Air quality change and public perception during the COVID-19 lockdown in India

This study aims at analyzing the change in air quality following the COVID-19 lockdown in India and its perception by the general public. Air quality data for 100 days recorded at 193 stations throughout India were analyzed between 25th March to 17th May 2020. A nationwide online survey was conducted to obtain public perceptions of air quality improvement (n = 1750). On average, approximately 40% improvement in the air quality index was observed, contributed by a reduction in 40% of PM₁₀, 44% of PM_2.5, 51% of NO₂ and 21% of SO₂. There was a significant difference between the levels of all the pollutants before and after the lockdown (p < 0.05), except ozone. The correlation between PM₁₀ and PM_2.5 with ozone was significant after the lockdown period, indicating that a significant portion of the particulates present in the atmosphere after the lockdown period is secondary. The values of PM_2.5/PM₁₀ were found to be >0.5 in North East states and this observation points to the long-distance transport of PM_2.5 from other places. The survey for public perception showed that 60% of the respondents perceived improvement in air quality. Household emissions were perceived to be a significant source of pollution after the lockdown. An odds ratio (OR) of 17 (95%, CI: 6.42, 47.04) indicated a very high dependence of perception on actual air quality. OR between air quality and health improvement was 5.2 (95%, CI: 2.69, 10.01), indicating significant health improvement due to air quality improvement. Google Trends analysis showed that media did not influence shaping the perception. There was a significant improvement in the actual and perceived air quality in India after the COVID-19-induced lockdown. PM₁₀ levels had the most decisive influence in shaping public perception.