Characteristics and health effects of formaldehyde and acetaldehyde in an urban area in Iran

Occupational exposure, carcinogenic and non-carcinogenic risk assessment of formaldehyde in the pathology labs of hospitals in Iran

Formaldehyde, a known carcinogenic compound, is commonly used in various medical settings. The objective of this study was to assess the carcinogenic and non-carcinogenic risks associated with occupational exposure to formaldehyde. This study was conducted in the pathology labs of four hospitals in Tehran. Cancer and non-cancer risks were evaluated using the quantitative risk assessment method proposed by the United States environmental protection agency (USEPA), along with its provided database known as the integrated risk information system (IRIS). Respiratory symptoms were assessed using the American thoracic society (ATS) questionnaire. The results indicated that 91.23% of exposure levels in occupational groups exceed the NIOSH standard of 0.016 ppm. Regarding carcinogenic risk, 41.03% of all the studied subjects were in the definite carcinogenic risk range (LCR > 10-4), 23.08% were in the possible carcinogenic risk range (10-5 < LCR < 10-4), and 35.90% were in the negligible risk range (LCR < 10-6). The highest index of occupational carcinogenesis was observed in the group of lab technicians with a risk number of 3.7 × 10-4, followed by pathologists with a risk number of 1.7 × 10-4. Furthermore, 23.08% of the studied subjects were within the permitted health risk range (HQ < 1.0), while 76.92% were within the unhealthy risk range (HQ > 1.0). Overall, the findings revealed significantly higher carcinogenic and non-carcinogenic risks among lab technicians and pathologists. Therefore, it is imperative to implement control measures across various hospital departments to mitigate occupational formaldehyde exposure levels proactively. These findings can be valuable for policymakers in the health sector, aiding in the elimination or reduction of airborne formaldehyde exposure in work environments.

Genome analysis of a newly isolated Bacillus velezensis-YW01 for biodegrading acetaldehyde

Acetaldehyde (AL), a primary carcinogen, not only pollutes the environment, but also endangers human health after drinking alcohol. Here a promising bacterial strain was successfully isolated from a white wine cellar pool in the province of Shandong, China, and identified as Bacillus velezensis-YW01 with 16 S rDNA sequence. Using AL as sole carbon source, initial AL of 1 g/L could be completely biodegraded by YW01 within 84 h and the cell-free extracts of YW01 has also been detected to biodegrade the AL, which indicate that YW01 is a high-potential strain for the biodegradation of AL. The optimal culture conditions and the biodegradation of AL of YW01 are at pH 7.0 and 38 °C, respectively. To further analyze the biodegradation mechanism of AL, the whole genome of YW01 was sequenced. Genes ORF1040, ORF1814 and ORF0127 were revealed in KEGG, which encode for acetaldehyde dehydrogenase. Furthermore, ORF0881 and ORF052 encode for ethanol dehydrogenase. This work provides valuable information for exploring metabolic pathway of converting ethanol to AL and subsequently converting AL to carboxylic acid compounds, which opened up potential pathways for the development of microbial catalyst against AL.

Research on the elimination of low-concentration formaldehyde by Ag loaded onto Mn/CeO2 catalyst at room temperature

Formaldehyde (HCHO) is one of the major air pollutants, and its effective removal at room temperature has proven to be a great challenge. In this study, an Ag/Mn/CeO2 catalyst for the catalytic oxidation of low-concentration HCHO at room temperature was prepared by a hydrothermal-calcination method. The removal performance of the Ag/Mn/CeO2 catalyst for HCHO was systematically studied, and its surface chemical properties and microstructure were analyzed. The incorporation of Ag did not change the mesoporous structure of the Mn/CeO2 catalyst but reduced the pore size and specific surface area. The Ag species included metallic Ag as the main component and part of Ag+. The well-dispersed Ag species on the catalyst provided sufficient active sites for the catalytic oxidation of HCHO. The more the Ag active sites, the more the lattice defects and oxygen vacancies generated from the interaction of Ag with Mn/CeO2. Precisely because of this, the Ag/Mn/CeO2 catalyst exhibited high catalytic activity for HCHO at room temperature with a removal efficiency of 96.76% within 22 h, which is 22.91% higher than that of the Mn/CeO2 catalyst. Moreover, the Ag/Mn/CeO2 catalyst showed good cycling stability and the removal efficiency reached 85.77% after five cycles. Therefore, the as-prepared catalyst is an effective and sustainable material that can be used to remove HCHO from actual indoor polluted air. This paper provides ideas for the research and development of efficient catalysts.

Inhalational exposure to formaldehyde, carcinogenic, and non-carcinogenic risk assessment: A systematic review

Formaldehyde is one of the most widely used substances in a variety of industries, although it was classified as a human carcinogen by the International Agency for Research on Cancer (IARC). The present systematic review was conducted to retrieve studies related to occupational exposure to formaldehyde until November 2, 2022. Aims of the study were to identify workplaces exposed to formaldehyde, to investigate the formaldehyde concentrations in various occupations and to evaluate carcinogenic and non-carcinogenic risks caused by respiratory exposure to this chemical among workers. A systematic search was done in Scopus, PubMed and Web of Science databases to find the studies done in this field. In this review, studies that did not meet the criteria specified by Population, Exposure, Comparator, and Outcomes (PECO) approach were excluded. In addition, the inclusion of studies dealing with the biological monitoring of FA in the body and review studies, conference articles, books, and letters to the editors were avoided. The quality of the selected studies was also evaluated using the Joanna Briggs Institute (JBI) checklist for analytic-cross-sectional studies. Finally, 828 studies were found, and after the investigations, 35 articles were included in this study. The results revealed that the highest formaldehyde concentrations were observed in waterpipe cafes (1,620,000 μg/m³) and anatomy and pathology laboratories (4237.5 μg/m³). Carcinogenic and non-carcinogenic risk indicated the potential health effects for employees due to respiratory exposure as acceptable levels of CR = 1.00 × 10^-4 and HQ = 1, respectively were reported to be exceeded in more than 71% and 28.57% of the investigated studies. Therefore, according to the confirmation of formaldehyde's adverse health effects, it is necessary to adopt targeted strategies to reduce or eliminate exposure to this compound from the occupational usage.

Toxicological Effects of Secondary Air Pollutants

Secondary air pollutants, originating from gaseous pollutants and primary particulate matter emitted by natural sources and human activities, undergo complex atmospheric chemical reactions and multiphase processes. Secondary gaseous pollutants represented by ozone and secondary particulate matter, including sulfates, nitrates, ammonium salts, and secondary organic aerosols, are formed in the atmosphere, affecting air quality and human health. This paper summarizes the formation pathways and mechanisms of important atmospheric secondary pollutants. Meanwhile, different secondary pollutants' toxicological effects and corresponding health risks are evaluated. Studies have shown that secondary pollutants are generally more toxic than primary ones. However, due to their diverse source and complex generation mechanism, the study of the toxicological effects of secondary pollutants is still in its early stages. Therefore, this paper first introduces the formation mechanism of secondary gaseous pollutants and focuses mainly on ozone's toxicological effects. In terms of particulate matter, secondary inorganic and organic particulate matters are summarized separately, then the contribution and toxicological effects of secondary components formed from primary carbonaceous aerosols are discussed. Finally, secondary pollutants generated in the indoor environment are briefly introduced. Overall, a comprehensive review of secondary air pollutants may shed light on the future toxicological and health effects research of secondary air pollutants.

