Modeling the impact of sea-spray on particle concentrations in a coastal city

Impact of the National Clean Air Programme (NCAP) on the particulate matter pollution and associated reduction in human mortalities in Indian cities

The study of particulates in cities holds significant importance in the evaluation of atmospheric conditions, comprehension of health ramifications and provision of valuable insights for the development of efficient pollution abatement measures and policies. Governments worldwide are currently enacting rigorous regulations aimed at mitigating particulate matter (PM), as it seriously affects air quality, public health, ecosystem, and visibility over a region. In this context, the Indian government launched the National Clean Air Programme (NCAP) in 2019 to reduce the PM10 emissions to 20-30 % by 2024-25, as compared to that of 2017-18, by enforcing city-specific policies and mitigation strategies. Here, we assess the changes in PM10 over 28 Indian cities using the measurements collected by the Central Pollution Control Board (CPCB) for the period of 2018-2022. The concentration of PM with a diameter of 10 μm or less (PM10) is comparatively high, about 80-120 μg/m3, in the cities in the Indo-Gangetic Plain (IGP) and Central India (CI). Conversely, the levels of PM10 are lower (about 40 μg/m3) in the Peninsular regions (e.g. Hubballi). Most cities considered (20 out of 28) show a decline in PM10 concentration (about 15-60 %) in 2022 as compared to that in 2018. This reduction resulted in a total of 62,219 excess mortalities avoided in 20 Indian cities in 2021 compared to 2018. Nevertheless, there are 8 cities where the levels of PM10 are greater than that in 2018 (e.g. Kolkata and Durgapur). Thus, this study finds that the implementation of NCAP has been successful in decreasing PM10 levels in India and improving public health by reducing fatalities. Therefore, it is recommended to enforce stringent rules to achieve the goals set by NCAP.

Harbor and Intra-City Drivers of Air Pollution: Findings from a Land Use Regression Model, Durban, South Africa

Multiple land use regression models (LUR) were developed for different air pollutants to characterize exposure, in the Durban metropolitan area, South Africa. Based on the European Study of Cohorts for Air Pollution Effects (ESCAPE) methodology, concentrations of particulate matter (PM₁₀ and PM_2.5), sulphur dioxide (SO₂), and nitrogen dioxide (NO₂) were measured over a 1-year period, at 41 sites, with Ogawa Badges and 21 sites with PM Monitors. Sampling was undertaken in two regions of the city of Durban, South Africa, one with high levels of heavy industry as well as a harbor, and the other small-scale business activity. Air pollution concentrations showed a clear seasonal trend with higher concentrations being measured during winter (25.8, 4.2, 50.4, and 20.9 µg/m³ for NO₂, SO₂, PM₁₀, and PM_2.5, respectively) as compared to summer (10.5, 2.8, 20.5, and 8.5 µg/m³ for NO₂, SO₂, PM₁₀, and PM_2.5, respectively). Furthermore, higher levels of NO₂ and SO₂ were measured in south Durban as compared to north Durban as these are industrial related pollutants, while higher levels of PM were measured in north Durban as compared to south Durban and can be attributed to either traffic or domestic fuel burning. The LUR NO₂ models for annual, summer, and winter explained 56%, 41%, and 63% of the variance with elevation, traffic, population, and Harbor being identified as important predictors. The SO₂ models were less robust with lower R² annual (37%), summer (46%), and winter (46%) with industrial and traffic variables being important predictors. The R² for PM₁₀ models ranged from 52% to 80% while for PM_2.5 models this range was 61–76% with traffic, elevation, population, and urban land use type emerging as predictor variables. While these results demonstrate the influence of industrial and traffic emissions on air pollution concentrations, our study highlighted the importance of a Harbor variable, which may serve as a proxy for NO₂ concentrations suggesting the presence of not only ship emissions, but also other sources such as heavy duty motor vehicles associated with the port activities.

A review of the distribution of particulate trace elements in urban terrestrial environments and its application to considerations of risk

We review the evolution, state of the art and future lines of research on the sources, transport pathways, and sinks of particulate trace elements in urban terrestrial environments to include the atmosphere, soils, and street and indoor dusts. Such studies reveal reductions in the emissions of some elements of historical concern such as Pb, with interest consequently focusing on other toxic trace elements such as As, Cd, Hg, Zn, and Cu. While establishment of levels of these elements is important in assessing the potential impacts of human society on the urban environment, it is also necessary to apply this knowledge in conjunction with information on the toxicity of those trace elements and the degree of exposure of human receptors to an assessment of whether such contamination represents a real risk to the city's inhabitants and therefore how this risk can be addressed.