Search

This study systematically reviewed all the cohort studies investigating the relationship between long-term exposure to PM2.5 and any health outcome until February 2018. We searched ISI Web of Knowledge, Pubmed, and Scopus databases for peer-reviewed journal research articles published in English. We only extracted the results of the single-pollutant main analysis of each study, excluding the effect modifications and sensitivity analyses. Out of the initial 9523 articles, 203 articles were ultimately included for analysis. Based on the different characteristics of studies such as study design, outcome, exposure assessment method, and statistical model, we calculated the number and relative frequency of analyses with statistically significant and insignificant results. Most of the studies were prospective (84.8%), assessed both genders (66.5%), and focused on a specific age range (86.8%). Most of the articles (78.1%) had used modeling techniques for exposure assessment of cohorts’ participants. Among the total of 317 health outcomes, the most investigated outcomes include mortality due to cardiovascular disease (6.19%), all causes (5.48%), lung cancer (4.00%), ischemic heart disease (3.50%), and non-accidental causes (3.50%). The percentage of analyses with statistically significant results were higher among studies that used prospective design, mortality as the outcome, fixed stations as exposure assessment method, hazard ratio as risk measure, and no covariate adjustment. We can somehow conclude that the choice of right characteristics for cohort studies can make a difference in their results.

We conducted this systematic review to identify and appraise studies investigating the coronavirus disease 2019 (COVID-19) effect on ambient air pollution status worldwide. The review of studies was conducted using determined search terms via three major electronic databases (PubMed, Web of Science, and Scopus) according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach. A total of 26 full-text studies were included in our analysis. The lockdown measures related to COVID-19 pandemic caused significant decreases in the concentrations of PM2.5, NO2, PM10, SO2 and CO globally in the range of 2.9%–76.5%, 18.0%–96.0%, 6.0%–75.0%, 6.8%–49.0% and 6.2%–64.8%, respectively. However, O3 concentration increased in the range of 2.4%–252.3%. The highest decrease of PM2.5 was found in 16 states of Malaysia (76.5%), followed by Zaragoza (Spain) with 58.0% and Delhi (India) with 53.1%. The highest reduction of NO2 was found in Sale city (Morocco) with 96.0%, followed by Mumbai (India) with 75.0%, India with 70.0%, Valencia (Spain) with 69.0%, and Sao Paulo (Brazil) with 68.0%, respectively. The highest increase of O3 was recorded for Milan (Italy) with 252.3% and 169.9% during the first and third phases of lockdown measures, and for Kolkata (India) with 87% at the second phase of lockdown measures. Owing to the lockdown restrictions in the studied countries and cities, driving and public transit as a proxy of human mobilities and the factors affecting emission sources of ambient air pollution decreased in the ranges of 30–88% and 45–94%, respectively. There was a considerable variation in the reduction of ambient air pollutants in the countries and cities as the degree of lockdown measures had varied there. Our results illustrated that the COVID-19 pandemic had provided lessons and extra motivations for comprehensive implementing policies to reduce air pollution and its health effects in the future.

BACKGROUND: Despite frequent warnings of irreversible side effects of smoking in public media, the consumption of cigarette is increasing dramatically in both developed and developing countries. Cigarette smoke contains different kinds of chemicals, which all capable of inducing free radical production. There are studies supporting the idea that these free radicals have adverse effects in body and causing oxidative stress. Total antioxidant capacity (TAC) is considered as the total effect of all antioxidants and total oxidant status (TOS) shows the total effect of all oxidants existing in body fluids. Therefore, this research focused on the measurement and comparison of these markers in the serum of university students. METHODS: This study designed to determine the total antioxidant capacity, total oxidant status and oxidative stress index levels in the serum of active smokers, passive smokers and non-smokers in university students. A total of 150 participants were included in the study. The study population consisted of 50 smokers, 50 passive smokers and 50 nonsmokers. In serum samples, the levels of TAC and TOS were measured by spectrophotometric method using Rel Assay Diagnostics kit. Oxidative stress index was calculated through the TOS/TAC formula in three groups. RESULTS: The mean value TAC levels in serum samples of the three groups of smokers, passive smokers and nonsmokers were 1.096, 1.220 and 1.844 mmol Trolox equivalent/L, respectively, which were significantly greater in nonsmokers than smokers and passive smokers. The mean value TOS levels in serum samples of the three groups of smokers, passive smokers and nonsmokers were 13.747, 11.099 and 7.6510 µmol H2O2 equivalent/L, respectively, which were significantly lower in nonsmokers than two other groups. OSI values in smokers and passive smokers were significantly higher than the control group. CONCLUSIONS: According to our findings, the antioxidant capacity in all smokers (active and inactive) was less than the control group (non-smokers). The results of this study showed that smoking reduces the activity of the antioxidant defense system and activates the oxidative stress system in the body. Based on these findings, it can be clearly concluded that the decrease in antioxidant capacity in smokers is associated with increased production of oxidants and free radicals.