Simultaneous influence of light and CO2 on phytoremediation performance and physiological response of plants to formaldehyde

Phytoremediation technology is an effective method to remove formaldehyde indoors, but the purification capacity and physiological response of plants to formaldehyde under the simultaneous influence of light and CO₂ have not been examined in previous studies. In this study, formaldehyde fumigation experiments were conducted on the C₃ plants Epipremnum aureum A. and Chlorophytum comosum L., and the crassulacean acid metabolism (CAM) plant Dieffenbachia maculate A. The phytoremediation performance and physiological response of plants were studied. The initial concentration of formaldehyde was established at 11.950 ± 1.442 [Formula: see text]; the light intensities were 448 ± 7 [Formula: see text], 1628 ± 22 [Formula: see text], and 3259 ± 22 [Formula: see text], respectively; and the concentrations of CO₂ were 455 ± 29 [Formula: see text], 978 ± 50 [Formula: see text], 2020 ± 66 [Formula: see text], and 3006 ± 95 [Formula: see text], respectively. The results indicated that the highest purification rates of formaldehyde by E. aureum, D. maculata, and C. comosum were 55.8%, 43.7%, and 53.2%, respectively. The light intensity had a positive effect on the formaldehyde purification rates of all three plants and positively stimulated peroxidase (POD) activity, while the CO₂ concentration had no significant impact on the formaldehyde purification capacity and plants' physiological characteristics. Exposure to formaldehyde inhibited formaldehyde dehydrogenase (FADH) activity and positively stimulated catalase (CAT) activity. The superoxide dismutase (SOD) activity positively correlated with the formaldehyde purification capacity of plants.

Respiratory functions and health risk assessment in inhalational exposure to vinyl acetate in the process of carpet manufacturing using Monte Carlo simulations

Vinyl acetate (VA) is a volatile compound and the main compound of the carpenter's glue. VA causes upper respiratory tract irritation, cough, and hoarseness in occupational exposure. As Iran is one of the biggest carpet producers in the world, this study was carried out to determine the inhalational health risk for employees exposed to VA. To the best of our knowledge, this was the first health risk assessment and the first evaluation of the lung functions and respiratory symptoms in employees exposed to VA. In the six finishing shops of carpet manufacturing industry in Kashan city, Iran the cross-sectional studies were conducted in 2022. The subjects comprised of forty male employees exposed to VA and of forty non-exposed employees in the reference group. VA analyses in the workers' breathing zones were performed based on the National Institute for Occupational Safety and Health (NIOSH) 1453 Method. VA concentrations were measured using Gas Chromatography-Mass Spectrometry (GC-MS). Inhalational risk assessment to VA was performed using the United States Environmental Protection Agency method and the Monte Carlo simulations. Respiratory functions were determined using the spirometry indices. In the exposed employees, considerably higher prevalence rates of pulmonary symptoms were observed in comparison with the control group. Statistical analysis showed a remarkable difference between lung function parameters measured in the case and the control groups. The VA Hazard Quotient (HQ) values for all working posts, except the quality control unit, were > 1 indicating the substantial inhalational non-cancerogenic risk. The sensitivity analysis revealed that the VA concentrations and exposure time had the most significant contribution in the uncertainty assessment. Therefore, it is recommended to decrease exposure to VA concentrations and to reduce the working time of exposed employees.

Health risk assessment of exposure to ambient formaldehyde in carpet manufacturing industries

Formaldehyde is categorized as a definitive carcinogen by the International Agency for Research on Cancer. To the best of our knowledge, no study has assessed the health risks of occupational exposure of workers in carpet manufacturing plants to formaldehyde. Therefore, this study assesses the health risks of the occupational exposure to formaldehyde of 67 male workers in carpet manufacturing plants in Iran in 2022. Exposure to formaldehyde was quantitatively determined after collecting personal exposure samples from the workers' respiratory zone and spectrophotometric analysis based on method number 3500 of the National Institute of Occupational Safety and Health. In the next step, the carcinogenic and noncarcinogenic risks based on personal exposure to formaldehyde were evaluated. Sensitivity analyses were employed using the Monte Carlo simulation method. The mean inhalation exposure of workers to formaldehyde was 0.636 mg m^-3. The inhalation cancer risk value based on the integrated risk information system for formaldehyde was 4.06×10^-4 ± 3.17×10^-5 (mean ± standard deviation), which exceeded the value reported by the US Environmental Protection Agency. An unacceptable carcinogenic risk level was found in 75.6% of workers. The highest mean inhalation cancer risk was 6.74×10^-4 (i.e., 6.74 additional cases per 10,000 employees exposed) was found in sizing post employees. The hazard quotient of formaldehyde was 0.311±0.024. The formaldehyde concentration had a considerable effect on the health risk. The findings of this study provide valuable scientific information that supports the development of future policies to enhance the health status of employees in carpet manufacturing plants.

Sorption of hazardous industrial organic liquids with environmentally friendly functionalized cellulosic sorbents

The performances of five cellulosic polymers with different functional groups (cellulose, cellulose acetate, cellulose phosphate, chitosan, and chitin) as sorbents of seven frequently used hazardous polar organic liquids (acrolein, butanone peroxide, epichlorohydrin, formaldehyde, furfuryl alcohol, propylene oxide, and vinyl acetate) are investigated in this study. Amongst the cellulosic sorbents, cellulose phosphate exhibited enhanced sorption properties (as high as 3.09–7.03 g/g) against all seven polar organic liquids investigated, and chitosan and chitin also demonstrated comparable sorption efficiencies (2.28–7.72 g/g and 2.55–5.86 g/g, respectively) to those of cellulose phosphate. According to our investigation, the enhanced sorption efficiency could be achieved due to low powder density of cellulose phosphate, which is caused by the weak intramolecular interaction amongst the polymer chains. In addition, cellulose phosphate, chitosan, and chitin also showed enhanced absorbed solvent recovery percents (71.4, 60.6, and 61.1%, respectively, in average) compared with that of pristine cellulose (43.8%). With excellent sorption efficiency, enhanced solvent recovery rate, and reusability after drying, these functionalized cellulosic sorbents can be excellent candidates to replace the conventional carbon and vermiculites-based sorbents, especially for liquid polar organic spill sorption.

