Temporal variations of atmospheric benzene and its health effects in Tehran megacity (2010-2013)

Climatic conditions and concentrations of BTEX compounds in atmospheric media

Climatic and meteorological conditions are among the factors affecting the ambient concentrations of BTEX compounds. This systematic review and meta-analysis aimed to interrogate the seasonal effect of climatic conditions on the concentrations of BTEX compounds. Three electronic bibliographic databases including Scopus, PubMed, and Web of Science were systematically searched up to November 14, 2023. The search algorithm followed PRISMA guidance and consisted of three groupings of keywords and their possible combinations. For various climatic conditions, the overall mean and 95% confidence interval (CI) of effect size related to BTEX concentrations were calculated using a random-effect model. In total, 104 articles were included for evaluation in this review. BTEX ambient concentration was higher in winter (ranging from 36 out of 79 relevant studies for xylene to 52 out of 97 relevant studies for benzene) followed by summer and autumn. For humidity conditions, the highest exposure values for BTEX were detected for rainy weather (ranging from 3 out of 5 relevant studies for toluene and xylene to 4 out of 5 relevant studies for benzene and ethyl benzene) compared to dry conditions. The pooled concentration (μg/m3) of benzene, toluene, ethyl benzene, and xylene were computed as 2.61, 7.12, 2.21, and 3.61 in spring, 2.13, 7.53, 1.61, and 2.75 in summer, 3.04, 9.59, 3.14, and 5.50 in autumn, and 3.56, 8.71, 2.35, and 3.91 in winter, respectively. Moreover, the pooled concentrations (μg/m3) of BTEX were measured as 2.98, 7.22, 1.90, and 3.03 in dry weather and 3.15, 6.30, 2.14, and 3.86 in rainy or wet weather, respectively. In most seasons, the ambient concentrations of BTEX were higher in countries with low and middle incomes and in Middle Eastern countries and East/Southeast Asia compared to those in other regions (P < 0.001). The increasing concentrations of BTEX in winter and autumn followed by the summer season and during rainy/wet weather appear to be reasonably consistent despite variations in study methods, quality, or geography. Therefore, it is recommended that more serious control measures are considered for decreasing exposure to BTEX in these climatic conditions.

Benzene: A critical review on measurement methodology, certified reference material, exposure limits with its impact on human health and mitigation strategies

Benzene is a carcinogenic pollutant with significant emission sources present in the atmosphere. The need for accurate and precise measurement of benzene in the atmosphere has become increasingly evident due to its toxicity and the adverse health effects associated with exposure to different concentrations. Certified reference material (CRM) is essential to establish the traceability of measurement results. The present review compiles the available national and international measurement methods, certified reference materials (CRMs) for benzene and the limit of benzene in fuel composition (v/v) worldwide. Overall, the review indicates the benzene level in the atmosphere and the resulting impacts on the environment and human health, which frequently exceed the exposure limits of different environment regulatory agencies. An extensive literature review was conducted to gather information on monitoring and analysis methods for benzene, revealing that the most preferred method, i.e. Gas Chromatography- Flame Ionization Detector and Mass Spectrometry, is neither cost-effective nor suitable for real-time continuous monitoring. By analysing existing literature and studies, this review will shed light on the understanding of the importance of benzene pollution monitoring in ambient air and its implications for public health. Additionally, it will reflect the mitigation strategies applied by regulators & need for future revisions of air quality guidelines.

