergic rhinitis (AR) was affected by traffic-related air pollution (TRAP). • Prenatal exposure to CO and PM 2.5 enhanced the risk of childhood AR. • Early postnatal exposure to PM 10 and NO 2 was associated with childhood AR. • Some sub-groups were more susceptible to AR risk of air pollution exposure. • Our study supports and develops the hypothesis of "fetal origin of allergic rhinitis". [ABSTRACT FROM AUTHOR]

Despite mounting evidence linked pneumonia with air pollution, it is unclear what main pollutant(s) exposure in which critical window(s) play a key role in pneumonia. To examine effects of intrauterine and post-natal exposure to air pollution on children's doctor-diagnosed pneumonia (DDP). A combination of cross-sectional and retrospective cohort study was conducted at Changsha, China during 2019–2020. Personal exposure to outdoor air pollutants at each child's home address was estimated using inverse distance weighted (IDW) method based on data from 10 air quality monitoring stations. Associations between personal air pollution exposure and DDP were evaluated. Children's DDP was associated with intrauterine and post-natal exposure to PM 2.5 , PM 2.5–10 , and PM 10 , adjusted ORs (95% CI) of 1.17 (1.04–1.30), 1.09 (1.01–1.17), and 1.07 (1.00–1.14) for IQR increase in intrauterine exposure and 1.12 (1.02–1.22), 1.13 (1.06–1.21), and 1.28 (1.16–1.41) for post-natal exposure. Intrauterine PM 2.5 exposure and post-natal PM 10 exposure were associated with a higher risk of pneumonia. We identified the 2nd trimester, 3rd trimester, and first year as critical windows respectively for PM 2.5 , PM 2.5–10 , and PM 10 exposure. Daytime exposure to traffic-related air pollution especially during early life increased DDP. Intrauterine and post-natal exposure to particulate matters played a dominant role in children's DDP. [Display omitted] • Childhood pneumonia was dominantly affected by particulate matters (PMs) exposure. • Intrauterine exposure to PM 2.5 especially in 2nd trimester enhanced pneumonia risk. • Postnatal exposure PM 10 particularly in first year elevated pneumonia risk. • Daytime was identified as key time for traffic pollution in relation to pneumonia. • Our study supports and develops the hypothesis of 'fetal origin of infection. [ABSTRACT FROM AUTHOR]

Despite numerous studies demonstrating a link between asthma and meteorological parameters, the role of maternal exposure in pregnancy on childhood asthma remains unknown. To investigate the association of meteorological factors during pregnancy with childhood asthma and identify key exposure windows. In central China's Changsha city, we carried out a retrospective cohort study involving 8,689 preschoolers. We used questionnaires to collect information about childhood health, personal factors, socioeconomic status (SES), and indoor environment. We considered meteorological parameters including temperature (mean, maximum, minimum), diurnal temperature variation (DTV), relative humidity, wind speed (mean, extreme), rainfall, pressure, and sunshine during early life. We investigated the links between childhood asthma and meteorological factors using logistic regression models. Doctor-diagnosed asthma (D-DA) in preschoolers was associated with exposure to increased temperatures (mean, maximum, and minimum) by per IQR increment in the first month with ORs (95% CI) of 2.03 (1.21–3.40), 1.86 (1.15–3.00) and 2.08 (1.23–3.50) as well as in the first trimester with ORs of 2.40 (1.36–4.24), 2.20 (1.26–3.83) and 2.54 (1.43–4.53), respectively. D-DA was inversely related to wind speed in the first month and first two trimesters. Compared to an increased risk of D-DA when exposed to pressure in the third trimester, exposure to DTV during pregnancy, particularly in the third trimester, significantly decreased the risk. Some preschoolers with certain personal factors and high SES were more vulnerable to pre-natal meteorological exposure. Prenatal exposure to meteorological factors, especially high temperatures and low wind speeds in early pregnancy, contributes to childhood asthma. [Display omitted] • The impact of meteorological factors in pregnancy on childhood asthma is unclear. • Asthma was linked to higher temperatures and lower wind speed in pregnancy. • Early pregnancy was identified as a critical window for climatic susceptibility. • Personal and socioeconomic factors modified asthma risk of climate exposure. • Our study supports "Fetal origins of asthma" hypothesis by meteorological factors. [ABSTRACT FROM AUTHOR]