Fossil-fuel and combustion-related air pollution and hypertension in the Sister Study

Hypertension is a leading risk factor for disease burden, with more than 200 million disability-adjusted life-years attributed to high blood pressure in 2015. While outdoor air pollution is associated with cardiovascular disease, the joint effect of exposure to air pollution from combustion products on hypertension has rarely been studied. We conducted a cross-sectional analysis to explore the association between combustion-related air pollution and hypertension. Census-tract levels of ambient concentrations of nine fossil-fuel and combustion-related air toxics (biphenyl, naphthalene, polycyclic organic matter, diesel emissions, 1,3-butadiene, acetaldehyde, benzene, acrolein, and formaldehyde) from the 2005 National Air Toxics Assessment database and NO2 from 2005 monitoring data were linked to baseline residential addresses of 47,467 women in the Sister Study cohort. Hypertension at enrollment (2003-2009) was defined as high systolic (≥140 mm Hg) or diastolic (≥90 mm Hg) blood pressure or taking antihypertensive medication. We used log-binomial regression and quantile-based g-computation to estimate the individual and joint effects of fossil-fuel and combustion-related air pollution on hypertension. Comparing the highest to lowest quartiles, diesel emissions (prevalence ratio (PR) = 1.05, 95% confidence interval (CI) = 1.01,1.08), 1,3-butadiene (PR = 1.04, 95%CI = 1.00,1.07), acetaldehyde (PR = 1.08, 95%CI = 1.04,1.12), benzene (PR = 1.05, 95%CI = 1.02,1.08), formaldehyde (PR = 1.08, 95%CI = 1.04,1.11), and NO2 (PR = 1.08, 95%CI = 1.05,1.12) were individually associated with higher prevalence of hypertension. The PR for the joint effect of increasing all ambient air toxics and NO2 by one quartile was 1.02 (95%CI = 1.01,1.04). Associations varied by race/ethnicity, with stronger associations observed among women reporting races/ethnicities (Hispanic/Latina, non-Hispanic Black and other) other than non-Hispanic White. In conclusion, we found that air pollution from fossil fuel and combustion may be a risk factor for hypertension.

Harnessing Waste Heat from Indoor lamps for Sustainable Thermocatalytic Mineralization of Acetaldehyde using Platinized TiO2

This study demonstrates the first reported thermocatalytic oxidation of an indoor volatile organic compound (VOC), acetaldehyde, by harnessing the waste-heat energy from indoor light sources (e.g., halogen lamps) without additional energy inputs. With an optimal Pt-TiO₂ catalyst, the designed catalyst-coated lampshade was successfully activated under waste-heat energy (∼120 °C) and achieved the complete mineralization of CH₃CHO into CO₂ (k = 0.02 min^-1). The catalytic activity of Pt-TiO₂ was extremely dependent on its preparation method which greatly influenced the characteristics (e.g., oxidation state and size) of Pt. The thermocatalytic oxidation mechanism of CH₃CHO over Pt-TiO₂ was investigated, which revealed that O₂ and H₂O sources play vital roles. Although Pt is an expensive noble metal, the thermocatalytic process on the Pt-TiO₂-coated lampshade without additional energy, along with its outstanding activity, can offset the high material cost. The proposed strategy offers a sustainable and feasible method for the degradation of indoor VOCs.

Characteristics and health effects of particulate matter emitted from a waste sorting plant

Solid waste components can be recycled in waste paper and cardboard sorting plants (WPCSP) through a multistep process. This work collected 15 samples every six days from each of the 9 points selected to study the processes taking place in a WPCSP (135 particulate matter samples total). Examining the concentration and size fraction of particulate matter (i.e., PM₁, PM_2.5 and PM₁₀) in WPCSP is an essential issue to notify policy makers about the health impacts on exposed workers. The major activities for increasing of the concentration of PM in various processing units in the WPCSP, especially in hand-picking routes I and II were related to manual dismantling, mechanical grinding, mechanical agitation, and separation and movement of waste. The results of this work showed that a negative correlation between temperature and particulate matter size followed the order PM₁₀ > PM_2.5 > PM₁. Exposure to PM_2.5 and PM₁₀ in the WPCSP lead to possible risk (HI = 5.561 and LTCRs = 3.41 × 10^-6 to 9.43 × 10^-5 for PM_2.5 and HI = 7.454 for PM₁₀). The exposure duration and the previous concentrations had the most effect on the ILCRs and HQs for PM_2.5 and PM₁₀ in all sampling sites. Hence, because WPCSP are infected indoor environments (I/O ratio > 1), the use of control methods such as isolation of units, misting systems, blower systems equipped with bag houses, protective equipment, a mechanical ventilation system, and additional natural ventilation can reduce the amount of suspended PM, enhance worker safety, and increase the recycling rate.

Ambient formaldehyde and mortality: A time series analysis in China

The potential health impact of low-level ambient formaldehyde has been historically overlooked. We conducted a two-stage time series analysis to investigate associations between ambient formaldehyde and daily nonaccidental, circulatory, and respiratory mortality and six subtypes based on 5,325,585 deaths in 275 Chinese counties between 2013 and 2018 and estimated a concentration-response curve to identify overall associations. After controlling for confounders from meteorological factors, air pollutants, time trend, and day of the week effect, with a 1-part per billion (ppb) increase in the daily concentration of formaldehyde on lag0 day, we found that mortality risks in nonaccidental, circulatory, and respiratory diseases increased by 0.36%, 0.36% and 0.41%, respectively. The curve indicated a possible threshold concentration at approximately 5 ppb for significant impact on nonaccidental and circulatory diseases. We suggest that ambient formaldehyde may represent a potential threat to public health and needs further investigation to support timely pollution regulation and health protection.

Atmospheric Carbonyl Compounds in the Central Taklimakan Desert in Summertime: Ambient Levels, Composition and Sources

Although carbonyl compounds are a key species with atmospheric oxidation capacity, their concentrations and sources have not been sufficiently characterized in various atmospheres, especially in desert areas. In this study, atmospheric carbonyl compounds were measured from 16 May to 15 June 2018 in Tazhong in the central Taklimakan Desert, Xinjiang Uygur Autonomous Region, China. Concentrations, chemical compositions, and sources of carbonyl compounds were investigated and compared with those of different environments worldwide. The average concentration of total carbonyls during the sampling period was 11.79 ± 4.03 ppbv. Formaldehyde, acetaldehyde, and acetone were the most abundant carbonyls, with average concentrations of 6.08 ± 2.37, 1.68 ± 0.78, and 2.52 ± 0.68 ppbv, respectively. Strong correlations between formaldehyde and other carbonyls were found, indicating same or similar sources and sinks. A hybrid single-particle Lagrangian integrated trajectory was used to analyze 72 h back trajectories. The values of C1/C2 (formaldehyde to acetaldehyde, 3.22–4.59) and C2/C3 (acetaldehyde to propionaldehyde, 15.00–17.03) from different directions and distances of the trajectories were consistent with the characteristics of a remote area. Relative to various environments, the carbonyl concentration in the Tazhong desert site was lower than that in urban areas and higher than that in suburban and remote areas, implying contributions from local primary and secondary sources. The obtained data can be used to improve the source and sink estimation of carbonyls at the regional scale.