Assessment of health risk and burden of disease induced by exposure to benzene, toluene, ethylbenzene, and xylene in the outdoor air in Tehran, Iran

The health risk and burden of disease induced by exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) in the outdoor air in Tehran, 2019 were assessed based on the data of five fixed stations with weekly BTEX measurements. The non-carcinogenic risk, carcinogenic risk, and disease burden from exposure to BTEX compounds were determined by hazard index (HI), incremental lifetime cancer risk (ILCR), and disability-adjusted life year (DALY), respectively. The average annual concentrations of benzene, toluene, ethylbenzene, and xylene in the outdoor air in Tehran were 6.59, 21.62, 4.68, and 20.88 μg/m³, respectively. The lowest seasonal BTEX concentrations were observed in spring and the highest ones occurred in summer. The HI values of BTEX in the outdoor air in Tehran by district ranged from 0.34 to 0.58 (less than one). The average ILCR values of benzene and ethylbenzene were 5.37 × 10^-5 and 1.23 × 10^-5, respectively (in the range of probable increased cancer risk). The DALYs, death, DALY rate (per 100,000 people) and death rate (per 100,000 people) induced by BTEX exposure in the outdoor air in Tehran were determined to be 180.21, 3.51, 2.07, and 0.04, respectively. The five highest attributable DALY rates in Tehran by district were observed in the districts 10 (2.60), 11 (2.43), 17 (2.41), 20 (2.32), and 9 (2.32), respectively. The corrective measures such as controlling road traffic and improving the quality of vehicles and gasoline in Tehran could reduce the burden of disease from BTEX along with the health effects of other outdoor air pollutants.

A Study on the Gaseous Benzene Removal Based on Adsorption onto the Cost-Effective and Environmentally Friendly Adsorbent

Removal of benzene is essential for human and environmental health because it has toxic and hazardous properties at various concentrations. Theseneed to be effectively eliminated with carbon-based adsorbents. PASACs, carbon-based adsorbents obtained from using the needles of Pseudotsuga menziesii, were produced by optimized HCl- and H₂SO₄-impregnated approaches. Regarding physicochemical structure, the optimized PASAC23 and PASAC35 with surface areas of 657 and 581 m²/g and total pore volumes of 0.36 and 0.32 cm³/g showed ideal temperatures of 800 °C. In order to investigate and compare internal benzene removal efficiency, PASAC23 and PASAC35 were studied separately. Initial concentrations were found to range from 5 to 500 mg/m³, and between 25 and 45 °C. The removal rate of benzene by PASAC23 and PASAC35 was 97 and 94% at low concentrations, respectively. While the highest capture amount for PASAC23 and PASAC35 was found to be at 25 °C with 141 and 116 mg/g, the adsorption capacity decreased to 102 and 90 mg/g at 45 °C. The holding capacity decreased between 22.41 and 27.66% due to increasing temperatures. After five cycles of PASAC23 and PASAC35 regeneration, we found that they could remove 62.37 and 58.46% of benzene, respectively. These results confirmed that PASAC23 is a promising environmentally adsorbent for effectively removing benzene with a competitive yield.

Air pollution exposure and mammographic breast density in Tehran, Iran: a cross-sectional study

BACKGROUND

Air pollution is one of the major public health challenges in many parts of the world possibly has an association with breast cancer. However, the mechanism is still unclear. This study aimed to find an association between exposure to six criteria ambient air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, O₃, and CO) and mammographic breast density (MBD), as one of the strongest predictors for developing breast cancer, in women living in Tehran, Iran.

METHODS

Participants were selected from women attending two university hospitals for screening mammography from 2019 to 2021. Breast density was rated by two expert radiologists. Individual exposures to 3-year ambient air pollution levels at the residence were estimated.

RESULTS

The final analysis in 791 eligible women showed that low and high breast density was detected in 34.8 and 62.2 of participants, respectively. Logistic regression analysis after considering all possible confounding factors represented that an increase in each unit of NO₂ (ppb) exposure was associated with an increased risk of breast density with an OR equal to 1.04 (95CI: 1.01 to 1.07). Furthermore, CO level was associated with a decreasing breast density (OR = 0.40, 95CI = 0.19 to 0.86). None of the other pollutants were associated with breast density.

CONCLUSION

Higher MBD was associated with an increased level of NO₂, as a marker of traffic-related air pollution. Furthermore, CO concentration was associated with a lower MBD, while other criteria air pollutants were not related to MBD. Further studies are needed to evaluate the association between ambient air pollutants with MBD.