Background Otitis media (OM) is a common infection in early childhood with repeated attacks that lead to long-term complications and sequelae, but its etiology still remains unclear. Objective To examine the association between early life exposure to air pollution and childhood OM, with the purpose of identifying critical windows of exposure and key components of air pollution in the development of OM. Methods We conducted a prospective cohort study of 1617 children aged 3–4 years in Changsha, China (2011–2012). The prevalence of OM was assessed by a questionnaire administered by the parents. Individual exposures to nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ) and particulate matter with an aerodynamic diameter ≤ 10 μm (PM 10 ) during prenatal, postnatal, and current windows were estimated using the measured concentrations at monitoring stations. We used logistic regression model to examine the OM risk in terms of odds ratio (OR) and 95% confidence interval (CI) for exposure to different air pollutants during different timing windows, adjusting for covariates, multi-pollutants, and multi-windows. Results Life-time prevalence of doctor-diagnosed OM in preschool children in Changsha was 7.3%. Childhood OM was associated only with prenatal exposure to the industrial air pollution with adjusted OR (95% CI) = 1.44 (1.09–1.88) for a 27 μg/m3 increase in SO 2 , particularly during the first trimester of pregnancy. We further found that prenatal SO 2 exposure was not associated with the repeated attacks but was associated with the onset of OM, adjusted OR (95% CI) = 1.47 (1.10–1.96). The association between prenatal SO 2 exposure and early childhood OM was robust after adjusting for other pollutants and windows. Sensitivity analysis indicated that the association was stronger in females, children with parental atopy, and children living in houses with cockroaches, new redecoration, and condensation on window pane during winter. Conclusion We provide new evidence that prenatal exposure to industrial air pollution is associated with early childhood OM in China and may contribute to the onset of childhood OM. Our findings are helpful in developing more effective preventative strategies for childhood OM. [ABSTRACT FROM AUTHOR]

Background Childhood pneumonia is one of the leading single causes of mortality and morbidity in children worldwide, but its etiology still remains unclear. Objective We investigate the association between childhood pneumonia and exposure to diurnal temperature variation (DTV) in different timing windows. Methods We conducted a prospective cohort study of 2,598 children aged 3–6 years in Changsha, China. The lifetime prevalence of pneumonia was assessed by a questionnaire administered by the parents. Individual exposure to DTV during both prenatal and postnatal periods was estimated. Logic regression models was used to examine the association between childhood pneumonia and DTV exposure in terms of odds ratios (OR) and 95% confidence interval (CI). Results Lifetime prevalence of childhood pneumonia in preschool children in Changsha was high up to 38.6%. We found that childhood pneumonia was significantly associated with prenatal DTV exposure, with adjusted OR (95%CI) =1.19 (1.02–1.38), particularly during the second trimester. However, childhood pneumonia not associated with postnatal DTV exposure. Sensitivity analysis indicated that boys are more susceptible to the pneumonia risk of diurnal temperature variation than girls. We further observed that the prevalence of childhood pneumonia was decreased in recent years as DTV shrinked. Conclusions Early childhood pneumonia was associated with prenatal exposure to the diurnal temperature variation (DTV) during pregnancy, particularly in the second trimester, which suggests fetal origin of childhood pneumonia. [ABSTRACT FROM AUTHOR]

