Explore the vast range of titles available.

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 PM 2.5 , PM 10 and NO 2 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 O 3 , all air pollutants demonstrated the lowest and highest concentrations in summertime and wintertime, respectively. The highest O 3 concentrations were found on weekend (weekend effect), whereas other ambient air pollutants had statistically significant (P < 0.05) daily variations in which higher concentrations were observed on weekdays compared to weekend (holiday effect). Hourly O 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 PM 2.5 was the responsible air pollutant in Tehran. Amongst meteorological factors, temperature was the key influencing factor for PM 2.5 and PM 10 concentrations, while nebulosity and solar radiation exerted major influences on ambient SO 2 and O 3 concentrations. Additionally, there is a moderate coupling between wind speed and NO 2 and CO concentrations.

The monthly and spatial variations of atmospheric dustfall (DF) and their elemental components were determined. The DF sampling was performed using the ASTM method D-1739 from April 2017 to March 2018 in four urban and suburb sampling sites around Tabriz, Iran. The ICP-OES was utilized for the determination of the elemental components of DF. The results showed that the level of DF varied from 1.3 to 27.6 (8.0 ± 3.4) g/m 2 .month during the sampling period, and the level of DF was higher in warm seasons than cold seasons. Also, it was revealed that the mean DF has a direct and significant relationship with temperature, wind speed, and relative humidity. The elements of Fe (11,997–17,093 mg/Kg and 71–81%) and Al (2903–6852 mg/Kg and 14–25%), which are the main elements of the Earth crust, were the dominant metals of DF among the analyzed elements. The lowest average value of the enrichment factor (EF) was for Al and was < 1, while the highest EF belonged to Hg, Pb, Cu, Sr, Mn, Co, Ni, and Cr, which were > 10 in all the sites, indicating that anthropogenic emission sources spread a considerable amount of trace elements in DF compared to the Lake Urmia bed or soil. The EF values for various elements (except than Cu and Hg) in cold seasons considerably increased compared to warm seasons. In all the study sites, Fe (540–1307 mg/m 2 .yr) had the highest deposition rates among the metals. This study revealed that the Earth crust is the main source of DF in the region.

Despite the frequent occurrence of heat waves in the Middle East, there is a lack of evidence regarding the overall estimates for the effect of heat waves on mortality in this region. This study aimed to review the effect of exposure to heat and cold waves and daily cause-specific mortality. Four electronic databases were searched. The titles, abstracts, and full-texts of the articles were carefully reviewed by two researchers. Once eligible studies were identified, the required data were extracted. Separate meta-analyses were conducted based on gender, age group, and health endpoint combinations. According to the meta-analysis, heat waves had a statistically significant effect on all-cause mortality with an RR of 1.23 (CI 95%: 1.08, 1.39). Cardiovascular mortality significantly increased in heat waves with an RR of 1.08 (CI 95%: 1.05, 1.10). However, the increase in respiratory mortality was not statistically significant. Compared to young people (age < 65 years old) and women, elderly and men were more vulnerable to heat waves with RRs of 1.31 (95% CI: 1.05, 1.57) and 1.33 (95% CI: 1.08, 1.58), respectively. This study can be beneficial in developing response or adaptation plans for heat waves. Future studies should focus on other specific health endpoints like ischemic heart disease, chronic obstructive pulmonary diseases, etc., and other outcomes such as hospitalization and emergency visits.

Respirator face masks (RFMs) as a personal-level intervention is increasingly being utilized to reduce ambient particulate matter (PM) exposure, globally. We tested the effectiveness of 50 commercially available ones in reducing the exposure of ambient particle number concentrations (PNC), PM10, PM2.5, and PM1 (PM ≤ 10, 2.5, and 1 μm in diameter, respectively) in a traffic-affected urban site in Tehran. To examine the efficiency of RFMs, we applied a specific experimental setup including vacuum pumps, dummy heads, connecting tubes, glass chambers, and GRIMM Aerosol Spectrometer to measure all metrics after dummy heads. The average effectiveness of RFMs was in the range of 0.7–83.5%, 3.5–68.1%, 0.8–46.1%, and 0.4–32.2% in reducing ambient PNC, PM10, PM2.5, and PM1, respectively. Considering all metrics, the highest effectiveness was observed always for Biomask, followed by 3 M 9332, due to their well-designed physical characteristics (e.g., adjustable nose clip for any face/nose shape, and size, soft inner material in the nose panel to provide a secure seal against leakage, adjustable or elasticated straps/ear loops to better adjust on any face). Biomask reduced ambient PM10 with a mean value of 94.6 μg m−3 (minimum–maximum: 51.7–100.3 μg m−3), whereas it filtered on average just 29.0 μg m−3 (25.7–43.5 μg m−3) of ambient PM2.5 and 18.2 μg m−3 (14.7–21.8 μg m−3) of PM1. A fuzzy analytical hierarchy process to find the most important design-related factors of RFMs affecting their effectiveness, which showed the exhalation valve and its diaphragm (20.4%), nose clip (19.7%), and cheek flaps (18.6%) are ranked as the main design-related variables. The fuzzy technique for order preference by similarity to ideal solution indicated that Biomask and 3M 9332 had scores of 1 and 0.97, the highest scores compared with other RFMs. This study provides crucial evidence-based results to elucidate the effectiveness and design-related factors of RFMs in real-environmental circumstances.