BTEX levels in rural households: Heating system, building characteristic impacts and lifetime excess cancer risk assessment

BTEX (benzene, toluene, ethylbenzene, and xylene) are a group of toxic organic compounds that exposure to them can cause adverse short and long terms health effects. We measured the levels of BTEX in the indoor and outdoor air of rural areas in Ardebil, Iran. We further assessed their health risks and determinants parameters. BTEX were sampled by drawing air through activated charcoal tubes, using low flow SKC pumps. Samples were extracted by adding carbon disulfide and analyzed by subjecting the aromatic fraction to GC-FID. The results indicated that the concentrations of BTEX in the indoor air were significantly higher than those of outdoor (p-value<0.05). The mean indoor concentrations of benzene, toluene, ethylbenzene, and xylene were 41.69 ± 30.70, 96.73 ± 60.75, 38.73 ± 33.59, and 59.42 ± 35.99 μg m^-3, while the mean outdoor concentrations of them were 8.94 ± 7.32, 36.93 ± 21.82, 7.66 ± 5.63, and 18.14 ± 10.25 μg m^-3, respectively. The concentrations of BTEX in indoor and outdoor of the rural areas that used kerosene fuel for heating systems were significantly higher than those used natural gas. The results indicated that the tobacco smoke is a notable temporary source of indoor BTEX. The mean inhalation lifetime cancer risk (LTCR) value of benzene for residents of rural houses with the natural gas and kerosene heating systems were 28.6 × 10^-6 and 97.2 × 10^-6, while for ethylbenzene these figures stood out at 29.1 × 10^-6 and 95.8 × 10^-6, respectively. LTCR value for residents who used kerosene fuel for heating was higher than the World Health Organization (WHO) recommended limit.

COVID-19 Impact on Public Health, Environment, Human Psychology, Global Socioeconomy, and Education

The end of the year 2019 was marked by the introduction of a third highly pathogenic coronavirus, after SARS-CoV (2003) and MERS-CoV (2012), in the human population which was officially declared a global pandemic by the World Health Organization (WHO) on March 11, 2020. Indeed, the pandemic of COVID-19 (Coronavirus Disease 19) has evolved at an unprecedented rate: after its emergence in Wuhan, the capital of the province of Hubei of the People's Republic of China, in December 2019, the total number of confirmed cases did not cease growing very quickly in the world. In this manuscript, we have provided an overview of the impact of COVID-19 on health, and we have proposed different nutrients suitable for infected patients to boost their immune systems. On the other hand, we have described the advantages and disadvantages of COVID-19 on the environment including the quality of water, air, waste management, and energy consumption, as well as the impact of this pandemic on human psychology, the educational system, and the global economy. In addition, we have tried to come up with some solutions to counter the negative repercussions of the pandemic.

Assessing BTEX concentrations emitted by hookah smoke in indoor air of residential buildings: health risk assessment for children

Hookah smoke is one of the major indoor sources of Volatile Organic Compounds (VOCs), including Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX). The present study aimed to investigate potential exposure to BTEX compounds among primary school children whose parents smoked hookah at home. BTEX concentrations in indoor air were measured in 60 residential buildings of Khesht, southwestern Iran (case = 30 and control = 30). Target compounds were sampled by charcoal tubes, and the samples were then analyzed by GC-FID. Monte Carlo simulation was used to assess the carcinogenic and non-carcinogenic risks of BTX exposure for the children aged 7-13 years. The concentrations of benzene (7.19 ± 3.09 vs. 0.82 ± 0.5 μg/m³), toluene (1.62 ± 0.69 vs. 0.3 ± 0.22 μg/m³), and xylenes (2.9 ± 1.66 vs. 0.31 ± 0.22 μg/m³) were considerably higher in the indoor air of the case houses compared with the control houses (p < 0.05). The Incremental Lifetime Cancer Risk (ILCR) of benzene for non-smoking and smoking houses were estimated 1.8 × 10^-6 and 15 × 10^-6, respectively, exceeding the recommendations of the World Health Organization (WHO) and the Environmental Protection Agency (EPA) (1 × 10^-6). Moreover, Hazard Quotients (HQs) of all BTX compounds were < 1. The indoor benzene concentration was significantly influenced by the floor at which families lived and type of the kitchen. In order to prevent children's exposure to BTX emitted by hookah, banning indoor smoking is the only way to eliminate these compounds in the indoor air.

