Influence of the seasonality and of urban variables in the BTEX and PM2.5 atmospheric levels and risks to human health in a tropical coastal city (Fortaleza, CE, Brazil)

Occurrence, migration and environmental effects of neglected BTEX in the coastal multiple environments

Benzene, toluene, ethylbenzene, and o-, m-, p-xylene (BTEX) are toxic and hazardous pollutants with critical impacts on ecosystem health and air quality. Here, the spatial distributions, interfacial exchange fluxes and environmental effects of BTEX were investigated in multiple environmental mediums in the East China Sea. The average concentrations of ∑BTEX in the surface (bottom) seawater, atmosphere and sediment were 235 ± 168 (152 ± 98.3) ng L-1, 600 ± 408 pptv and 0.76 ± 0.29 μg kg-1, respectively, generally decreasing from inshore to offshore regions. Furthermore, BTEX in seawater served as sources for those in atmosphere and sediment, with interfacial exchange fluxes of ∑BTEX estimated at 734 ± 748 and 1.80 ± 1.56 g km-2 d-1, respectively. Ocean currents, air masses properties and accumulation of long-term terrestrial inputs were identified as key factors controlling BTEX distributions across the different mediums. Additionally, the ozone and secondary organic aerosol formations potentials of atmospheric ∑BTEX were 0.134 ± 0.093 and 14.3 ± 11.5 μg m-3, respectively. This study addresses a critical gap in data on BTEX contaminations in coastal environments, improves understanding of their interfacial exchange processes, underscores the necessity of continuous monitoring and provided a valuable basis for environmental impact assessments.

Influence of source contributions and seasonal variations on particle-associated polycyclic aromatic hydrocarbons and cancer risks in a rapidly urbanizing South American City (Fortaleza, Brazil)

Particulate matter (PM) was recently classified as a Group 1 (carcinogen to humans), marking a significant step forward in prioritizing the monitoring of airborne particles in urban environments. In this sense, the primary objective was to evaluate the cancer risk associated with PM10 and polycyclic aromatic hydrocarbons (PAHs) levels, with a focus on the contribution of different source types and seasonal variations in a highly urbanized city located in the tropical semiarid region of South America, where air quality studies and understanding remain scarce. The PM was collected using a Hivol sampler, and the PAHs contained within were extracted using Soxhlet extraction and analyzed by gas chromatograph with mass spectrometery. The PM10 levels ranged from 8.9 to 33.3 µg/m³ and from 17.2 to 33.2 µg/m³, in the rainy and dry season, respectively, while the ΣPAHs ranged from 0.18 to 2.03 ng/m³ (wet season) and from 0.14 to 0.64 ng/m³ (dry season). The ratio of PM10 levels between wet and dry periods remained relatively stable throughout the year, consistently staying below 1 across most parts of the city. However, in areas with higher traffic flow, classified as moderate to deep urban canyon zones, levels were significantly higher during the dry period. The sources appointment indicates that the contribution of the vehicle fleet is geographically predominant, followed by contributions from the burning of coal and wood, and, more succinctly, the influence of the existing industrial sectors in the region. Compared to other urban and industrial regions worldwide, Fortaleza's risk levels are moderate to relatively low. However, the relative cancer risk is approximately 22% higher for smokers compared to nonsmokers.

Extensive investigation of seasonal and spatial fluctuations of BTEX in an industrial city with a health risk assessment

There are many pollutants in the air that can be harmful to human health. Their impact varies based on factors such as the kind of pollutant, duration of exposure, and concentration levels. Volatile organic compounds are particularly significant carcinogens among the various pollutants present in the air. Consequently, people who are exposed to these harmful airborne pollutants suffer permanent consequences. This study examines the properties of BTEX compounds-benzene, toluene, ethylbenzene, and xylene-as well as their sources and risk assessments throughout a one-year period from March 21, 2019, to March 20, 2020, in Karaj, Iran's largest industrialized city. First, utilizing a geographical information system that covered the entire city, 17 locations within Karaj were chosen for this purpose. Then, samplings were carried out in the spring, summer, autumn, and winter months with the NIOSH 1501 method. During the research period, 68 samples of BTEX compounds were collected. The adsorption of these contaminants on the activated carbon adsorbents was performed using an environmental sampling pump with a flow rate of 0.2 L/min for 1 h. The samples were subsequently prepared using a carbon disulfide solution and injected into a GC-FID for analysis. In this research, the average annual concentration of BTEX compounds in the air of Karaj city was obtained at 33.01 µg/m3. Autumn and spring had the highest and lowest average concentrations of BTEX compounds, respectively. In addition, sites 5 and 8 had the highest average annual concentrations of these pollutants. The sourcing conducted in this study showed that transportation and fuel consumption, as well as industries, were the primary sources of pollution in the city. In addition, the excess lifetime cancer risk was higher than the guideline value in some sites and lower in others. Furthermore, the Hazard Quotients were lower than 1, but in general, the citizens of Karaj were at serious risk from exposure to this group of pollutants.