Background Evidence linking prenatal exposure to outdoor air pollution with eczema in early childhood is scare, and the role of components of air pollution and exposure timing remains unclear. Objectives We investigated the association between exposure to air pollution during preconceptional and perinatal period and the risk of eczema in preschool children. Methods We conducted a prospective cohort study of 2598 children aged 3–6 years in Changsha, China. The prevalence of eczema was assessed by a standardized health questionnaire administered by the parents. Individual exposures to nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ) and particulate matter with an aerodynamic diameter ≤ 10 μm (PM 10 ) during the 4th-6th and 1st-3rd month before pregnancy, entire pregnancy, and three trimesters were estimated by an inverse distance weighted (IDW) method based on concentrations measured at monitoring stations. Association between childhood eczema and exposure to air pollution was examined by logistic regression models in terms of odds ratio (OR) and 95% confidence interval (CI) for an interquartile range (IQR) increase in exposure. Results Life-time prevalence of eczema in preschool children in Changsha was 28.6%. Childhood eczema was associated with traffic-related air pollutant NO 2 during 3 months before pregnancy and entire pregnancy with adjusted ORs = 1.19 (95% CI: 1.04–1.37) and 1.21 (95% CI: 1.03–1.42) respectively. The highest risk of eczema was observed for the 1st trimester exposure to NO 2 [OR = 1.26 (95% CI: 1.09–1.46)]. However, no association was detected for SO 2 and PM 10 exposure during any window. High-level exposure to NO 2 during the whole time period significantly increased the effect of NO 2 in all windows on eczema risk as compared with low-level exposure. Sensitivity analysis indicated that the association between both preconceptional and perinatal exposure to NO 2 and childhood eczema was consistent and robust, and this association was modified by some personal, parental hereditary and indoor environmental factors. Conclusion Our findings support the hypothesis that early childhood eczema is associated with exposure to traffic-related air pollutant during both preconceptional and perinatal period, especially at a high level of exposure. [ABSTRACT FROM AUTHOR]

Food allergy increased in the recent years causing heavy disease burden worldwide, yet the unique factors for the second-wave allergy epidemic since a rise of allergic diseases are unclear. To examine the impact of introduction timing of complementary foods on childhood food allergy and whether ambient air pollution modify this association. A retrospective cohort study of 2,598 preschoolers was conducted at 36 kindergartens at Changsha of China during 2011–2012. A standard questionnaire was developed to survey each preschooler's introduction timing of complementary foods, food allergy, and home environments. Each subject's exposure to ambient air pollutants including PM 10 , SO 2 , and NO 2 was estimated for pregnancy and postnatal period. Association between food allergy and introduction timing of complementary foods as well as its modification by ambient pollution were evaluated by multiple logistic regression model. Childhood total food allergy (14.6%) was significantly positively associated with early introduction to fruit or vegetable before 3 months with OR = 1.97 (1.25–3.11), especially for egg and milk allergies. Food allergy was also significantly associated with NO 2 exposure in pregnancy especially during the 1st trimester with ORs (95% CI) = 1.24 (1.00–1.54) and 1.27 (1.03–1.58) and postnatal period with OR of 1.30 (1.01–1.66) respectively for per IQR increase in their exposure. We observed that living near traffic-main road and other areas significantly increased food allergy risk of early introduction of fruit and vegetable. We further detected that early introduction of milk powder or porridge significantly decreased the risk of food allergy at the condition of light outdoor air pollution exposure during postnatal period. Sensitivity analysis showed that children living at urban area, male sex, younger age, and having breast-feeding were more susceptible to the effect of early introduction of fruit and vegetable on food allergy. Our study indicates that the role of introduction timing of complementary foods on food allergy could be adjusted by air pollution exposure level, which may partly explain the second-wave allergy epidemic and provide a potential preventive strategy. [Display omitted] • Childhood food allergy was associated with early introduction of fruit and vegetable before 3 months. • Food allergy was related to NO 2 exposure in pregnancy especially 1st trimester and postnatal stage. • Living near traffic area increased food allergy risk of early introduction of fruits and vegetables. • Low air pollution increased protective effect of early introduction of food allergens on food allergy. • Air pollution modified effect of solid food addition at different time on food allergy development. [ABSTRACT FROM AUTHOR]

