Assessing Delhi Region's air quality using geospatial technologies: a comparative analysis of pollution trends during the COVID period (2018-2023).

This research examines trends in air quality in Delhi from 2018 to 2023 based on geospatial tools and statistical techniques, such as violin plot analysis, one-way analysis of variance (ANOVA), Tukey honestly significant difference (HSD), and Kriging interpolation. Air pollution measurements from 38 monitoring stations were evaluated to identify spatial and temporal patterns in the major pollutants (PM_2.5, PM₁₀, NO₂, SO₂, and ozone). The reports show a massive decline in the levels of PM_2.5 from 242.91 µg/m³ in 2018 to 99.51 µg/m³ in 2022, with similar downward trends being reflected for PM₁₀ (214.66 µg/m³ in 2019 to 106.88 µg/m³ in 2023) and NO₂ (46.61 µg/m³ in 2018 to 14.99 µg/m³ in 2023). SO₂ was comparatively static, with irregular industrial spikes, while the level of ozone varied, touching a high of 160 µg/m³ in some zones. COVID-19 lockdown contributed to a major decrease in levels of pollution, with PM_2.5 and PM₁₀ falling by more than 40%. Violin plot analysis showed fluctuations in pollutant concentrations between various regions, where localized changes were evident. One-way ANOVA and Tukey HSD tests also certified statistically significant variation in pollutant levels between varied phases, underlining the effects of lockdown practices. Spatial interpolation by Kriging resulted in high-resolution concentration maps, giving a complete picture of the distribution of pollution. The findings help deepen knowledge of air quality trends and guide policy interventions to reduce pollution and enhance public health in Delhi.