Cannabis Cultivation Facilities: A Review of Their Air Quality Impacts from the Occupational to Community Scale

This review addresses knowledge gaps in cannabis cultivation facility (CCF) air emissions by synthesizing the peer-reviewed and gray literature. Focus areas include compounds emitted, air quality indoors and outdoors, odor assessment, and the potential health effects of emitted compounds. Studies suggest that β-myrcene is a tracer candidate for CCF biogenic volatile organic compounds (BVOCs). Furthermore, β-myrcene, d-limonene, terpinolene, and α-pinene are often reported in air samples collected in and around CCF facilities. The BVOC emission strength per dry weight of plant is higher than most conventional agriculture crops. Nevertheless, reported total CCF BVOC emissions are lower compared with VOCs from other industries. Common descriptors of odors coming from CCFs include "skunky", "herbal", and "pungent". However, there are few peer-reviewed studies addressing the odor impacts of CCFs outdoors. Atmospheric modeling has been limited to back trajectory models of tracers and ozone impact assessment. Health effects of CCFs are mostly related to odor annoyance or occupational hazards. We identify 16 opportunities for future studies, including an emissions database by strain and stage of life (growing cycle) and odor-related setback guidelines. Exploration and implementation of key suggestions presented in this work may help regulators and the industry reduce the environmental footprint of CCF facilities.

One-Pot Method to Synthesize Silver Nanoparticle-Modified Bamboo-Based Carbon Aerogels for Formaldehyde Removal

The present study demonstrated a freeze-drying-carbonization method to synthesize silver nanoparticle-modified bamboo-based carbon aerogels to remove formaldehyde. The bamboo-based carbon aerogel (BCA) has the advantages of controllable pore size and rich oxygen-containing groups, which can provide a good foundation for surface modification. BCA can greatly enhance the purification of formaldehyde by loading silver nanoparticles. The maximum adsorption capacity of 5% Ag/BCA for formaldehyde reached 42 mg/g under 25 ppm formaldehyde concentration, which is 5.25 times more than that of BCA. The relevant data were fitted by the Langmuir model and the pseudo 2nd-order model and good results were obtained, indicating that chemical absorption occurred between the carbonyl of formaldehyde and the hydroxyl of BCA. Therefore, silver nanoparticle-modified bamboo-based carbon aerogels play a positive role in the selective removal of formaldehyde. Silver nanoparticles promoted the activation of oxygen and strengthened the effect of BCA on HCHO adsorption.

Quantitative and Semiquantitative Health Risk Assessment of Occupational Exposure to Styrene in a Petrochemical Industry

Background

Styrene is one of the aromatic compounds used in acetonitrile-butadiene-styrene (ABS) producing petrochemicals, which has an impact on health of workers. Therefore, this study aimed to investigate the health risks of styrene emitted from the petrochemical industry in Iran.

Methods

Air samples were collected based on NIOSH 1501 method. The samples were analyzed by the Varian-cp3800 gas chromatograph. Finally, risk levels of styrene's health effects on employees were assessed by the quantitative method of the U.S. Environmental Protection Agency (U.S. EPA) and the semiquantitative way by the Singapore Occupational Safety and Health Association.

Results

Based on the results, the employees had the highest average exposure to styrene vapors (4.06 × 10 - 1 m g . ( k g - d a y ) - 1 ) in the polybutadiene latex (PBL) unit. Therefore, the most top predictors of cancer and non-cancer risk were 2.3 × 10 - 4 and 7.26 × 10 - 1 , respectively. Given that the lowest average exposure (1.5 × 10 - 2 m g . ( k g - d a y ) - 1 ) was in the dryer unit, the prediction showed a moderate risk of cancer (0.8 × 10 - 6 ) and non-cancer (2.3 × 10 - 3 ) for the employees. The EPA method also predicted that there would be a definite cancer risk in 16% and a probable risk in 76% of exposures. However, according to the semiquantitative approach, the rate of risk was at the "low" level for all staff. The results showed that there was a significant difference (p < 0.05) between the units in exposure and health risk of styrene (p < 0.05).

Conclusion

Given the high risk of styrene's health effects, appropriate control measures are required to reduce the exposure level.

Characterization and exposure assessment to urban air toxics across Middle Eastern and North African countries: a review

Middle East and North African (MENA) countries over the decades are experiencing rapid industrial and infrastructural growth combined with being the global hub of oil and gas industries. These economic transformations are associated with release of air pollutants including urban air toxics (UAT) through industrial, traffic, and constructional activities into ambient urban environments. UAT concentrations levels may exacerbate in most MENA countries considering high number of vehicular traffic populations and petrochemical industries which are one of the main sources of this pollutant. Therefore, the main objective of the study is to review major findings of UAT levels in urban areas across thirteen (13) MENA countries. The study characterizes various measured UAT, assesses their concentrations in ambient environment, and identifies their major sources of emissions by reviewing more than 100 relevant UAT papers across the selected MENA countries. It was found that benzene, heavy metals, formaldehyde, and dioxin-like compounds are the most reported UAT. The study concluded that road traffic, fuel stations, and petrochemical industries were identified as the main sources of ambient UAT levels. It was further reported that most of the studies were based on short-term ambient environment with limited studies in indoor environments. Therefore, it is highly recommended that future research should focus on innovative health impact assessment and epidemiological studies from exposure to UAT levels. Also embarking on sustainable mitigation approaches through urban greenery, eco-industrial estates infrastructural developments, and renewable energy shares will reduce UAT levels and improve human health.

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.

Experimental study of butane adsorption on coconut based activated carbon for different gas concentrations, temperatures and relative humidities

In this paper, the adsorption behaviour of activated carbon was investigated experimentally for changing butane concentration, temperature and relative humidity. Throughout the study, the coconut-based activated carbon was used. During the tests applied for butane concentration of 2, 4, 8, 20, 40 and 80 ppm, the temperature was taken as 15, 23 and 33°C for a relative humidity of 50, 70 and 90%. The results showed that butane concentration had a direct relationship with adsorption. However, temperature and adsorption were inversely proportional. As a result of the adsorption between activated carbon and butane, it led to physical adsorption as one of the most important types of adsorption due to Van der Waals forces among molecules. To create physical adsorption, lower temperature ranges were more convenient. The relative humidity of the air reduced the time to reach the maximum saturation rate. The increased relative humidity also reduced the amount of butane adsorbed. Also, 50% relative humidity range was an important turning point. Relative humidity affected the adsorption of butane at a relative humidity of 50%. However, the relative humidity at 70 and 90% significantly reduced butane adsorption; on the other hand, it considerably increased the adsorption of moisture.

Volatile Organic Compounds in Underground Shopping Districts in Korea

Underground shopping districts (USDs) are susceptible to severe indoor air pollution, which can adversely impact human health. We measured 24 volatile organic compounds (VOCs) in 13 USDs throughout South Korea from July to October 2017, and the human risk of inhaling hazardous substances was evaluated. The sum of the concentrations of the 24 VOCs was much higher inside the USDs than in the open air. Based on factor analysis, six indoor air pollution sources were identified. Despite the expectation of a partial outdoor effect, the impacts of the indoor emissions were significant, resulting in an indoor/outdoor (I/O) ratio of 5.9 and indicating elevated indoor air pollution. However, the effects of indoor emissions decreased, and the contributions of the pollution sources reduced when the USD entrances were open and the stores were closed. Although benzene, formaldehyde, and acetaldehyde exhibited lower concentrations compared to previous studies, they still posed health risks in both indoor and outdoor settings. Particularly, while the indoor excess cancer risk (ECR) of formaldehyde was ~10 times higher than its outdoor ECR, benzene had a low I/O ratio (1.1) and a similar ECR value. Therefore, indoor VOC concentrations could be reduced by managing inputs of open air into USDs.