In this study, human exposure to benzene, toluene, ethylbenzene, xylenes (BTEX), along with their respective risk assessment is studied in four major units (n = 14-point sources) of the largest municipal solid waste management facilities (MSWF) in Iran. The results were compared with four urban sites in Tehran, capital of Iran. Workers at the pre-processing unit are exposed to the highest total BTEX (151 μg m−3). In specific, they were exposed to benzene concentrations of 11 μg m−3. Moreover, the total BTEX (t-BTEX) concentrations measured over the conveyor belt was 198 μg m−3 at most, followed by trommel (104), and active landfills (43). The mean concentration of ambient t-BTEX in Tehran is 100 μg m−3. On average, xylenes and toluene have the highest concentrations in both on-site and urban environments, with mean values of 24 and 21, and 41 and 37 μg m−3, respectively. Even though the non-carcinogenic risk of occupational exposure is negligible, BTEX is likely to increase the chance of carcinogenic risks (1.7E-05) for workers at the pre-processing unit. A definite carcinogenic risk of 1.3E-04, and non-carcinogenic effect, of HI = 1.6 were observed in one urban site. With the exception of the pre-processing unit, the citizens of Tehran had higher exposure to BTEX. Overall, BTEX concentrations in the largest MSWF of Iran remains an issue of public health concern.

We investigated temporal variations of ambient air pollutants and the influences of meteorological parameters on their concentrations using a robust method; convergent cross mapping; in Tehran (2012–2017). Tehran citizens were consistently exposed to annual PM2.5, PM10 and NO2 approximately 3.0–4.5, 3.5–4.5 and 1.5–2.5 times higher than the World Health Organization air quality guideline levels during the period. Except for O3, all air pollutants demonstrated the lowest and highest concentrations in summertime and wintertime, respectively. The highest O3 concentrations were found on weekend (weekend effect), whereas other ambient air pollutants had statistically significant (P 3 concentration reached its peak at 3.00 p.m., though other air pollutants displayed two peaks; morning and late night. Approximately 45% to 65% of AQI values were in the subcategory of unhealthy for sensitive groups and PM2.5 was the responsible air pollutant in Tehran. Amongst meteorological factors, temperature was the key influencing factor for PM2.5 and PM10 concentrations, while nebulosity and solar radiation exerted major influences on ambient SO2 and O3 concentrations. Additionally, there is a moderate coupling between wind speed and NO2 and CO concentrations.

Disinfection is a practice that inactivates and destroys pathogenic organisms. The conventional disinfectants for water and treated wastewater effluents have defects such as dangerous disinfection by-products, the resistance of bacteria and the related biofilms to disinfectant, high costs, no residual disinfecting action, and high risks involved in producing, transporting, and handling a large amount of chlorine and ozone. Accordingly, investigating new disinfection alternatives has been a necessity. Bacteriophages are used to treat a bacterial infection, which is known as phage therapy. In the recent decades, some studies revealed the role of phages in water and wastewater treatment, especially dis-infection. In addition, the abundance of phages specific to enteric bacterial pathogens in natural water bodies is disclosed in many studies. This review discusses the phages specified to fecal coliform and other waterborne bacteria, the main advantages for applying the phages to reduce pathogens, restrictions of disinfection using phages, and the prospective applications of phages in order to improve the design and operation of the treatment plants. Keywords:Disinfection; Bacteriophage; Pathogen; Water; Wastewater

The impact of bioaerosols in municipal solid waste management is nowadays identified as a growing health concern worldwide. In this study, exposure to endotoxin in composting facilities and its association with lung function and clinical symptoms was investigated in Tehran municipal solid waste management complex (Aradkooh) as one of the largest solid waste management facilities in the Middle East. Airborne endotoxins were collected between June and July 2019 and the concentrations were determined by Limulus Amebocyte Lysate (LAL) method. Healthy workers with no history of respiratory disease were recruited and data on clinical symptoms (cough, phlegm, wheezing, dyspnea, fatigue, headache, eye irritation, runny nose, runny eyes, and sore throat) was obtained by the modified American Thoracic Society questionnaire, and spirometric measurement was performed by an expert. The binary logistic regression test was used and adjusted for confounding variables. The results didn't show any difference in lung function parameters (FEV1, FVC, FEV1/FVC, PEF, FEF25-75%), and most of the respiratory symptoms despite a relatively high difference in the concentration of endotoxin observed in air samples of different locations. Only the increased risk of cough (OR 10.5, 95% CI: 2.4 to 44.8 in the moderately exposed group and 7.8, 95% CI: 1.6 to 39.1 in highly exposed ones), fatigue (OR 3.7, 95% CI: 1.2 to 11.7), and headache (OR 6.02, 95% CI: 1.4 to 24.5) were found in the exposed groups compared to controls after adjusting for age, active and passive smoking. However, findings of the study might be underestimated due to some issues including healthy worker effect, intra and intersubject variability, and self-reporting bias, thereby the results should be interpreted with caution. Although we did not find any relationship, due to the high concentrations of endotoxins observed in some sites, it is recommended to consider some possible prevention measures such as using personal protective equipment to reduce the exposure of workers at an acceptable level.