Background Mounting evidence suggests that exposure to ambient air pollution is associated with the development of childhood allergic diseases, but the effect of prenatal exposure to air pollution on the risk of childhood asthma and allergy is unclear. Objectives We evaluated the association between maternal exposure to outdoor air pollution during different trimesters of pregnancy and incidence of asthma, allergic rhinitis, and eczema in 2598 preschool children aged 3–6 years in China. Methods Children's lifetime incidence of allergic diseases was obtained using questionnaire. Individual exposure to outdoor air pollutants during trimesters of pregnancy was estimated by an inverse distance weighted (IDW) method based on the measured concentrations at monitoring stations. We used multiple logistic regression method to estimate the odds ratio (OR) of asthma, allergic rhinitis, and eczema for per interquartile range (IQR) increase in the exposure to air pollutant in each trimester, which was adjusted for the effect of other air pollutants and its effect in other trimesters by a multi-pollutant/trimester model. Results Incidence of asthma (6.8%), allergic rhinitis (7.3%), and eczema (28.6%) in children was associated with maternal exposure to traffic-related pollutant NO 2 during entire pregnancy with OR (95% confidence interval [CI]) respectively 1.63 (0.99–2.70), 1.69 (1.03–2.77), and 1.37 (1.04–1.80). After adjustment for other pollutants and trimesters, we found the association was significant only in specific trimester: the first trimester for eczema (1.54, 1.14–2.09), the second trimester for asthma (1.72, 1.02–2.97), and the third trimester for allergic rhinitis (1.77, 1.09–2.89). Sensitivity analysis indicated that the trimester sensitive to the development of allergic diseases was stable. Conclusion Maternal exposure to traffic-related air pollutant NO 2 during pregnancy, especially in specific trimesters, is associated with an increased risk of developing asthma, rhinitis, and eczema in children. Our results support the hypothesis that childhood allergic diseases originate in fetal life and are triggered by traffic-related air pollution in sensitive trimesters. [ABSTRACT FROM AUTHOR]

Mounting studies have associated asthma with environmental and climatic factors, but their interaction during pregnancy on childhood asthma are unclear. This study aims to investigate the interaction of in utero air pollution and environmental temperature exposure on childhood asthma, to identify key timing windows for exposure. A retrospective cohort study with 2,598 pre-schoolers was conducted during 2011–2012 in Changsha, China. Maternal exposure to three critical ambient air pollutants (PM 10 , SO 2 and NO 2 , as proxies of industrial and vehicular air pollution) and temperature (T), was assessed for the 40 gestational weeks, three trimesters of gestation, and entire pregnancy by an inverse distance weighted (IDW) method. Logistic regression analysis was used to examine the association of childhood asthma with air pollution and temperature exposure. Our results showed that pre-schooler's asthma was significantly associated with SO 2 and NO 2 exposure in utero, ORs = 1.46 (95% CI: 1.12–1.89) and 1.67 (95% CI: 1.24–2.26) by inter quartile range (IQR) increase of their exposure respectively. Significant risk was observed for exposure of SO 2 and NO 2 particularly during the 1st and 2nd trimesters and their specific gestational weeks. Pre-schooler's asthma was related with high temperature exposure during 1st trimester, OR = 2.33 (95% CI: 1.11–4.90) by IQR increase of T exposure. Low T and high T respectively increased the asthma risk of NO 2 exposure in the 1st and 3rd trimester. Boys were more susceptible to the temperature-pollution interaction on asthma development. Our study indicates that low and high temperature respectively during early and late pregnancy significantly increased the impact of air pollution exposure in utero on pre-schooler's asthma. [Display omitted] • Childhood asthma was mainly associated with prenatal exposure to SO 2 and NO 2 in pregnancy. • Asthma was related with high temperature (T) and more summer days in the 1st trimester. • Low T in 1st trimester and high T in 3rd trimester increased asthma risk of NO 2 exposure. • Boys were more susceptible to the temperature-pollution interaction on asthma risk. • Our study supports the hypothesis of "fetal origin of allergy" via temperature-pollution interaction. [ABSTRACT FROM AUTHOR]

Background Early life is suggested to be a critical time in determining subsequent asthma development, but the extent to which the effect of early-life exposure to ambient air pollution on childhood asthma is unclear. Objectives We investigated doctor-diagnosed asthma in preschool children due to exposure to ambient air pollution in utero and during the first year of life. Methods In total 2490 children aged 3–6 years participated in a questionnaire study regarding doctor-diagnosed asthma between September 2011 and January 2012 in China. Children’s exposure to critical air pollutants, sulfur dioxide (SO 2 ) as proxy of industrial air pollution, nitrogen dioxide (NO 2 ) as proxy of traffic pollution, and particulate matter≤10 µm in diameter (PM 10 ) as a mixture, was estimated from the concentrations measured at the ambient air quality monitoring stations by using an inverse distance weighted (IDW) method. Logistic regression analysis was employed to determine the relationship between early-life exposure and childhood asthma in terms of odds ratio (OR) and 95% confidence interval (CI). Results Association between early-life exposure to air pollutants and childhood asthma was observed. SO 2 and NO 2 had significant associations with adjusted OR (95% CI) of 1.45 (1.02–2.07) and 1.74 (1.15–2.62) in utero and 1.62 (1.01–2.60) and 1.90 (1.20–3.00) during the first year for per 50 µg/m 3 and 15 µg/m 3 increase respectively. Exposure to the combined high level of SO 2 and NO 2 in China significantly elevated the asthmatic risk with adjusted OR (95% CI) of 1.76 (1.18–2.64) in utero and 1.85 (1.22–2.79) during the first year compared to the low level exposure. The associations were higher for males and the younger children aged 3–4 than females and the older children aged 5–6. Conclusions Early-life exposure to ambient air pollution is associated with childhood asthma during which the level and source of air pollution play important roles. The high level and nature of combined industrial and traffic air pollution in China may contribute to the recent rapid increase of childhood asthma. [ABSTRACT FROM AUTHOR]

