| Abstract: |
Fine particulate matter (PM2.5) has become the single most consequential air quality parameter for urban public health, since particles below 2.5 micrometres penetrate deep into the pulmonary alveoli and pass into systemic circulation, triggering inflammatory and oxidative processes linked to cardiovascular and respiratory disease. This paper examines the relationship between ambient PM2.5 concentrations and human health outcomes in urban areas through a secondary-data, quantitative-synthesis approach, drawing on air quality monitoring records, regulatory standards, and peer-reviewed epidemiological literature spanning three decades. Rather than generating new primary exposure measurements, the study compiles data from the World Health Organization, India's Central Pollution Control Board, the IQAir global monitoring network, and major cohort and meta-analytic studies to build a comparative picture of the PM2.5-health relationship in urban populations, with particular attention to Indian cities. The analysis finds that most urban centres worldwide, and an overwhelming majority in India, continue to exceed WHO guideline values by wide margins, and that this exceedance corresponds to consistently elevated relative risks for cardiovascular, respiratory, and all-cause mortality documented across independent cohorts on different continents and decades. The disease burden attributable to ambient PM2.5 in India runs from several hundred thousand to over a million deaths annually depending on which exposure-response function is applied, a spread that signals unresolved methodological tension within the field. These findings anchor the paper's central argument: PM2.5 is a determinant of urban population health rather than a peripheral environmental concern, and the conclusion returns to this argument, contending that regulatory tightening alone, without structural change in urban energy and transport systems, is unlikely to close the gap between present exposure and guideline safety. |