Airborne particulate matter integral assessment in Magdalena department, Colombia: Patterns, health impact, and policy management

The relevance of atmospheric particulate matter (PM) to health and the environment is widely known. Long-term studies are necessary for understanding current and future trends in air quality management. This study aimed to assess the long-term PM concentration in the Magdalena department (Colombia). It focused on the following aspects: i) spatiotemporal patterns, ii) correlation with meteorology, iii) compliance with standards, iv) temporal trends over time, v) impact on health, and vi) impact of policy management. Fifteen stations from 2003 to 2021 were analyzed. Spearman-Rho and Mann-Kendall methods were used to correlate concentration with meteorology. The temporal and five-year moving trends were determined, and the trend magnitude was calculated using Teil-Sen. Acute respiratory infection odd ratios and risk of cancer associated with PM concentration were used to assess the impact on health. The study found that the maximum PM10 concentration was 194.5 μg/m3, and the minimum was 3 μg/m3. In all stations, a negative correlation was observed between PM10 and atmospheric water content, while the wind speed and temperature showed a positive correlation. The global trends indicated an increasing value, with five fluctuations in five-year moving trends, consistent with PM sources and socio-economic behavior. PM concentrations were found to comply with national standard; however, the results showed a potential impact on population health. The management regulation had a limited impact on increasing concentration. Considering that national regulations tend to converge towards WHO standards, the study area must create a management program to ensure compliance.

Evaluation of the ventilation and pollutant exposure risk level inside 3D street canyon with void deck under different wind directions

With continuous global warming, growing urban population density, and increasing compactness of urban buildings, VD (void deck) street design has become increasingly popular in city planning, especially in tropical countries. However, understanding on traffic pollutant dispersion inside the street canyons with VDs is still at early stage. This paper evaluates quantitatively the effects of VD location and wind direction on the ventilation and traffic pollutant exposure inside the street canyon with VDs. The results show that under seven wind directions (0°, 15°, 30°, 45°, 60°, 75°, and 90°), the VD provides higher ACH than that of the regular canyon, especially at high α (angle between the approaching wind and the canyon axis). Also, mean K (dimensionless pollutant concentration) values of the canyon wall and pedestrian respiration plane on one side where VD is located are significantly reduced compared to the regular canyon. Therefore, when VDs are at both buildings, both pedestrian respiration planes and walls have the lowest K values, thus providing the best living environment for pedestrians and near-road residents. In addition, as α increases, the K values on both respiration planes significantly decrease except for the leeward respiration plane of the canyon with the windward VD. These findings can help to design urban street canyons for mitigating traffic pollution risk and improving ventilation in tropical cities with frequently changing wind directions.

Temporal variability of PM2.5 and its possible sources at the tropical megacity, Bengaluru, India

The mass concentrations of PM_2.5 were measured at a tropical megacity, Bengaluru, India, for the year 2015. The mean mass concentrations showed large fluctuations on day to day basis with values less than the Indian National Ambient Air Quality Standard (INAAQS) of 60 µg m^-3. The observed annual mean mass concentration of 28 ± 11 µg m^-3 is also within the INAAQS value of 40 µg m^-3. The diurnal trend of PM_2.5 concentration showed bimodal distribution, with the primary peak in the morning and the secondary one during the late evening hours. The timing of the peaks matched with rush traffic hours. Strong seasonality is observed in the diurnal concentration of PM_2.5 with the highest value during winter (50 ± 22 µg m^-3) and the lowest of (11 ± 5 µg m^-3) in the monsoon. The weekend PM_2.5 mass concentrations were less than those on the weekdays up to a maximum of 100%. The decrease in PM_2.5 mass concentration was also observed on the day of the strike when many busses were off the road. Vehicular traffic is suggested as one of the primary contributors of PM_2.5 in this region. The health risk assessment in this study, points to ischemic heart disease as the primary cause of PM_2.5-induced death.