Low birth weight (LBW), as a major concern in public health, is now increasing worldwide, but its main indoor environmental factors remain unclear. We examined whether LBW including term-LBW (T-LBW) and preterm-LBW (P-LBW) was associated with maternal exposure to indoor environmental factors, with a purpose to identify the key indoor environmental factor(s) contributing to LBW. A nationwide retrospective cohort study of 30,735 pre-schoolers in six Chinese cities was performed from 2010 to 2012. One questionnaire survey was conducted to collect information on the pre-schoolers' birth outcomes and their maternal exposure of indoor environmental factors including new furniture, house redecoration, cooking fuels, mould/damp stains, and mouldy odour during pregnancy. Maternal exposure of traffic-related air pollutant (NO 2), industrial pollutant (SO 2), and inhalable particulate matter (PM 10), as well as meteorological parameters, was estimated in pregnancy. Associations of LBW, T-LBW and P-LBW with indoor environmental factors were evaluated by two-level (city-child) logistic regression models with an odds ratio (OR) and 95% confidence interval (CI). We found that P-LBW (1.0%) and T-LBW (1.4%) prevalence were respectively associated with persistent mould/damp stains and mouldy odour exposure in utero, ORs = 1.81 (95% CI: 1.01–3.24) and 1.49 (95% CI: 1.01–2.21). Exposure to high temperature and PM 2.5 in pregnancy significantly enhanced the effect of persistent mould/damp stains and/or mouldy odour on P-LBW and LBW, ORs (95% CI) = 2.92 (1.40–6.07) and 1.78 (1.00–3.15) with significant interaction p values of 0.067 and 0.094 respectively. Sensitivity analysis suggested that raising cats and dogs significantly increased LBW risk of persistent mould/damp stains and mouldy odour exposure. Our findings indicate that long-term exposure to indoor mould/damp stains and mouldy odour in utero plays a key role in LBW, and this association can be significantly modified by some specific personal, indoor, and outdoor factors. [Display omitted] • Mould/damp stains exposure was significantly associated with term-low birth weight (LBW). • Maternal exposure to residential mouldy odour significantly increased the risk of preterm-LBW. • High temperature and PM 2.5 enhanced LBW risk of mould/damp stains and mouldy odour. • Families with pets were more susceptible to LBW risk of mould/damp stains and mouldy odour. • Our study has a new implication for the effective reduction and early prevention of LBW. [ABSTRACT FROM AUTHOR]

