Chemical characterization of fine particles (PM2.5) at a coastal site in the South Western Mediterranean during the ChArMex experiment

Sources, Ionic Composition and Acidic Properties of Bulk and Wet Atmospheric Deposition in the Eastern Middle Adriatic Region

Atmospheric bulk and wet deposition samples were collected simultaneously at the background coastal site in the Eastern Middle Adriatic region in order to assess the impact of major ions (Cl^-, NO₃^-, SO₄^2-, Na⁺, K⁺, NH₄⁺, Mg²⁺, Ca²⁺) on deposition acidity and distinguish the main sources. Higher ion levels were observed during the cold period, especially for Cl^-, Na⁺, Mg²⁺ and K⁺. Dust intrusion caused significant increases in levels of Ca²⁺, Mg²⁺ and K⁺, while open-fire events increased the levels of K⁺. Deposition acidity showed seasonal differences as well as the influence of dust intrusion. Low ionic balance ratios indicated acidic deposition properties and the presence of organic anions. The highest neutralization ability was found for Ca²⁺, Na⁺ and NH₄⁺. Several natural (marine, crustal) and anthropogenic sources were determined, as well as the formation of secondary aerosols. Wet deposition was characterized by higher contribution of sea salt fraction compared to bulk deposition and lower contribution of crustal fraction.

Characteristics and Risk Assessment of Environmentally Persistent Free Radicals (EPFRs) of PM2.5 in Lahore, Pakistan

Environmentally persistent free radicals (EPFRs) are an emerging pollutant and source of oxidative stress. Samples of PM_2.5 were collected at the urban sites of Lahore in both winter and summertime of 2019. The chemical composition of PM_2.5, EPRF concentration, OH radical generation, and risk assessment of EPFRs in PM_2.5 were evaluated. The average concentration of PM_2.5 in wintertime and summertime in Lahore is 15 and 4.6 times higher than the national environmental quality standards (NEQS) of Pakistan and WHO. The dominant components of PM_2.5 are carbonaceous species. The concentration of EPFRs and reactive oxygen species (ROS), such as OH radicals, is higher in the winter than in the summertime. The secondary inorganic ions do not contribute to the generation of OH radicals, although the contribution of SO₄²⁺, NO₃^-, and NH₄⁺ to the mass concentration of PM_2.5 is greater in summertime. The atmospheric EPFRs are used to evaluate the exposure risk. The EPFRs in PM_2.5 and cigarette smoke have shown similar toxicity to humans. In winter and summer, the residents of Lahore inhaled the amount of EPFRs equivalent to 4.0 and 0.6 cigarettes per person per day, respectively. Compared to Joaquin County, USA, the residents of Lahore are 1.8 to 14.5 times more exposed to EPFRs in summer and wintertime. The correlation analysis of atmospheric EPFRs (spin/m³) and carbonaceous species of PM_2.5 indicates that coal combustion, biomass burning, and vehicle emissions are the possible sources of EPFRs in the winter and summertime. In both winter and summertime, metallic and carbonaceous species correlated well with OH radical generation, suggesting that vehicular emissions, coal combustion, and industrial emissions contributed to the OH radical generation. The study's findings provide valuable information and data for evaluating the potential health effects of EPFRs in South Asia and implementing effective air pollution control strategies.

Water-soluble ions and source apportionment of PM2.5 depending on synoptic weather patterns in an urban environment in spring dust season

Emission sources and meteorological conditions are key factors affecting the intensity and duration of air pollution events. In the current study, using the daily concentrations of PM_2.5 (particulate matter with a diameter ≤ 2.5 μm) and the water-soluble ions thereof in Lanzhou from March 1, 2021, to May 31, 2021, we investigated the contributions of emission sources and locations of potential sources through positive matrix factorization and potential source contribution function analysis. In addition, synoptic weather patterns affecting pollution were typed using T-model principal component analysis. The results revealed that the average concentrations of PM_2.5 for the entire spring, dust storm days, and normal days were 54.3, 158.1 and 33.0 μg/m³, respectively. During dust storm days, sulfate produced from primary emissions was mainly present in the form of K₂SO₄, Na₂SO₄, MgSO₄, and CaSO₄, and nitrate was mainly produced through secondary conversion and took the form of NH₄NO₃. Dust, industrial entities, biomass combustion, metal smelting, secondary aerosol, and sea salt contributed to 32.0, 29.8, 13.4, 11.2, 10.8 and 2.7% of the spring PM_2.5, respectively, in Lanzhou. The main potential sources of PM_2.5 during the normal days were in the western parts of Lanzhou. Dust storms entered Lanzhou through the Hexi Corridor from several dust sources: southeastern Kazakhstan, Mongolia, the Kurbantungut Desert, and the Badain Jaran Desert. The northwest high-pressure; northern strong high-pressure and southwest low-pressure; northwest high-pressure and southwest high-pressure synoptic weather circulation types were prone to dust storms. Our results may provide a basis for local environmental governance.

A city-level analysis of PM2.5 pollution, climate and COVID-19 early spread in Spain

PURPUSE

The COVID-19 outbreak has escalated into the worse pandemic of the present century. The fast spread of the new SARS-CoV-2 coronavirus has caused devastating health and economic crises all over the world, with Spain being one of the worst affected countries in terms of confirmed COVID-19 cases and deaths per inhabitant. In this situation, the Spanish Government declared the lockdown of the country.

METHODS

The variations of air pollution in terms of fine particulate matter (PM_2.5) levels in seven representative cities of Spain are analyzed here considering the effect of meteorology during the national lockdown. The possible associations of PM_2.5 pollution and climate with COVID-19 accumulated cases were also analyzed.

RESULTS

While the epidemic curve was flattened, the results of the analysis show that the 4-week Spanish lockdown significantly reduced the PM_2.5 levels in only one city despite the drastically reduced human activity. Furthermore, no associations between either PM_2.5 exposure or environmental conditions and COVID-19 transmission were found during the early spread of the pandemic.

CONCLUSIONS

A longer period applying human activity restrictions is necessary in order to achieve significant reductions of PM_2.5 levels in all the analyzed cities. No effect of PM_2.5 pollution or weather on COVID-19 incidence was found for these pollutant levels and period of time.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-022-00786-2.