Effect-directed analysis of toxic organics in PM2.5 exposure to the cellular bioassays in vitro: Application in Shanxi of China

To optimize the effect-directed analysis (EDA) approach to identify the fine particulate matter (PM_2.5) bound organic toxicants, Jinzhong city, in the Shanxi Province of China, was selected as the object of our study. First, PM_2.5 samples were collected and their organic extracts were separated out in 9 fractions (F1-F9) using reversed-phase high performance liquid chromatography after purification using gel permeation chromatography. Second, the toxicity effects of each fraction were measured by human bronchial epithelial cells (BEAS-2B) in vitro. And toxicity effects included antioxidant stress (ROS, LDH, and CAT) and an inflammatory response (IL-6, IL-1β, and TNF-α). The results showed that the scores of the toxicity effects on multiple lines of evidence were the highest in the F3 and F4 fractions compared with those of the control. Subsequently, the main poisons, o-cymene, p-cymene, benzene, ethylbenzene, xylene, and styrene, were identified using GC×GC-TOF/MS. Finally, to confirm the above possible candidates, (1) the levels of o-cymene, p-cymene and BTEXS in daily PM_2.5 were measured using GC-MS in November 2020, and the rates of detection of these pollutants were 100% in PM_2.5. Among them, o-cymene and p-cymene were first reported as the key toxic substances of PM_2.5, and their average concentration values were 0.16 ± 0.11 and 0.18 ± 0.15 ng‧m^-3, respectively. (2) the toxicity of p-cymene may be no less than that of other benzene derivatives according to their LC50 in Daphnia magna. (3) based on canonical correlation analysis, the exposure to p-cymene, benzene, and styrene in PM_2.5 was most likely associated with the toxicity effects (CAT, IL-6, and TNF-α), which in turn caused the observed toxicity. In conclusion, p-cymene, benzene, and styrene were found to be the key toxic organics in PM_2.5 for cells in vitro. EDA technology avoids the limitations of chemical analysis and uncertainty of the biological testing and adds new toxicants to the control list of PM_2.5, contributing to this study field. However, the application of EDA to PM_2.5 still faces challenges such as the selection of biological effects, loss of toxicity with the separation process, influence of the dosing method, and identification of the unknown effects of pollutants.

Level of air BTEX in urban, rural and industrial regions of Bandar Abbas, Iran; indoor-outdoor relationships and probabilistic health risk assessment

This study focused on the measurement of BTEX (benzene, toluene, ethylbenzene and xylene) concentrations in the air of various regions and indoor-outdoor environments in Bandar Abbas, Iran. Air samples were taken actively and analyzed by gas chromatography-mass spectrometry (GC-MS) during two one-month periods i.e., Feb 2020 (period I) and Sep/Oct 2020 (period II). The mean air temperature and the levels of all BTEX compounds were higher in period II. The highest total BTEX (t-BTEX) levels (median [min-max]) were found in the urban region (18.00 [5.21-67.24] μg m^-3), followed by industrial region (7.00 [2.05-14.76] μg m^-3) and rural region (2.81 [ND-7.38] μg m^-3). The significant positive correlations between all BTEX compounds and T/B ratio >1 indicated the vehicular traffic as the main source of emission. At 95th percentile probability, the non-cancer risk of t-BTEX in urban region was only less than one order of magnitude below the threshold level of unity (1.91E-01) and the cancer risk of benzene exceeded the recommended level of 1.0E-06 by U.S. EPA in urban (7.69E-06) and industrial (2.97E-06) regions. It was found that the indoor/outdoor ratio of BTEX concentration in beauty salon and hospital was greater than 1. Overall, the current levels of BTEX in the ambient air of study area, especially near urban roadside and in some indoor environments, should not be overlooked and appropriate mitigation actions should be undertaken.