The effect of COVID-19 pandemic on human mobility and ambient air quality around the world: A systematic review

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 PM_2.5, 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 PM_2.5 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 Salé city (Morocco) with 96.0%, followed by Mumbai (India) with 75.0%, India with 70.0%, Valencia (Spain) with 69.0%, and São 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.

Exposure to BTEX concentration and the related health risk assessment in printing and copying centers

This study was derived to investigation of BTEX (benzene, toluene, ethylbenzene, xylenes) concentrations in printing and copying centers (PCCs) in Ardabil city of Iran. Fifty-three PCCs were randomly selected from all the 136 number of PCCs and BTEX was sampled form their indoor air. The results showed that the concentration of BTEX in the indoor air PCCs is lower than the OELs (occupational exposure limit) in all cases. The obtained mean concentrations of benzene, toluene, ethylbenzene, and xylene were 93.6±63.2, 150.6±99.2, 34.3±16.8, and 29.5±15.2 μg/m³ respectively. Type of printer, number of printing and copying device, and type of ventilation system had significant influence on the BTEX concentration. The mean inhalation lifetime cancer risk (LTCR) value for benzene and ethylbenzene in the indoor air of the PCCs with LaserJet and inkjet printers was 44.4 × 10^-6 and 153.3 × 10^-6, and 23.4×10^-6 and 54.2× 10^-6, respectively, which were higher than EPA (Environmental Protection Agency) and World Health Organization (WHO) recommended limits. The hazard quotient (HQ) of benzene in the indoor air of the PCCs with inkjet printers was >1, which indicates that the non-carcinogenic risks associated with exposure to these compounds are considerable.

The Seasonality Impact of the BTEX Pollution on the Atmosphere of Arad City, Romania

Benzene, toluene, and total BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations registered for one year (2016) have been determined every month for one high-density traffic area. The assessment was performed in Arad City, Romania, to evaluate these pollutants and their influence on the inhabitants’ health. The contaminants were sampled using a static sampling method and analyzed by gas chromatography coupled with mass spectrometry. Benzene was the most dominant among the BTEX compounds—the average concentrations ranged from 18.00 ± 1.32 µg m⁻³ in December to 2.47 ± 0.74 µg m⁻³ in August. The average toluene concentration over the year was 4.36 ± 2.42 µg m⁻³ (with a maximum of 9.60 ± 2.39 µg m⁻³ in November and a minimum of 1.04 ± 0.29 µg m⁻³ in May). The toluene/benzene ratio (T/B) was around 0.5, indicating substantial contributions from mobile sources (vehicles). The emission and accumulation of different aromatic compounds (especially benzene) could deteriorate the urban air quality. The lifetime cancer risk (LTCR) for benzene was found to be more than 10⁻⁵ in winter, including the inhabitants in the “probable cancer risk” category.

Human, Forest and vegetation health metrics of ground-level ozone (SOMO35, AOT40f and AOT40v) in Tehran

PURPOSE

We aimed to investigate the spatial O₃ indices (SOMO35: annual sum of maximum daily 8-h ozone means over 35 ppb, AOT40: the accumulated exposure over an hourly threshold of 40 ppb during daylight hours between 8:00 and 20:00 in the growing seasons of plants) in Tehran (2019-2020).

METHODS

The data of ambient O₃ concentrations, measured at twenty-three regulatory ambient air quality monitoring stations (AQMSs) in Tehran, were obtained.