Temporal and spatial discrepancies of VOCs in an industrial-dominant city in China during summertime

Ozone (O₃) pollution is currently problematic to cities across the globe. Many non-methane hydrocarbons (NMHCs) are efficient O₃ precursors. In this study, target volatile organic compounds (VOCs), including oxygenated VOCs (known as carbonyls), were monitored at eight sampling sites distributed in urban and suburban in the typical and industrial-dominant city of Shaoxing, Zhejiang province, China. At the suburban sites, C₈-C₁₂ alkanes, aromatics with lower reactivity (k_OH <13 × 10^-12 cm³ mol^-1 s^-1) and acetonitrile were more abundant than urban ones due to higher emissions from diesel-fueled trucks and biomass burning. In general, higher abundances of total quantified NMHCs (ΣNMHC) were found on high O₃ (HO) days. The increments of formaldehyde (C₁) and O₃ were higher in urban than suburban, while a reverse trend was seen for acetaldehyde (C₂). Substantial and local biogenic inputs of C₂ were found in suburban in the afternoon when both temperature and light intensity reached maximum of the day. In urban, higher increment was found for O₃ than the carbonyls, representing that the secondary formation of O₃ was more efficient. Distance decay gradient of most representative NMHCs were positively correlated to the distances from a westernmost industrial origin located at the upwind location. The net loss rates of the NMHCs ranged from -0.009 to -0.11 ppbv km^-1, while the higher rates were seen for the most reactive species like C₂-C₄ alkenes. The results and interpretation of this study are informative to establish efficient local control measures for O₃ and the related percussors for the microscale industrial cities in China.

Associations between observed formaldehyde concentrations and smoking, environmental tobacco smoke, and self-reported cancers and asthma: data for US children, adolescents, and adults

For the first time, the National Health and Nutrition Examination Survey (NHANES) released data on hemoglobin adducts of formaldehyde (HCHO) in public domain for US children aged 6-11 years, adolescents aged 12-19 years, and adults aged > = 20 years for 2015-2016. This study was undertaken to evaluate the associations between concentrations of HCHO in whole blood and smoking, exposure to environmental tobacco smoke (ETS), and self-reported diagnoses of cancers and asthma. Adult smokers were found to have higher adjusted concentrations of HCHO than nonsmokers (127.7 vs. 125.1 pmol/g Hb, p = 0.02). Exposure to ETS was not found to affect the adjusted concentrations of HCHO. No associations were observed between HCHO concentrations and self-reported diagnosis of "ever" cancer as well as self-reported presence of asthma at the time of participation in NHANES. HCHO concentrations were not found to differ across genders and racial/ethnic groups for children and adolescents. Among adults, non-Hispanic blacks (120.0 pmol/g Hb) had lower adjusted concentrations (p < = 0.01) of HCHO than non-Hispanic whites (128.8 pmol/g Hb), Mexican Americans (129.4 pmol/g Hb), other Hispanics (130.3 pmol/g Hb), and non-Hispanic Asians (127.9 pmol/g Hb). In conclusion, self-reported diagnoses of cancer and asthma were not found to be associated with observed concentrations of HCHO in whole blood.

Volatile Organic Compounds (VOCs) Removal from Indoor Air by Heterostructures/Composites/Doped Photocatalysts: A Mini-Review

The impact of volatile organic compounds (VOCs) on indoor air quality and, furthermore, on human health is still a subject of research investigations considering the large increase in forms of cancer and related diseases. VOCs can be 10 times higher in indoor air concentrations then that of the outdoors, as a consequence of emissions from electronics, building materials and consumer goods. Direct transformation of VOCs in mineralization products seems to be an alternative to reduce indoor air contaminants. The advantage of photocatalysis implementation in indoor air treatment is given by the absence of additional chemicals (such as H2O2) and waste. The present mini-review presents a comparative study on VOCs photocatalytic removal considering the photocatalyst composition, morphology and specific surface. The sheet-like morphology seems to provide a higher number of active sites which may contribute to oxidative reactions. The insertion of materials able to increase light absorbance or to mediate the charge carrier's transport will have a beneficial impact on the overall photocatalytic efficiency. Additionally, surface chemistry must be considered when developing photocatalysts for certain gas pollutants in order to favor molecule absorbance in the interfacial region. An energy consumption perspective is given based on the light intensity and irradiation period.

Fine Particulate Matter and Gaseous Compounds in Kitchens and Outdoor Air of Different Dwellings

Passive diffusion tubes for volatile organic compounds (VOCs) and carbonyls and low volume particulate matter (PM_2.5) samplers were used simultaneously in kitchens and outdoor air of four dwellings. PM_2.5 filters were analysed for their carbonaceous content (organic and elemental carbon, OC and EC) by a thermo-optical technique and for polycyclic aromatic hydrocarbon (PAHs) and plasticisers by GC-MS. The morphology and chemical composition of selected PM_2.5 samples were characterised by SEM-EDS. The mean indoor PM_2.5 concentrations ranged from 14 µg m⁻³ to 30 µg m⁻³, while the outdoor levels varied from 18 µg m⁻³ to 30 µg m⁻³. Total carbon represented up to 40% of the PM_2.5 mass. In general, the indoor OC/EC ratios were higher than the outdoor values. Indoor-to-outdoor ratios higher than 1 were observed for VOCs, carbonyls and plasticisers. PAH levels were much higher in the outdoor air. The particulate material was mainly composed of soot aggregates, fly ashes and mineral particles. The hazard quotients associated with VOC inhalation suggested a low probability of non-cancer effects, while the cancer risk was found to be low, but not negligible. Residential exposure to PAHs was dominated by benzo[a]pyrene and has shown to pose an insignificant cancer risk.

