[en] The exposure to heavy metals and polycyclic aromatic hydrocarbons (PAHs) bound to particulate matter 2.5 (PM_2.5) ambient air can result in some adverse health effect. In the current study, PM_2.5 ambient air of Tehran metropolitan, Iran, was characterized by the aid of scanning electron microscope and energy-dispersive X-ray techniques. Also, the human health risk of heavy metals and PAHs bound PM_2.5 for adults and children was assessed using the Monte Carlo simulation method. According to our findings, a size range of 0.97–2.46 μm with an average diameter of 1.56 μm for PM_2.5 was noted. The average concentration of PM_2.5 in ambient air (8.29E+04 ± 2.94E+04 ng m⁻³) significantly (p < 0.05) was suppressed the national (2.50E+04 ng m⁻³), World Health Organization (2.50E+04 ng m⁻³) and Environmental Protection Agency (3.50E+04 ng m⁻³) standard limits. The rank order of heavy metals bound PM_2.5 was determined as Al > Cu > Cd > Cr > Pb > Ni > Fe > Mn. The maximum concentration among 16 PAHs compounds investigated was correlated with Phenanthrene. Considering the principal component analysis, the main source of heavy metals (Ni, Pb and Cr) is vehicle combustion. Moreover, the rank order of exposure pathways based on their health risk was ingestion > inhalation > dermal contact. Moreover, the significant health risks for Tehran residents due to heavy metals bound PM_2.5 [target hazard quotient > 1; carcinogenic risk > 1.00E−06)] were noted based on the health risk assessment. Excessive carcinogenic risk (ECR) of PAHs bound PM_2.5 was 4.16E−07 that demonstrated that there is no considerable risk (ECR < 1.00E−06).

[en] As air pollution is a major problem in Tehran, this study aimed to investigate the physicochemical characterization of the water-soluble and organic contents of ambient PM_2.5 in Tehran and determine its in vitro toxicological impact on human lung epithelial cells (A549). A total of 11 sampling stations were selected, including three categories: traffic, urban, and suburban. All sampling was carried out in the spring and summer of 2015. Ion chromatography (IC), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and GC‐MS were used to analyze ionic compounds, heavy metals, and polycyclic aromatic hydrocarbons (PAHs), respectively, and an ELISA reader was used for cytotoxicity analysis. The most prevalent ionic species found for all three categories was SO₄²⁻. PAH concentrations were 43.45 ± 32.71, 50.51 ± 37.27, and 29.13 ± 33.29 ng/m³ for traffic, urban, and suburban stations, respectively. For all sampling stations, Al and Fe had the highest values among the investigated heavy metals. Cell viability measurements, carried out using the MTT assay, showed that all three categories of samples cause cytotoxicity, although the urban station samples showed higher cytotoxicity than those from the other stations (p Ë‚ 0.05). Based on the results of the present study, organic compounds and insoluble particles could be the main causes of cytotoxicity. - Highlights: • PM_2.5 at three sites in Tehran during the spring and summer were collected. • Chemical composition of PM_2.5 and the biological effects were investigated. • Cytotoxicity of PM_2.5 on human lung epithelial cells (A549) was investigated. • Organic extract fraction had severe cytotoxicity than water soluble extracts. • PM_2.5 cytotoxicity is due to the presence of PAH_S and heavy metals in PM_2.5

[en] Asbestos, as with other pollutants in the air, has adverse effects on the health of human beings and animals. Today, the relationship between presence of asbestos fibers in the air breathed by humans and developing serious diseases such as lung cancer (asbestosis) and mesothelioma has been proven. This study was designed and conducted within the time period of August 2017 and June 2018 to determine the concentration of asbestos fiber in the ambient air of Shahryar City and to evaluate their health effects for the general population of the city. For this purpose, samples were taken from four points, and overall 32 air samples were taken along the year. The samples were then analyzed by the phase contrast microscopy (PCM) method. Also, to investigate the type of asbestos and for more accurate counting of fibers, SEM analysis was utilized. Finally, based on the EPA IRIS method, the health effects resulting from asbestos risks were also evaluated. The results of this study indicated that the mean annual concentration of asbestos fiber in the ambient air of Shahryar City was obtained as 0.0019 f/ml PCM and 0.0072 f/ml SEM. Furthermore, the most polluted point was S1 point (0.0119 –0.0026 f/ml, PCM), while the lowest concentration was related to S4 point (0.001 f/ml PCM–0.0021 f/ml SEM). The mean annual risk resulting from airborne asbestos fiber in the ambient air of Shahryar City for all samples was obtained as 1.72 × 10⁻⁶ to 2.2 × 10⁻⁴, which was higher than the recommended risk range in some points.

