Mumbai on Tuesday morning recorded an air quality index (AQI) value of 14, logging the city’s second cleanest air day on record since monitoring began in 2015, as per data from the System of Air Quality and Weather Forecasting and Research’s (SAFAR) network of ambient air quality monitors in the city.
Earlier, on September 4, 2019, the AQI had touched a record low of 12.
Air quality on Tuesday morning also marked the city’s cleanest air of the year, improving on the previous day’s AQI of 28, thanks to recent widespread showers and strong winds prevailing since the onset of the southwest monsoon over the city on June 13.
“Both Monday and Tuesday this week are among the cleanest ever air days for Mumbai since we began recording pollution levels in 2015. It can be attributed to favourable weather conditions. Recent rains have washed airborne pollutants out of the atmosphere and strong winds are keeping them from accumulating again,” Gufran Beig, project director, SAFAR said.
On the same day that Mumbai saw one of its lowest air pollution levels, however, an updated index known as the Air Quality Life Index (AQLI), which is published annually by the University of Chicago’s Energy Policy Institute (EPIC), found that exposure to PM2.5 — respirable particulate matter less than 2.5 micrometres in diameter — is potentially reducing the lifespan of Mumbai citizens by an average of 2.8 years, as against the national average of 5 years.
The updated AQLI, published on Tuesday, uses air pollution data till 2020, and translates it into impact on life expectancy using an epidemiological approach similar to that deployed near the Huai River in China, where communities are provided free or subsidised coal for indoor heating. By tracking these communities in a previous study, EPIC’s researchers were able to measure the effect of sustained exposure to high levels of pollution on a person’s life expectancy. They deduced that life expectancy is reduced by 0.98 years for every 10μg/m3 of sustained exposure to particulate matter.
The index also shows that the average annual concentration of PM2.5 in Mumbai decreased over the course of the first pandemic year, falling from 47.9ug/m3 in 2019 to 33.4ug/3 in 2020, which experts said it not surprising given the slowdown in emissions-heavy activities during prolonged periods of lockdown in 2020.
Dr Lancelot Pinto, pulmonologist and epidemiologist from Hinduja Hospital, emphasised that the link between ambient air pollution and life expectancy has been reported in multiple studies and WHO guidelines.
“Air pollution has a strong link with respiratory disease through diseases such as chronic obstructive pulmonary disease (COPD), which is the third leading cause of death in India, as well as asthma and other underlying respiratory illnesses. There is also a link with cardiovascular diseases through its effects on heart rate, blood pressure,” said Pinto. “It [AQLI] is important for policymakers because the focus on health is often on helping to build healthcare infrastructure, which addresses disease once it has occurred (tertiary prevention). Primary prevention might yield much higher returns, by promoting health, and preventing, rather than curing disease.”