Utilization of metal-organic frameworks for the adsorptive removal of an aliphatic aldehyde mixture in the gas phase

Considerable efforts have been undertaken in the domain of air quality management for the removal of hazardous volatile organic compounds, particularly carbonyl compounds (CCs). In this study, the competitive sorptive removal of six CCs (namely, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde) was assessed using selected metal-organic frameworks (MOFs: MOF-5, MOF-199, UiO-66, and UiO-66-NH₂) and inexpensive commercial activated carbon as a reference sorbent. The sorption experiments were conducted using a mixture of the six CCs (formaldehyde and acetaldehyde at ∼1 Pa and propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde at ∼0.2 Pa) together with 15 Pa water and 2.6 Pa methanol in 1 bar nitrogen. For all of the carbonyl compounds other than formaldehyde, MOF-199 showed the best 10% breakthrough performance ranging from 34 L g^-1 and 0.14 mol kg^-1 Pa^-1 for acetaldehyde to 1870 L g^-1 and 7.6 mol kg^-1 Pa^-1 for isovaleraldehyde. Among all the sorbents tested, UiO-66-NH₂ exhibited the best 10% breakthrough performance metrics towards the lightest formaldehyde which remains to be one of the most difficult targets for sorptive removal (breakthrough volume: 285 L g^-1 and partition coefficient: 1.1 mol kg^-1 Pa^-1). Theoretical density functional theory (DFT)-based computations were also conducted to provide better insights into the adsorbate-adsorbent interactions. Accordingly, the magnitude of adsorption energy increased with an increase in the CC molar mass due to an enhancement in the synergetic interaction between C[double bond, length as m-dash]O groups (in adsorbate molecules) and the MOF active centers (open metallic centers and/or NH₂ functionality) as the adsorbent. Such interactions were observed to result in strong distortion of MOF structures. In contrast, weak van der Waals attraction between the hydrocarbon "tail" of CC molecules and MOF linkers were seen to play a stabilizing role for the sorbent structure. The presence of the NH₂ group in the MOF structure was suspected to play a key role in capturing lighter CCs, while such an effect was less prominent for heavier CCs. Overall, the results of this study provided a basis for the establishment of an effective strategy to enhance the sorption capacity of MOFs against diverse carbonyl species.

Prediction of Rate Coefficients for the H2CO + OH → HCO + H2O Reaction at Combustion, Atmospheric and Interstellar Medium Conditions

Despite the relevance of the H₂CO + OH → HCO + H₂O reaction for combustion, atmospheric, and interstellar medium conditions, a large discrepancy on energetic and kinetic data for this reaction is still observed in the previous literature. In this work, this hydrogen abstraction reaction has been investigated at the CCSD(T)/CBS level of theory, suggesting that both the prebarrier complex and saddle point are stabilized in relation to the reactants by 3.31 and 1.35 kcal mol^-1, respectively. Moreover, from the Gibbs free energy profile of the reaction coordinate, it has been verified that the formation of the prebarrier complex is endergonic, for temperatures above 550 K. Hence, for temperatures lower than 550 K, the reaction is described by a mechanism consisting of three elementary steps, while for higher temperatures it can be assumed to be an elementary reaction. Finally, the prediction of rate coefficients suggests that unified statistical rate theory best applies to the low temperature regime, while canonical variational rate coefficients better fit experimental data at the high temperature regime.

Dataset on specifications, carcinogenic and non-carcinogenic risk of volatile organic compounds during recycling paper and cardboard

Emissions of volatile organic compounds (VOCs) were studied during paper and cardboard recycling from a paper and cardboard solid waste recycling factory (PCSWRF). Data are summarized in this article for the following quantities for a PCSWRF during the winter in Tehran, Iran: VOC concentrations (μg m^-3), the percentage of detected VOCs, exposure indices (E_i) of individual and total VOCs (TVOCs), inhalation lifetime cancer risk (LTCR) of VOCs, the hazard quotient (HQ) of VOCs, sensitivity analysis (SA) for VOC exposure in different age groups (birth to <81), and Spearman's rank correlation coefficients (r) between VOC concentrations and meteorological parameters. For more insight please see "Characteristics and Health Effects of Volatile Organic Compound Emissions during Paper and Cardboard Recycling"[1], https://doi.org/10.1016/j.scs.2019.102005.

Diurnal patterns of N-nitrosodimethylamine and formaldehyde behaviors in different seasons in surface water influenced by effluent from sewage treatment plants

N-nitrosodimethylamine (NDMA) and formaldehyde (FAH) are probable carcinogenic disinfection by-products and have been found to occur in areas of the Yodo River basin that are influenced by treated wastewater. The diurnal patterns of them were examined with water samples collected over 4 years in different seasons at five outlets of four sewage treatment plants (STPs), seven main stream sites, and five tributary sites in the basin. Based on mass flux calculations, STPs were shown to be the main sources of the downstream for NDMA and FAH loads in the study area. Moreover, results revealed that photo degradable NDMA and non-photo degradable FAH showed different fates during the river transportation. For NDMA, in addition to direct photolysis, water temperature was identified as an important factor in NDMA attenuation in surface waters. NDMA attenuated significantly in the daytime and even during summer nights but persisted during winter nights, while attenuation of FAH was found to mainly be influenced by water temperature, and persisted during winter. Their behaviors were compared in an artificial river channel and whole study area, clearly demonstrating the importance of monitoring them in the water environment during periods of low UV intensity and water temperature, especially winter nights.

Nanostructured Semiconducting Metal Oxide Gas Sensors for Acetaldehyde Detection

Volatile organic compounds (VOCs) are among the most abundant air pollutants. Their high concentrations can adversely affect the human body, and therefore, early detection of VOCs is of outmost importance. Among the different VOCs, in this review paper we have focused our attention to the monitoring of acetaldehyde by chemiresistive gas sensors fabricated from nanostructured semiconducting metal oxides. These sensors can not only provide a high sensing signal for detection of acetaldehyde but also high thermal and mechanical stability along with a low price. This review paper is divided into three major sections. First, we will introduce acetaldehyde as an important VOC and the importance of its detection. Then, the fundamentals of chemiresistive gas sensors will be briefly presented, and in the last section, a survey of the literature on acetaldehyde gas sensors will be presented. The working mechanism of acetaldehyde sensors, their structures, and configurations are reviewed. Finally, the future development outlook and potential applications are discussed, giving a complete panoramic view for researchers working and interested in acetaldehyde detection for different purposes in many fundamental and applicative fields.

Comparative health risk assessment of in-vehicle exposure to formaldehyde and acetaldehyde for taxi drivers and passengers: Effects of zone, fuel, refueling, vehicle's age and model

This study aimed to assess the carcinogenic and non-carcinogenic risks of in-vehicle exposure in Tehran, Iran to formaldehyde and acetaldehyde for different models of taxis, and to explore the effects of city zone, taxi vehicle type, the taxi's age (<1, 1-5, 5-10), fuel type (gasoline, CNG, and LPG), and refueling activities on the estimated health risks based on previously measured concentrations. The overall and age-specific carcinogenic and non-carcinogenic risks of these compounds for taxi drivers and passengers were estimated separately using Monte Carlo simulations. Three scenarios of exposure frequency were defined for taxis commuting in different zones of city: Restricted Traffic Zone (RTZ) and Odd-Even Zone (OEZ) as two plans to reduce air pollution, and no-restriction zone (NRZ). The carcinogenic risks for drivers and passengers, the average risks of formaldehyde and acetaldehyde for most cases were above the 1 × 10^-4. The health risks were greater in Restricted Traffic Zone (RTZ) and Odd-Even Zone (OEZ) in comparison to no-restriction zone (NRZ). The carcinogenic risk from formaldehyde exposures were higher than those for acetaldehyde in all cases. Taxis fueled with LPG showed lower cancer risks for both acetaldehyde and formaldehyde. Refueling increased the carcinogenic risk from both compounds. For non-carcinogenic risks from acetaldehyde, the average hazard ratios for both drivers and passengers were >1, indicating a non-negligible risk. Cancer and non-cancer risks for the taxi drivers were greater than the passengers given the higher time of occupancy. The present study showed that transportation in taxis can impose significant long-term health risks to both passengers and drivers. Development and investment in cleaner choices for public transportations are required.