[en] This study assessed and compared the carcinogenic risks and hazard ratios of exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) within different units of a municipal solid waste disposal facility (Tehran, Iran), including the leachate treatment plant (LTP), the landfill, and a composting unit. Eight stations within the landfill site were sampled during summer and winter using NIOSH method 1501. The health risk assessment was conducted using the probabilistic risk model Oracle Crystal Ball. The probability distributions of risks were estimated. The average concentrations (±SD) of benzene, toluene, ethylbenzene, xylene, and total BTEX were 9.01 (± 5.22), 11.44 (± 6.62), 14.56 (± 9.8), 24.06 (± 14.86), and 59.09 (± 32.38) ppbv, respectively. BTEX concentrations were significantly higher downwind of the disposal site compared to those in the upwind direction. The maximum carcinogenic risks of benzene in LTP, landfill, and composting unit were in excess of 1 × 10⁻⁴. Hazard ratios of BTEX were sufficiently low so as not to pose a significant risk to the workers’ health. However, maximum hazard ratios of benzene and total BTEX within landfill exceeded 1. In general, lifetime cancer risks and hazard ratios of BTEX were higher in landfill area compared to leachate treatment plant or the composting unit. Sensitivity analyses indicated that concentration and exposure duration had the largest impacts on the variance of the estimated risks. Individuals working in the landfill were at higher risk. An action plan is needed to reduce the risks from BTEX exposure in waste facilities by reducing the concentrations and/or exposure duration.

[en] This study characterized and quantified the bacterial and fungal bioaerosols in nine wards of the Razavi Hospital (Mashhad, Iran) that is equipped with an advanced heating, ventilating, and air conditioning (HVAC) system including HEPA filters for air cleaning. In this study, 432 samples were taken from the indoor air of multiple hospital wards during the morning and afternoon shifts during summer and autumn. The particle number concentrations with sizes of > 0.3, > 0.5, > 1, > 2, > 5, and > 10 μm were measured using a 6-channel handheld particle counter. A greater diversity of bioaerosol types were observed during the morning shifts and during summer. The microbial load was not affected significantly by the temperature, relative humidity, working shift, season, and number of visitors, indicating the effectiveness of a well-designed ventilation system to eliminate site-specific variations. For microbial number concentrations, a significant correlation was only observed between the number of particles with a diameter of > 10 μm and the airborne microbial loading. Thus, passive sampling may not properly reflect the actual concentrations of smaller bioaerosols. In conclusion, HEPA filters in the HVAC system successfully decreased the bioaerosol concentrations in the hospital environment. Additionally, we recommend that active sampling be used in cases where a well-functioning HVAC system exists.

[en] Benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations were measured in beauty salons (BS) and in the urine of the beauty practitioners and a control group. Indoor and outdoor concentrations of BTEX were measured in 36 randomly selected salons. Before- and after-shift urinary BTEX were measured from one female non-smoker employee in each salon, and repeated three times. Clinical symptoms in that beautician were assessed by a physician. Thirty-six unexposed women were included as the control group. Cancer and non-cancer risks of exposure were assessed using deterministic and stochastic methods. Average indoor concentrations of BTEX were higher than those in the ambient air. Urinary BTEX concentrations in the beauty practitioners were significantly higher than in the control group. Linear regression showed that 77% of urinary benzene and toluene variations can be explained by their airborne concentrations. A positive significant relationship was found between age and urinary BTEX concentrations. Although the BTEX cancer and non-cancer risks were not significant, BTEX led to irritation of the eyes, throat, lung, and nose. In addition, toluene caused menstrual disorders among beauty practitioners. These results suggest that it is essential to decrease the exposure of beauty practitioners to BTEX compounds.

[en] Highlights: • Concentrations of 6 air pollutants were measured in taxis' cabin. • Effects of taxis' age and model, fuel, and refueling were investigated. • Refueling increased concentrations of pollutants for CNG and LPG fuels. • BTEX concentrations in all vehicle models were significantly higher for gasoline. • Vehicle age inversely affected formaldehyde and acetaldehyde. The air pollutant species and concentrations in taxis' cabins can present significant health impacts on health. This study measured the concentrations of benzene, toluene, ethylbenzene, xylene (BTEX), formaldehyde, and acetaldehyde in the cabins of four different taxi models. The effects of taxi's age, fuel type, and refueling were investigated. Four taxi models in 3 age groups were fueled with 3 different fuels (gas, compressed natural gas (CNG), and liquefied petroleum gas (LPG)), and the concentrations of 6 air pollutants were measured in the taxi cabins before and after refueling. BTEX, formaldehyde, and acetaldehyde sampling were actively sampled using NIOSH methods 1501, 2541, and 2538, respectively. The average BTEX concentrations for all taxi models were below guideline values. The average concentrations (±SD) of formaldehyde in Model 1 to Model 4 taxis were 889 (±356), 806 (±323), 1144 (±240), and 934 (±167) ppbv, respectively. Acetaldehyde average concentrations (±SD) in Model 1 to Model 4 taxis were 410 (±223), 441 (±241), 443 (±210), and 482 (±91) ppbv, respectively. Refueling increased the in-vehicle concentrations of pollutants primarily the CNG and LPG fuels. BTEX concentrations in all taxi models were significantly higher for gasoline. Taxi age inversely affected formaldehyde and acetaldehyde. In conclusion, it seems that refueling process and substitution of gasoline with CNG and LPG can be considered as solutions to improve in-vehicle air concentrations for taxis.