We estimated mortality and economic loss attributable to PM 2·5 air pollution exposure in 429 counties of Iran in 2018. Ambient PM 2.5 -related deaths were estimated using the Global Exposure Mortality Model (GEMM). According to the ground-monitored and satellite-based PM 2.5 data, the annual mean population-weighted PM 2·5 concentrations for Iran were 30.1 and 38.6 μg m −3 , respectively. We estimated that long-term exposure to ambient PM 2.5 contributed to 49,303 (95% confidence interval (CI) 40,914–57,379) deaths in adults ≥ 25 yr. from all-natural causes based on ground monitored data and 58,873 (95% CI 49,024–68,287) deaths using satellite-based models for PM 2.5 . The crude death rate and the age-standardized death rate per 100,000 population for age group ≥ 25 year due to ground-monitored PM 2.5 data versus satellite-based exposure estimates was 97 (95% CI 81–113) versus 116 (95% CI 97–135) and 125 (95% CI 104–145) versus 149 (95% CI 124–173), respectively. For ground-monitored and satellite-based PM 2.5 data, the economic loss attributable to ambient PM 2.5 -total mortality was approximately 10,713 (95% CI 8890–12,467) and 12,792.1 (95% CI 10,652.0–14,837.6) million USD, equivalent to nearly 3.7% (95% CI 3.06–4.29) and 4.3% (95% CI 3.6–4.5.0) of the total gross domestic product in Iran in 2018.

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has indirectly produced both positive and negative effects on the environment, particularly in terms of air quality. Our study aimed to determine these effects in the city of Tehran by comparing the ambient PM 2.5 and PM 10 levels recorded at 22 air quality monitoring stations during the outbreak (20 February–2 April 2020) with those from the corresponding period last year (20 February–3 April 2019). Contrary to expectation, the average concentrations of both the PM 2.5 and the PM 10 were markedly higher during the former, increasing by 20.5% and 15.7%, respectively, for the first month of the outbreak (20 February–19 March 2020) and by 23.5% and 20.0% for the subsequent Nowruz New Year holidays (from late March till early April), which resulted in overall increases of 20.5% and 16.5% for the entire period. The non-integrated responses to the pandemic, including the failure to close administrative centers and, in particular, the recommendation to maintain social distancing by reducing public transportation use (prompting citizens to travel by private vehicle), have worsened the ambient air quality in Tehran, providing an exceptional opportunity to evaluate the direct/indirect influence of air quality policies and emission control measures on PM 2.5 and PM 10 . Because of the significant association between the lethality of coronavirus disease 2019 (COVID-19) and exposure to ambient air pollution, the rise in airborne PM 2.5 during this outbreak may increase the mortality rate of SARS-CoV-2.

The main aims of the present research were (1) investigation of the temporal trends of atmospheric benzene concentrations in Tehran city during the period 2010 to 2013 and (2) assessment of carcinogenic and non-carcinogenic health risks of inhalation exposure to benzene. For the first objective, the data of ambient air benzene concentrations were derived from 15 air quality monitoring stations (AQMSs) in Tehran during the years 2010 to 2013 and they were temporally investigated after data cleaning and missing data imputation. The excess lifetime cancer risk (ELCR) and hazard quotient (HQ) were estimated to reveal the carcinogenic and non-carcinogenic health effects of exposure to ambient benzene. Our findings indicated that over 2010–2013, annual mean concentrations of benzene were in the range of 1.84 to 2.57 μg m −3 , and the highest annual mean concentration was observed in 2011 with a mean of 2.57 μg m −3 . The four-year average concentration of benzene during the period from 2010 to 2013 was 2.14 μg m −3 . Furthermore, the HQ for inhalation exposure to ambient benzene was lower than the acceptable risk level (HQ < 1) over the study time period which indicated that the non-carcinogenic effects are very unlikely to happen. In addition, health risk assessment for ELCR showed that the potential cancer risk for inhalation exposure to benzene was 1.67 × 10 −5 over the study period, which is significantly higher than the limits recommended by the U.S. EPA (1 × 10 −6 ). Our study clearly proves that the ambient benzene concentration in Tehran has substantially higher carcinogenic effects on the population. Appropriate sustainable control measures should be taken to reduce air benzene concentration and protect public health.