Adsorption properties of advanced functional materials against gaseous formaldehyde

Intense efforts have been made to eliminate toxic volatile organic compounds (VOCs) in indoor environments, especially formaldehyde (FA). In this study, the removal performances of gaseous FA using two metal-organic frameworks, MOF-5 and UiO-66-NH₂, and two covalent-organic polymers, CBAP-1 (EDA) and CBAP-1 (DETA), along with activated carbon as a conventional reference material, were evaluated. To assess the removal capacity of FA under near-ambient conditions, a series of adsorption experiments were conducted at its concentrations/partial pressures of both low (0.1-0.5 ppm/0.01-0.05 Pa) and high ranges (5-25 ppm/0.5-2.5 Pa). Among all tested materials at the high-pressure region ㅐ (e.g., at 2.5 ppm FA), a maximum adsorption capacity of 69.7 mg g^-1 was recorded by UiO-66-NH₂. Moreover, UiO-66-NH₂ also displayed the best 10% breakthrough volume (BTV10) of 534 L g^-1 (0.5 ppm FA) to 2963 L g^-1 (0.1 ppm FA). In contrast, at the high concentration test (at 5, 10, and 25 ppm FA), the maximum BTV10 values were observed as: 137 (UiO-66-NH₂), 144 (CBAP-1 (DETA)), and 36.8 L g^-1 (CBAP-1 (EDA)), respectively. The Langmuir isotherm model was observed to be a better fit of the adsorption data than the Freundlich model under most of the tested conditions. The superiority of UiO-66-NH₂ was attributed to the van der Waals interactions between the linkers (framework) and the hydrocarbon "tail" (FA) coupled with interactions between its open metal sites and the FA carbonyl groups. This study demonstrated the good potential of these advanced functional materials toward the practical removal of gaseous FA in indoor environments.

Seasonal and diurnal characteristics of carbonyls in the urban atmosphere of Changsha, a mountainous city in south-central China

Seasonal and diurnal variations of carbonyl compounds were investigated in the ambient air of a mountainous city in China, from September 2014 to July 2015. The most abundant carbonyl compounds are formaldehyde, acetaldehyde and acetone, propionaldehyde and methacryladehyde (MACR), which were all measured in most samples. The average concentrations of formaldehyde, acetaldehyde, acetone, propionaldehyde and MACR in the atmosphere in Changsha were broken down into each season: 6.57, 3.29, 3.66, 0.67 and 0.54 μg/m³ respectively during Spring, 14.09, 8.28, 9.02, 1.28 and 0.6 μg/m³, respectively during Summer, 9.24, 5.48, 8.62, 0.73 and 0.62 μg/m³, respectively during Autumn, and 5.88, 4.84, 7.84, 0.87 and 0.26 μg/m³ respectively during Winter. And majority of the species had higher concentration during noon, showing photochemical oxidation and human activities played an important role in diurnal variation. The highest average C1/C2 (formaldehyde/acetaldehyde) ratio was observed in summer (2.10) compared to those (1.33-2.03) in other seasons, implying the photochemical activities had a positive effect on increasing the ratio of C1/C2. In this study, the monthly concentration of formaldehyde produced from isoprene accounts for 4.8%-39.1% of formaldehyde in ambient air. Strong correlation among some carbonyl compounds means that they came from the same sources. Photochemical reaction was the main source of carbonyl compounds in summer and vehicular exhaust (gasoline and diesel engines) in winter. Changsha is not a completely urbanized city and it is rich in vegetation of broadleaf evergreen shrubs. Both atmospheric photochemical reactions and anthropogenic sources, including vehicular exhaust and industrial processes, dominate the levels of carbonyls. The ILTCR and HQ values of formaldehyde and acetaldehyde are 1.23E-04 and 1.34E-05, 2.80E-01 and 1.86E-01, respectively.

Concentrations and health effects of short- and long-term exposure to PM2.5, NO2, and O3 in ambient air of Ahvaz city, Iran (2014-2017)

The primary objective of the present study was to evaluate the concentrations and short and long-term excess mortality attributed to PM_2.5, NO₂, and O₃ observed in ambient air of Ahvaz during March 2014 to March 2017 period using the AirQ + software developed by the World Health Organization (WHO), which is updated in 2016 by WHO European Centre for Environment and Health. The hourly concentrations of PM_2.5, O₃, and NO₂ measured at different regulatory monitoring network stations in Ahvaz city were obtained from the Department of Environment (DOE) of the city. Then, for various air quality monitoring stations, the 24-h average concentration of PM_2.5, 1-h average of NO₂ concentration, and maximum daily 8-h O₃ concentrations were calculated using Excel 2010 software. When the maximum daily 8-h ozone means exceeding the value of 35, it was subtracted from 35 to calculate SOMO35 indicator for modeling. Validation of air quality data was performed according to the Aphekom and WHO's methodologies for health impact assessment of air pollution. Year-specific city population and baseline incidence of the health outcomes were obtained. The three-year averages of PM_2.5, NO₂, and O₃ concentrations were 68.95 (±39.86) μg/m³, 135.90 (±47.82) μg/m³, and 38.63 (±12.83) parts-per-billion-volume (ppbv), respectively. SOMO35 values of ozone were 6596.66, 3411.78, and 470.88 ppbv in 2014-2015, 2015-2016, and 2016-2017 years, respectively. The AP and number of natural deaths due to NO₂ were higher than PM_2.5 except the last year (2016-2017), causing about 39.18%, 40.73%, and 14.39% of deaths within the first, the second, and the third year, respectively. However, for the last year, the natural mortality for PM_2.5 was higher than NO₂ (34.46% versus 14.39%). The total number of natural mortality caused by PM_2.5 and NO₂ in all years was 4061 and 4391, respectively. A significant number of deaths was estimated to be attributed to the given air pollutants. It can be concluded that by designing and implementing air pollution control strategies and actions, both health effects and economic losses will be prevented.

Indoor air quality in waterpipe cafés: exposure level to particulate matter

Waterpipe is increasingly being used worldwide. Despite waterpipe cafés gaining popularity among Iranian population, there is a paucity of research measuring exposures and assessing the health effects of waterpipe smoke in these places. The objective of the current study was to investigate the exposure to PM10, PM2.5, and PM1 concentrations and risk assessment of PM2.5 exposures in different age groups in the indoor air of waterpipe cafés. The study samples were taken from indoor air of 50 waterpipe cafés in Ardabil, Iran. The PM10, PM2.5, and PM1 concentrations were assessed using a portable GRIMM dust monitors. The mean (±SD) concentrations of indoor air PM10, PM2.5, and PM1 were 765 ± 352, 624 ± 327, and 500 ± 305 μg/m3, respectively. The mean of HQ (hazard quotient) for PM2.5 in all age groups of 16 and older was > 1, which corresponds to an unacceptably high risk for human health. Also, the mean of ELCRs (excess lifetime cancer risk) for PM2.5 in different age groups exceeded the limit value by the USEPA. The results indicated that the PM concentration is significantly influenced by the number of waterpipe smokers, type of ventilation system, and kind of tobacco. Therefore, waterpipe cafés are a potential source for exposure to PM10, PM2.5, and PM1 and increase the risk of respiratory diseases and cardiovascular problems among waterpipe smokers.