Small for gestational age (SGA) is a major public health problem that affects 32.4 million infants worldwide and its prevalence is increasing rapidly in new-borns. However, the key risk factors and their exposure time window on the development of SGA are unclear. We aim to investigate the association between exposure to outdoor air pollution and indoor environmental factors during which critical timing window and SGA, and to evaluate which specific personal factors modify this association. A retrospective cohort study of 3509 infants was conducted in Changsha, China during 2011–2012. A questionnaire survey was performed to obtain the formation on infant's birth outcomes and prenatal exposure of indoor environmental factors containing parental (maternal and/or paternal) smoking, new furniture, house redecoration, mold or dampness, window condensation, and keeping dogs in gestational age. Intrauterine exposure to industrial air pollutant (SO 2), traffic-related air pollutant (NO 2) and inhalable particulate matter (PM 10) was estimated during three trimesters and entire pregnancy. Associations between outdoor air pollutants and indoor environmental factors and SGA, term SGA (TSGA) and preterm SGA (PSGA) were assessed by multiple logistic regression model in terms of odds ratio (OR) and 95% confidence interval (CI). Prevalence of SGA (5.2%) and TSGA (4.9%) were significantly associated with intrauterine exposure to outdoor SO 2 during the entire gestational age with adjusted ORs (95% CI) of 1.08 (1.01–1.15) and 1.08 (1.00–1.15) for per 10 μg/m3 increase in SO 2 exposure after adjusting for the covariates, indoor environmental factors, and outdoor air temperature, and PSGA prevalence (0.3%) was significantly related with PM 10 exposure during whole pregnancy with odds = 2.21 (1.08–4.51). However, no association was observed for traffic-related air pollutant NO 2 exposure. Specifically, the association was more significant for SO 2 exposure during the 1st and/or 2nd trimester. We further found that TSGA and PSGA were associated with indoor exposure to parental smoking and new furniture, respectively, ORs (95% CI) = 1.46 (1.00–2.11) and 10.95 (1.46–81.95). We observed that the odds of SGA and TSGA attributed to SO 2 exposure in the first two trimesters was only significant among families with parental smoking and new furniture in gestation. Sensitivity analysis showed that infants with female sex and born in cold months were more susceptible to the effect of outdoor SO 2 exposure during the first two trimesters and entire gestational age on SGA and TSGA. On the other hand, infants born in the cold season and by a younger mother were more sensitive to the effect of indoor parental smoking in utero on SGA and TSGA. Maternal exposure to industry-related air pollution and indoor environmental risk factors during pregnancy, particularly during the first two trimesters, significantly increased SGA risk, and some specific personal factors could modify these associations. [Display omitted] • Industrial air pollution was associated with small for gestational age (SGA). • We identified the first two trimesters as critical windows for SGA development. • Parental smoking and new furniture in utero increased risk of term and preterm SGA. • Parental smoking amplifies the effect of outdoor industrial air pollution on SGA. • Personal factors could interact with air pollution in critical windows on SGA risk. [ABSTRACT FROM AUTHOR]

Low birth weight (LBW) remains a major public health problem worldwide, yet its crucial environmental risk factors are still unclear. To examine the association between LBW (term and preterm LBW) and prenatal exposure to ambient air pollution and home environmental factors as well as their combination, in order to identify critical time window for exposure and key outdoor and indoor factors in LBW development. A cohort study of 3509 preschool children was performed in Changsha, China during the period 2011–2012. A questionnaire was conducted to survey each child's birth outcome and each mother's exposure to home environmental factors including parental smoking, new furniture, redecoration, mold/damp stains, window pane condensation, and household pets during pregnancy. Maternal exposure to inhalable particulate matter (PM 10), industrial air pollutant (SO 2), and traffic air pollutant (NO 2) was estimated during different time windows of gestation, including conception month, three trimesters, birth month, and whole gestation. Associations of term and preterm LBW with ambient air pollutants and home environmental factors were assessed by multiple logistic regression models in terms of odds ratio (OR) with 95% confidence interval (CI). Term LBW (TLBW) was significantly associated with exposure to ambient PM 10 during pregnancy, with OR (95% CI) = 1.47 (1.00–2.14) for per IQR increase after adjustment for the covariates and home environmental factors. Specifically, we identified the significant association in early phase of pregnancy including conception month (1.90, 1.09–3.30) and the first trimester (1.72, 1.10–2.69). We further found that TLBW was significantly related with parental smoking at home, OR (95% CI) = 2.17 (1.09–4.33). However, no association was observed for preterm LBW (PLBW). The TLBW risk of ambient air pollution and home environmental factors was independent each other and hence the combined exposure to ambient PM 10 and indoor parental smoking caused the highest risk. Sensitivity analysis suggested that foetus with younger mothers were significantly more susceptible to risk of indoor parental smoking, while those with smaller house and cockroaches were more sensitive to risk of outdoor PM 10 exposure. Prenatal exposure to combined outdoor and indoor air pollution, particularly in critical window(s) during early pregnancy, significantly increases the risk of term LBW. • Air pollution was associated with term low birth weight (LBW) but not with preterm LBW. • We found term LBW was associated with prenatal exposure to ambient inhalable particle (PM 10). • Term LBW was also related with parental smoking at home during pregnancy. • Exposure to combined outdoor and indoor air pollution posed the highest risk of term LBW. • Early pregnancy was identified as the most critical time window for exposure susceptibility. [ABSTRACT FROM AUTHOR]