In this study, atmospheric concentrations of particulate-bound polycyclic aromatic hydrocarbons (PAHs) in Tehran megacity were determined to investigate the concentration, distribution, and sources of PAHs in PM₁₀. The health risk from exposure to airborne BaPeq through inhalation pathway was also assessed. Toxic equivalency factors (TEFs) approach was used for quantitative risk estimate, and incremental lifetime cancer risk (ILCR) was calculated. PM₁₀ samples were collected at ten sampling locations during the summer 2013 and winter 2014 by using two independent methods of field sampling. The PM₁₀ concentration in winter (89.55 ± 15.56 μg m⁻³) was 1.19 times higher than that in summer (75.42 ± 14.93 μg m⁻³). Sixteen PAHs were measured with the total average concentrations of PAHs ranged from 56.98 ± 15.91 to 110.35 ± 57.31 ng m⁻³ in summer and from 125.87 ± 79.02 to 171.25 ± 73.94 ng m⁻³ in winter which were much higher than concentrations measured in most similar studies conducted around the world. Molecular diagnostic ratios were used to identify PAH emission sources. The results indicated that gasoline-driven vehicles are the major sources of PAHs in the study area. Risk analysis showed that the mean and 90 % probability estimated inhalation ILCRs were 7.85 × 10⁻⁶ and 16.78 × 10⁻⁶, respectively. Results of a sensitivity analysis indicated that BaP concentration and cancer slope factor (CSF) contributed most to effect on ILCR mean.

This randomized crossover trial sought to determine whether wearing a high-efficiency particulate-filtering respirator (PFR) improves cardiovascular function over 48 h among healthy college students in Tehran. This trial was conducted from February 14th to 23rd, 2019 and twenty-six participants completed two 48-h intervention periods. Brachial blood pressure (BP) measured by 24-h ambulatory monitoring was the primary health outcome. Secondary outcomes included 48-h heart rate variability (HRV) indices, high-sensitive cardiac troponin (hs-TnT) and other biomarkers. The participants wore the PFR between 10.2 and 11.1 h while awake during the interventions. More than 80% of participants reported increased respiratory resistance while wearing the PFR due to a lack of an exhalation valve. There were no significant differences in brachial BP levels between subjects who wore PFR respirator and those did not. Except for high frequency (HF) power and heart rate (HR), no significant differences between interventions were observed for other HRV metrics. Wearing the PFR led to an increase of 66.0 ms2 (95% confidence interval [CI], 9.6–110.5) and 79.6 ms2 (95% CI, 19.0–140.1) in HF power during the first day when the two groups of participants wore the PFR. Night-time HR was significantly increased during the PFR intervention period. Other secondary outcomes were not significantly different between interventions. It is plausible that incomplete exposure reduction due to wearing the PFR less than half of the time or increased respiratory resistance mitigated potential health benefits. Additional trials are warranted to validate the CV protection of wearing PFRs in heavily-polluted cities.

Objectives: National ambient air quality standards (NAAQS) are critical tools for controlling air pollution and protecting public health. We designed this study to 1) gather the NAAQS for six classical air pollutants: PM 2.5 , PM 10 , O 3 , NO 2 , SO 2 , and CO in the Eastern Mediterranean Region (EMR) countries, 2) compare those with the updated World Health Organizations Air Quality Guidelines (WHO AQGs 2021), 3) estimate the potential health benefits of achieving annual PM 2.5 NAAQS and WHO AQGs per country, and 4) gather the information on air quality policies and action plans in the EMR countries. Methods: To gather information on the NAAQS, we searched several bibliographic databases, hand-searched the relevant papers and reports, and analysed unpublished data on NAAQS in the EMR countries reported from these countries to the WHO/Regional office of the Eastern Mediterranean/Climate Change, Health and Environment Unit (WHO/EMR/CHE). To estimate the potential health benefits of reaching the NAAQS and AQG levels for PM 2.5 , we used the average of ambient PM 2.5 exposures in the 22 EMR countries in 2019 from the Global Burden of Disease (GBD) dataset and AirQ+ software. Results: Almost all of the EMR countries have national ambient air quality standards for the critical air pollutants except Djibouti, Somalia, and Yemen. However, the current standards for PM 2.5 are up to 10 times higher than the current health-based WHO AQGs. The standards for other considered pollutants exceed AQGs as well. We estimated that the reduction of annual mean PM 2.5 exposure level to the AQG level (5 μg m −3 ) would be associated with a decrease of all natural-cause mortality in adults (age 30+) by 16.9%–42.1% in various EMR countries. All countries would even benefit from the achievement of the Interim Target-2 (25 μg m −3 ) for annual mean PM 2.5 : it would reduce all-cause mortality by 3%–37.5%. Less than half of the countries in the Region reported having policies relevant to air quality management, in particular addressing pollution related to sand and desert storms (SDS) such as enhancing the implementation of sustainable land management practices, taking measures to prevent and control the main factors of SDS, and developing early warning systems as tools to combat SDS. Few countries conduct studies on the health effects of air pollution or on a contribution of SDS to pollution levels. Information from air quality monitoring is available for 13 out of the 22 EMR countries. Conclusion: Improvement of air quality management, including international collaboration and prioritization of SDS, supported by an update (or establishment) of NAAQSs and enhanced air quality monitoring are essential elements for reduction of air pollution and its health effects in the EMR.