PM2.5 inhalation exposure and associated health risk in young adults at University campus, Delhi, India

Abstract

The present study determines PM₂.₅ concentrations during winter months (late October 2023–early January 2024) to assess the inhalation exposure-related health risks among young adults in the University campus in Delhi. The winter mean PM₂.₅ concentration (269.35 ± 143.43 μg/m³) was ~7 times higher than the National Ambient Air Quality Standards (NAAQS) and ~18 times the World Health Organization (WHO) standard. Health risk analyses were conducted using the U.S. Environmental Protection Agency (USEPA) inhalation risk assessment framework together with a Relative Risk (RR) model recommended by WHO. Seasonal Hazard Quotient (HQₛₑₐₛₒₙₐₗ) values during winter exceeded the safety threshold of unity, i.e. ~5–6 times higher than summer and monsoon levels, indicating pronounced short-term non-carcinogenic risk during peak pollution periods. In contrast, three-year Hazard Quotient (HQ₃ᵧᵣ) values, remained above unity despite being lower than winter peaks, suggesting sustained non-carcinogenic risk over campus residence. Gender-specific assessment showed marginally higher HQ₃ᵧᵣ values among males due to differences in inhalation rate and body weight. The RR model indicate a projected 1.65-fold increase in cardiopulmonary mortality and a 2.11-fold increase in lung cancer-related mortality under prevailing annual ambient PM₂.₅ concentrations, reflecting long-term risk rather than immediate disease occurrence within the cohort. Health status surveys were conducted among young adults and revealed with 10.3% of respondents had respiratory conditions (bronchitis or asthma), whereas 60.7% reported worsened symptoms such as coughing, sneezing, shortness of breath, or eye irritation during highly polluted winter months. Such observations also align with empirical data and provide a clearer understanding of the on-ground health impacts. In reference to the annual mean PM₂.₅ concentration (98.72 ± 74.51 μg/m³) at the University of Delhi North Campus [Central Pollution Control Board (CPCB) monitoring station] in 2023, the exposure was found to be associated with reductions in life expectancy at the population level. Substantial longevity gains could be achieved by meeting NAAQS or WHO's annual standards for PM2.5 (AQLI, 2025). Overall, the findings demonstrate that wintertime PM₂.₅ exposure poses considerable health risks to young adults, underscoring the urgency of long-term air quality management in urban academic settings and establishing a baseline for future mitigation-oriented research.