Although mounting evidence have linked traffic-related air pollution (TRAP) with increased risk of preterm birth (PTB), whether it can interact with indoor environmental factors remains unknown, and its window(s) susceptibility at the stage of gestation is unclear. To explore PTB risk for prenatal exposure to traffic-related air pollution and home environmental factors during pregnancy, so as to identify critical window(s) in the combined effect of traffic air pollution and main home environmental factor(s) on PTB development. A retrospective cohort study of 3,509 preschool children was performed in Changsha, China during 2011–2012. The PTB prevalence was reported by the parents based on a questionnaire. We estimated each mother's exposure to traffic-related air pollutant NO 2 in different windows of gestation, including conception month, three trimesters, birth month, and whole gestation. Maternal exposure to home environmental factors was considered by renovation (new furniture/redecoration) in pregnancy, and mold/damp stains and window condensation during perinatal period. Associations of PTB with both ambient NO 2 and home environmental factors, and their interactions on PTB were evaluated by logistic regression models using odds ratio (OR) with 95% confidence interval (CI). Traffic air pollutant NO 2 exposure in utero was significantly associated with PTB, with adjusted odds ratio (OR) (95% CI) of 1.41 (1.00–1.98) for an IQR increase in NO 2 exposure during whole pregnancy, particularly in the conception month and 1st trimester. We further found a positive relationship between perinatal exposure to mold/damp stains in the homes and PTB, OR (95% CI) = 1.73 (1.04–2.90). Especially, we detected a significant interaction between outdoor NO 2 and indoor mold/damp stains on PTB risk. Male and female foetus were respectively more susceptible to perinatal mold/dampness at home and outdoor NO 2 exposure in early gestation. Our finding indicates that both outdoor traffic air pollutant and indoor mold/dampness play key roles in PTB development, and their interaction effect in early pregnancy significantly increases PTB risk. Image 1 • PTB was significantly associated with traffic air pollutant NO 2 exposure during pregnancy. • The effect of NO 2 exposure in the conception month and 1st trimester was more important. • Indoor mold/damp stains in pregnancy was also related with an increased risk of PTB. • There is a significant interaction between outdoor NO 2 and indoor mold/damp stains on PTB. • Sensitive populations were more susceptible to the PTB risk of outdoor and indoor air pollution. [ABSTRACT FROM AUTHOR]

It is well known that exposure to thermal stress during pregnancy can lead to an increased incidence of premature births. However, there is little known regarding window(s) of susceptibility during the course of a pregnancy. We attempted to identify possible windows of susceptibility in a cohort study of 3604 children in Changsha with a hot-summer and cold winter climatic characteristics. We examined the association between PTB and ambient temperature during different timing windows of pregnancy: conception month, three trimesters, birth month and entire pregnancy. We found a U-shaped relation between the prevalence of PTB and mean ambient temperature during pregnancy. Both high and low temperatures were associated with PTB risk, adjusted OR (95% CI) respectively 2.57 (1.98–3.33) and 2.39 (1.93–2.95) for 0.5 °C increase in high temperature range (>18.2°C) and 0.5°C decrease in low temperature range (< 18.2°C). Specifically, PTB was significantly associated with ambient temperature and extreme heat/cold days during conception month and the third trimester. Sensitivity analysis indicated that female fetus were more susceptible to the risk of ambient temperature. Our study indicates that the risk of preterm birth due to high or low temperature may exist early during the conception month. [ABSTRACT FROM AUTHOR]

