Air pollution, especially particulate matter (PM), is a significant environmental pollution worldwide. Studying the chemical, environmental, and life-related cellular physical characteristics of ...size-fractionated PMs is important because of their different degrees of harmful effects on human respiratory tracts and organ systems, causing severe diseases. This study evaluates the chemical components of size-fractionated PMs down to PM0.1 collected during a biomass-burning episode, including elemental/organic carbon and trace elements. Single particle sizes and distributions of PM0.1, PM0.5–0.1, PM1.0–0.5, and PM2.5–1.0 were analyzed by scanning electron microscopy and Zeta sizer. Two commonly used cell lines, e.g., HeLa and Cos7 cells, and two respiratory-related cell lines including lung cancer/normal cells were utilized for cell cytotoxicity experiments, revealing the key effects of particle sizes and concentrations. A high-speed scanning ion conductance microscope explored particle-stimulated subcellular physical characteristics for all cell lines in dynamics, including surface roughness (SR) and elastic modulus (E). The statistical results of SR showed distinct features among different particle sizes and cell types while a E reduction was universally found. This work provides a comprehensive understanding of the chemical, environmental, and cellular physical characteristics of size-fractionated PMs and sheds light on the necessity of controlling small-sized PM exposures.
Polyphenylene sulfide (PPS) non-woven fabrics are often used at high temperatures for bag filters in incinerating plants. Even though they degrade in the presence of acid gases, there has been not ...much information on the degradation of mechanical properties of PPS in nitric oxide (NO). At 200°C, which is generally the highest operational temperature of bag filters, PPS fabrics gradually lose their elongation even if the modulus is barely unaffected. On the other hand, at 250°C, which is near its melting temperature of 285°C, the modulus increases while the elongation decreases. Contrary to our first guess, PPS does not soften near its melting temperature and becomes even more rigid. Our hypothesis then becomes that crosslinking and branching dominate around 250°C, leading to the embrittlement of PPS bag-filter materials and severe strength loss. Therefore, it is our recommendation that the operational temperature of PPS bag filters should always be below 200°C and the NO concentration should be far below 1000 p.p.m., at which point chemical degradation occurs severely.
This study reports on an investigation of fine and coarse carbonaceous particulate matters (PM) in Tachileik, eastern Myanmar, during the dry and wet seasons of 2022. The carbon compositions, ...including organic carbon (OC) and elemental carbon (EC), in each size (PM10-2.5, PM2.5-1.0, and PM1.0-0.5) were determined by a carbon analyzer. The average total mass concentration of the three fractions of particle samples during the dry season was higher (51.23 ± 23.86 μg/m3) than that of the wet season (14.00 ± 5.26 μg/m3). The results indicate that OC and EC levels were highest for PM1.0-0.5 during the dry season and the sizes were similar for both seasons. The OC/EC ratios varied in different seasons, from 1.93 to 4.40 and 4.13 to 5.25 in the dry and wet seasons, respectively. EC was sub-divided into char-EC and soot-EC; the char-EC/soot-EC in the dry season was higher than in the wet season, signifying that biomass burning is the main particle source during the dry season. However, vehicle emissions dominated during the wet season. The effective carbon ratio (ECR) suggested that finer particles contributed more to global warming. This information is important in terms of air quality control and mitigation in Myanmar and elsewhere.
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•Size-fractionated particulate matters (PM10-2.5, PM2.5-1.0, PM1.0-0.5) in Myanmar were examined.•Organic carbon and elemental carbon in Myanmar contained the highest in PM1.0-0.5 during the dry season.•The influence of open biomass burning was greater during the dry season.•Effective carbon ratio suggested that finer particles contribute more to global warming.
Abstract
Kabul city, the capital of Afghanistan, has suffered from poor air quality for the last two decades. This study focuses on Kabul’s spatiotemporal characteristics of aerosol optical depth ...(AOD). The annual and long-term 20 years of AOD data were retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) a combination of Terra and Aqua satellites using the Google Earth Engine geospatial analysis platform to determine seasonal variation and long-term trend of the aerosols. The air mass backward trajectories were calculated using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Furthermore, ArcGIS 10.7.1 is used to visualize the AOD over the city. The results show high AOD in summer. However, autumn is recorded as the lowest average AOD season. In addition, the 20 years of data from 2001 to 2021 shows a slight increase in AOD. We suggest that the increase in AOD in the city is due to the rapid growth of the population. The cross-boundary atmospheric aerosols affect the air quality in the city.
The health risk of schoolchildren who were exposed to airborne fine and ultrafine particles (PM
) during the COVID-19 pandemic in the Jambi City (a medium-sized city in Sumatra Island), Indonesia was ...examined. A questionnaire survey was used to collect information on schoolchildren from selected schools and involved information on personal profiles; living conditions; daily activities and health status. Size-segregated ambient particulate matter (PM) in school environments was collected over a period of 24 h on weekdays and the weekend. The personal exposure of PM of eight selected schoolchildren from five schools was evaluated for a 12-h period during the daytime using a personal air sampler for PM
particles. The schoolchildren spent their time mostly indoors (~88%), while the remaining ~12% was spent in traveling and outdoor activities. The average exposure level was 1.5~7.6 times higher than the outdoor level and it was particularly high for the PM
fraction (4.8~7.6 times). Cooking was shown to be a key parameter that explains such a large increase in the exposure level. The PM
had the largest total respiratory deposition doses (RDDs), particularly during light exercise. The high level of PM
exposure by indoor sources potentially associated with health risks was shown to be important.
Addressing the air pollution problem in upper Southeast Asia (USEA) becomes critical due to its serious impacts on human health and the environment. This study aims to investigate the characteristics ...of ultrafine carbonaceous particles (PM0.1; Dp <≤ 0.1 μm) in Chiang Mai, Thailand, and Tachileik, Myanmar. Carbon compositions, including elemental carbon (EC) and organic carbon (OC) in PM0.1, were determined by a carbon analyzer. The range of particle mass ranged from 3.2 to 18.4 μg/m3 with an average of 8.3 ± 4.4 μg/m3 and 5.4–20.8 μg/m3 with an average of 10.2 ± 4.3 μg/m3 in Thailand and Myanmar, respectively. The ratio of the EC, Char-EC/Soot-EC ratio, was found to be more applicable than the OC/EC ratio for identifying the sources of the emission. The char-EC/Soot-EC ratios in the PM0.1 were less than 1.0 in the rainy season. Vehicle exhaust had a significant impact on these samples. However, the higher Char-EC/Soot-EC ratios indicate that biomass burning was a major source. The correlation for PM0.1 with all carbon profiles was strong, especially during the dry season, suggesting that they were produced from the same emission source. The OC/EC vs. EC correlation for PM0.1 at the Chiang Mai and Tachileik sites appears to be affected by open biomass fires. Our findings suggest that biomass combustion is a probable source of PM0.1 in Thailand and Myanmar. Therefore, it is crucial to prioritize the management of open burning and traffic to mitigate PM0.1 pollution in this region.
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•Carbon compositions of PM0.1 were compared between Thailand and Myanmar.•Contrasting PM0.1 sources during dry and wet periods were found.•Thailand and Myanmar reported 36% and 20% PM0.1 from secondary aerosol during dry season.•Traffic Emission is dominated to PM0.1 mass concentration during wet period.
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