Air pollution in New Delhi: a secondary data analysis of the indices from 2021 to 2024

Background: Air pollution remains one of the most pressing environmental and public health concerns in New Delhi, often ranked among the world’s most polluted cities. This study aimed to assess the trends in major air quality indicators, PM2.5, PM10, NO₂, SO₂, CO, O₃, and AQI from 2021 to 2024, using secondary data from Central Pollution Control Board (CPCB) and validated platforms. Methods: The data were analyzed using retrospectively using descriptive statistics, ANOVA, and Kruskal-Wallis tests, supported by visualizations and statistical analysis through Tableau and STATA 16.0 respectively. Results: The findings suggested a recurring seasonal pattern, with pollution levels peaking during winter months (November-January) across all years. PM2.5 and PM10 concentrations consistently exceeded WHO’s safe limits by up to tenfold, with AQI levels frequently falling into the "very poor" to "severe" categories. While a marginal decline in AQI was observed in January 2024, pollutants like NO₂ and CO surged during winters, reflecting continuing emissions from automobiles and industries. During summers (February-June), ozone levels soared, whereas SO₂ levels remained stable then spiked in early 2024. Conclusions: Delhi’s air quality remains hazardous. There is an urgent need for evidence-based, sustainable interventions targeting major pollutants and emphasizing health-centered urban planning for a cleaner, greener and more livable city.