Background Pneumonia has been widely recognized as the leading cause of death in children worldwide, but its etiology still remains unclear. Objective We examined the association between maternal exposure to ambient air temperature during pregnancy and lifetime pneumonia in the offspring. Methods We conducted a cohort study of 2598 preschool children aged 3–6 years in Changsha, China. The lifetime prevalence of pneumonia was assessed using questionnaire. We backwards estimated each child's exposure to air temperature during prenatal and postnatal periods. Multiple regression model was used to examine the association between childhood pneumonia and exposure to air temperature in terms of odd ratios (OR) and 95% confidence interval (CI). Results Prevalence of childhood pneumonia in Changsha was high up to 38.6%. We found that childhood pneumonia was significantly associated with prenatal exposure to air temperature, with adjusted OR (95% CI) = 1.77 (1.23–2.54) for an interquartile range (IQR) increase in temperature, particularly during the second trimester with adjusted OR (95% CI) = 2.26 (1.32–3.89). Boys are more susceptible to the risk of pneumonia due to air temperature than girls. We further observed that maternal exposure to extreme heat days during pregnancy increased the risk of pneumonia in the offspring. Conclusions Maternal exposure to air temperature during pregnancy, particularly the second trimester, was associated with pneumonia in the children, providing the evidence for fetal origins of pneumonia. [ABSTRACT FROM AUTHOR]

Airborne particulate matter pollution has been linked to occurrence of childhood allergic rhinitis (AR). However, the relationships between exposure to particulate matter with an aerodynamic diameter ≤1 μm (PM 1) during early life (in utero and first year of life) and the onset of childhood AR remain largely unknown. This study aims to investigate potential associations of in utero and first-year exposures to size-segregated PMs, including PM 1 , PM 1–2.5 , PM 2.5 , PM 2.5–10 , and PM 10 , with childhood AR. We investigated 29286 preschool children aged 3–6 years in 7 Chinese major cities during 2019–2020 as the Phase II of the China Children, Families, Health Study. Machine learning-based space-time models were utilized to estimate early-life residential exposure to PM 1 , PM 2.5 , and PM 10 at 1 × 1-km resolutions. The concentrations of PM 1–2.5 and PM 2.5–10 were calculated by subtracting PM 1 from PM 2.5 and PM 2.5 from PM 10 , respectively. Multiple mixed-effects logistic models were used to assess the odds ratios (ORs) and 95% confidence intervals (CIs) of childhood AR associated with per 10-μg/m3 increase in exposure to particulate air pollution during in utero period and the first year of life. Among the 29286 children surveyed (mean ± standard deviation, 4.9 ± 0.9 years), 3652 (12.5%) were reported to be diagnosed with AR. Average PM 1 concentrations during in utero period and the first year since birth were 36.3 ± 8.6 μg/m3 and 33.1 ± 6.9 μg/m3, respectively. Exposure to PM 1 and PM 2.5 during pregnancy and the first year of life was associated with an increased risk of AR in children, and the OR estimates were higher for each 10-μg/m3 increase in PM 1 than for PM 2.5 (e.g., 1.132 [95% CI: 1.022–1.254] vs. 1.079 [95% CI: 1.014–1.149] in pregnancy; 1.151 [95% CI: 1.014–1.306] vs. 1.095 [95% CI: 1.008–1.189] in the first year of life). No associations were observed between AR and both pre- and post-natal exposure to PM 1–2.5 , indicating that PM 1 rather than PM 1–2.5 contributed to the association between PM 2.5 and childhood AR. In trimester-stratified analysis, childhood AR was only found to be associated with exposure to PM 1 (OR = 1.077, 95% CI: 1.027–1.128), PM 2.5 (OR = 1.048, 95% CI: 1.018–1.078), and PM 10 (OR = 1.032, 95% CI: 1.007–1.058) during the third trimester of pregnancy. Subgroup analysis suggested stronger PM-AR associations among younger (<5 years old) and winter-born children. Prenatal and postnatal exposures to ambient PM 1 and PM 2.5 were associated with an increased risk of childhood AR, and PM 2.5 -related hazards could be predominantly attributed to PM 1. These findings highlighted public health significance of formulating air quality guideline for ambient PM 1 in mitigating children's AR burden caused by particulate air pollution. • The first study evaluated early-life exposure to ambient PM 1 and childhood AR. • Increased childhood AR risk associated with prenatal and postnatal exposures to ambient PM 1 and PM 2.5. • Later trimesters of gestation might be the sensitive window for early-life PM exposure and childhood AR. • Enhanced effect of early-life PM exposure on childhood AR was observed among younger and winter-born children. [ABSTRACT FROM AUTHOR]