RESULTS

The annual mean O₃ concentrations were found to be 15.8-25.7 ppb; the highest and lowest annual mean concentration of ambient O₃ were observed in Shahrdari 22 and Shahr-e-Rey stations, respectively. Spatial distribution of exposure to O₃ across Tehran was in the range of 1.36-1.64; the highest O₃ concentrations were observed in the northern, west and south-western parts of Tehran, while the central and south areas of Tehran city experienced low to moderate concentrations. The indices of SOMO35, AOT40f and AOT40v across AQMSs in Tehran was in the range of 1830-6437 ppb. Days, 10,613-39,505 ppb.h and 4979-16,804 ppb.h, respectively. For Tehran city, the indices of SOMO35 and AOT40f were 4138 ppb. days and 27,556 ppb.h respectively. Our results revealed that the value of SOMO35 across AQMSs of Tehran was higher than the recommended target value of 3000 ppb. days.

CONCLUSIONS

To reduce O₃ pollution and its effects on both human and plants health, the governmental organizations should take appropriate sustainable control policies.

Background concentrations of benzene, potential long range transport influences and corresponding cancer risk in four cities of central Europe, in relation to air mass origination

Benzene concentrations covering the three year period 2015-2017, were derived from four background monitoring stations located in Berlin (Germany), Budapest (Hungary), Mons (Belgium) and Torino (Italy), in order to calculate the corresponding Incremental Lifetime Cancer Risk (ILCR) of an average adult, associated with the inhalation of benzene. In addition, a cluster analysis of backward air mass trajectories was coupled with Potential Source Contribution Function (PSCF) model aiming to identify possible exogenous source regions of benzene affecting the four cities and also to allocate the ILCR in atmospheric circulation patterns. A potential health risk (ILCR>10^-6) from benzene exposure was estimated in all four cities. In Berlin and Mons, an enhanced fraction of the ILCR was associated with Southeast short range trajectories of slow moving air masses, which were also related to extreme long range transport episodes. Furthermore, increased benzene concentrations in Budapest were observed during the prevalence of short range Southwest airflows, whilst PSCF model isolated the transboundary emission sources in the industrialized North Italy. Long range trajectories of fast moving marine air masses from North Atlantic, not influenced by anthropogenic emissions, improved the benzene related air quality in Berlin and Mons due to dispersion. No long range transport effects were confirmed in Torino.

Observations of BTEX in the ambient air of Kuala Lumpur by passive sampling

Benzene, toluene, ethylbenzene and xylenes (BTEX) are well known hazardous volatile organic compounds (VOCs) due to their human health risks and photochemical effects. The main objective of this study was to estimate BTEX levels and evaluate interspecies ratios and ozone formation potentials (OFP) in the ambient air of urban Kuala Lumpur (KL) based on a passive sampling method with a Tenax® GR adsorbent tube. Analysis of BTEX was performed using a thermal desorption (TD)-gas chromatography mass spectrometer (GCMS). OFP was calculated based on the Maximum Incremental Reactivity (MIR). Results from this study showed that the average total BTEX during the sampling period was 66.06 ± 2.39 μg/m³. Toluene (27.70 ± 0.97 μg/m³) was the highest, followed by m,p-xylene (13.87 ± 0.36 μg/m³), o-xylene (11.49 ± 0.39 μg/m³), ethylbenzene (8.46 ± 0.34 μg/m³) and benzene (3.86 ± 0.31 μg/m³). The ratio of toluene to benzene (T:B) is > 7, suggesting that VOCs in the Kuala Lumpur urban environment are influenced by vehicle emissions and other anthropogenic sources. The average of ozone formation potential (OFP) value from BTEX was 278.42 ± 74.64 μg/m³ with toluene and xylenes being the major contributors to OFP. This study also indicated that the average of benzene concentration in KL was slightly lower than the European Union (EU)-recommended health limit value for benzene of 5 μg/m³ annual exposure.

Temporal variations of ambient air pollutants and meteorological influences on their concentrations in Tehran during 2012-2017

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, 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 < 0.05) daily variations in which higher concentrations were observed on weekdays compared to weekend (holiday effect). Hourly O₃ 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 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.