ADHD is a common neurodevelopmental disorder highly attributed to genetics, but the combination of other social and environmental determinants, as well as potential gene-environment interactions, can also be responsible. This paper aims to review relevant literature published up to April 2018 for determining whether air pollution caused by ambient gaseous (NO2, SO2, PCDD/Fs, Benzene) and particulate matters (PM10, PM2.5, PM7, PAH, BC/EC) as an environmental risk factor is associated with increased risk of ADHD in children. Relevant literature was identified through electronic searches of PubMed, Embase, Web of Science, Scopus database and gray literature. A total of 872 articles were initially identified 28 of which meeting the defined inclusion criteria were included. The methodological quality of the included articles was evaluated using the modified Critical Appraisal Skills Programs (CASP) and confounding variables, exposure and outcome measurement were assessed. The results of this systematic review revealed that there is more evidence on the detrimental effects of EC, BC, and PM on ADHD compared to PAH. Among gaseous air pollutants, association was found between SO2 and urinary level of t,t-MA (trans, trans-muconic acid) as a proxy-biomarker of NO2 exposure, not merely benzene. However few studies related to NO2 (0.46%) found detrimental effects. Overall, the number of studies reporting an association between air pollution and increased risk of ADHD is relatively higher compared to the number of studies reporting no association. However, the findings of the studies provided limited evidence to support the idea that exposure to air pollution may be linked to increased risk of ADHD. Well-designed and harmonized studies considering standard methods for individual exposure assessment, critical windows of susceptibility, and appropriate tools for outcome measurement, can improve the quality of epidemiological studies and strengthen the evidence. Since ADHD with its long-term consequences can impose large costs to communities and impact the children performance, determination of the risk factors in children and particularly the role of the environment as priorities for research should be considered.

Some recent human and animal studies have suggested that air pollution may affect the central nervous system and contribute to neurodevelopmental outcomes, such as autism spectrum disorder (ASD). We aimed to investigate the association between long-term exposure to ambient air pollution and increased odds of ASD among 2 to 10-year-old children. We conducted a case-control study in Tehran, Iran. Cases were 134 children born between 2004 and 2012 diagnosed with ASD whose mothers were resident in Tehran during their pregnancy, and controls were 388 children without ASD randomly selected from public schools and kindergartens. Land-use regression models were used to estimate their annual mean exposure to ambient particulate matter with aerodynamic diameter ≤10 μm (PM10), sulfur dioxide (SO2), benzene, toluene, ethylbenzene, p-xylene, o-xylene, m-xylene (BTEX), and total BTEX. Logistic regression was used for the analyses and adjusted for possible confounding variables. The odds ratios per 1 unit increase in pollutants in the adjusted models were 1.00 (95% CI: 0.99, 1.01) for PM10, 0.99 (95% CI: 0.99, 1.00) for SO2, 0.96 (0.83, 1.11) for benzene, 1.00 (0.96, 1.04) for toluene, 0.95 (0.79, 1.16) for ethylbenzene, 1.00 (0.78, 1.27) for p-xylene, 1.09 (0.94, 1.27) for o-xylene, 1.01 (0.92, 1.12) for m-xylene, and 0.99 (0.97, 1.01) for total BTEX. We did not find the evidence of association between estimated annual mean exposure to abovementioned ambient air pollutants and increased odds of ASD in children. However, our findings might be due to some important limitations. Further research with better control of confounding variables, improved spatiotemporal exposure estimates, and inclusion of other important markers of air pollution is recommended.

To investigate spatial inequality of ambient air pollutants and comparison of their heterogeneity and homogeneity across Tehran, the following quantitative indicators were utilized: coefficient of divergence (COD), the 90th percentile of the absolute differences between ambient air pollutant concentrations and coefficient of variation (CV). Real-time hourly concentrations of particulate matter (PM) and gaseous air pollutants (GAPs) of twenty-two air quality monitoring stations (AQMSs) were obtained from Tehran Air Quality Control Company (TAQCC) in 2017. Annual mean concentrations of PM2.5, PM10–2.5, and PM10 (PMX) ranged from 21.7 to 40.5, 37.3 to 75.0 and 58.0 to 110.4 μg m−3, respectively. Annual mean PM2.5 and PM10 concentrations were higher than the World Health Organization air quality guideline (WHO AQG) and national standard levels. NO2, O3, SO2 and CO annual mean concentrations ranged from 27.0 to 76.8, 15.5 to 25.1, 4.6 to 12.2 ppb, and 1.9 to 3.8 ppm over AQMSs, respectively. Our generated spatial maps exhibited that ambient PMX concentrations increased from the north into south and south-western areas as the hotspots of ambient PMX in Tehran. O3 hotspots were observed in the north and south-west, while NO2 hotspots were in the west and south. COD values of PMX demonstrated more results lower than the 0.2 cut off compared to GAPs; indicating high to moderate spatial homogeneity for PMX and moderate to high spatial heterogeneity for GAPs. Regarding CV approach, the spatial variabilities of air pollutants followed in the order of O3 (87.3%) > SO2 (65.2%) > CO (61.8%) > PM10–2.5 (52.5%) > PM2.5 (48.9%) > NO2 (48.1%) > PM10 (42.9%), which were mainly in agreement with COD results, except for NO2. COD values observed a statistically (P