A case study of BTEX characteristics and health effects by major point sources of pollution during winter in Iran

This study characterized spatio-temporal variations in the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in the vicinity of gas and compressed natural gas (CNG) stations in Tehran, Iran. Health risk assessment (HRA) was computed using Monte Carlo simulations (MCS) for evaluating inhalation lifetime cancer risk (LTCR), the hazard quotient (HQ), and sensitivity analysis (SA) for BTEX exposure in different age groups (birth to <81) and as a function of distance (0-250 m) from the center of the stations. For all monitoring stations, the average values of benzene, toluene, ethylbenzene, and xylene in winter were 466.09 ± 132.25, 873.13 ± 233.51, 493.05 ± 141.22, and 910.57 ± 145.40 μg m^-3, respectively. The mean wintertime ratios of T/B for the 12 stations ranged from 1.69 to 2.04. Furthermore, there was no significant relationship between the concentration of BTEX with either the specific month or distance from the center of stations (p > 0.05). Factors promoting BTEX formation in the study region were fuel evaporation and gas/CNG station emissions. The LTCRs for the target compounds in the winter for different age groups and distances from the center of stations was limited to 2.11 × 10^-4 to 1.82 × 10^-3 and 2.30 × 10^-4 to 2.01 × 10^-3, respectively, which exceeded proposed values by U.S. EPA. Moreover, the HQs for BTEX for three age groups and distances were limited to between 2.89 × 10^-5 and 9.33 × 10^-2, which were lower than the acceptable limit (HQs < 1). The results of this work are applicable to similar areas that are heavily populated with vehicular traffic. This study motivates a closer look at mitigation strategies to limit the health effects of carcinogenic emissions such as benzene and ethylbenzene from gas/CNG stations.

Concentration and type of bioaerosols before and after conventional disinfection and sterilization procedures inside hospital operating rooms

Operating rooms (ORs) in hospitals are sensitive wards because patients can get infections. This work aimed to characterize the type and concentration of bioaerosols in nine ORs of an educational hospital before and after sterilization and disinfection. During 2017, fungal samples were incubated at 25-28 °C for 3-7 days and bacterial samples at 37 °C for 24-48 h. The study results showed that the concentrations of fungi before cleaning procedures (for both of disinfection and sterilization) were limited from 4.83 to 18.40 CFU/m3 and after cleaning procedures ranged from 1.90 to 8.90 CFU/m3. In addition, the concentrations of bacteria before cleaning procedures were limited 14.65-167.40 CFU/m3 and after cleaning procedures ranged from 9.50 to 38.40 CFU/m3. The difference between the mean concentrations of airborne bioaerosols before and after sterilization was significantly different than the suggested value of 30 CFU/m3 (p ≤ 0.05). The bacterial concentration was higher than the recommended value (30 CFU/m3) in 41% of the ORs. The main fungal species identified in the indoor air of ORs (before vs. after sterilization) were A. fumigatus (25.6 vs. 18.3%), A. Niger (11.6 vs. 5.8%), Penicillium spp. (5.5 vs. 3.3%), Alternaria spp. (2.8 vs. 0.7%), Fusarium spp. (9.7 vs. 3.7%), Mucor spp. (15 vs. 12.7%), Cephalotrichum spp. (1.7 vs. 0.8%), A. Flavus (24.6 vs. 18.5%), Cladosporium spp. (2.6 vs. 0.8%), and Trichoderma spp. (0 vs. 0.9%). The growth of biological species even after sterilization and disinfection likely resulted from factors including poor ventilation, sweeping of OR floors, inadequate HVAC filtration, high humidity, and also lack of optimum management of infectious waste after surgery. Designing well-constructed ventilation and air-conditioning systems, replacing HEPA filters, implementing more stringent, frequent, and comprehensive disinfection procedures, and controlling temperature and humidity can help decrease bioaerosols in ORs.

On the chemical nature of precipitation in a populated Middle Eastern Region (Ahvaz, Iran) with diverse sources

This study reports on the chemical composition of rainwater collected at three ground sites with varying degrees of pollution in Ahvaz, Iran, between January 2014 and February 2015. A total of 24 rainwater samples were analyzed for pH and concentrations of trace elements (Fe, Al, Pb, and Cd) and major ions (Na⁺, NH₄⁺, Ca²⁺, Mg²⁺, HCO₃^-, NO₃^-, Cl^- and SO₄^2-). Principle Component Analysis (PCA) was used to identify sources of the measured species. The equivalent concentration of the components followed the order of Ca²⁺ > SO₄^2- > HCO₃^- > NH₄⁺ > Cl^- > Na⁺ > NO₃^- > Mg²⁺. The average pH of the rainwater samples was 6, and only three events exhibited acidic conditions below a pH of 5.6. The lowest and the highest average pH values were observed in the high traffic area (5.96) and industrial area (6.54), respectively. The highest and lowest Ca²⁺ levels were observed in the industrial and high traffic areas, respectively. Na⁺, Mg²⁺, and SO₄^2- exhibited their highest and lowest concentrations in the industrial and high traffic areas, respectively. 70.36% of the total variance was due to anthropogenic species (Ca²⁺, SO₄^2-, Mg²⁺, NO₃^-, Cl^-), soil particles (Cl^-, Na⁺, and HCO₃^-), and biomass burning (NH₄⁺, pH). The results of this study show that local anthropogenic sources and Middle Eastern Dust (MED) storms affect the rainwater chemistry strongly, which the latter stems from the Arabian Peninsula, Kuwait, Iraq, and some parts of Iran.

Seasonal Variation in Culturable Bioaerosols in a Wastewater Treatment Plant

Bioaerosols produced from Wastewater Treatment Plants (WWTPs) can pose health risks to plant workers and nearby inhabitants. There is a gap in air quality data for WWTPs in developing countries. The present study aimed to measure airborne bacterial and fungal concentrations in a WWTP in southwestern Iran between September 2015 and May 2016. Active sampling was conducted around operational units, and a total of 600 bacterial and fungal samples were collected. Spatial and seasonal comparisons were made. The highest average concentrations of culturable bacterial aerosol at seasonally dependent locations were, in decreasing order, 2581 ± 401 and 1952 ± 390 CFU m^-3 for the selector and aeration tanks, respectively, in autumn; 1363 ± 299 CFU m^-3 for the aeration tank in winter; and 1738 ± 350 CFU m^-3 for the screw pump in spring. Furthermore, the predominant genera of airborne fungi isolated from the air of the WWTP in all three seasons were Cephalotrichum spp., Alternaria spp., Penicillium spp., Monilia spp., and Aspergillus spp. The results of this work emphasize the necessity of controlling WWTP workers' exposure to bioaerosols when bacteria and fungi become aerosolized during aeration.