Goa/MumbaiMumbai’s air had more fine pollutant particles that easily enter the human body than Delhi did in 2018. The percentage share of the tiny polluting PM2.5 particles (particulate matter of the size 2.5 microns) in the slightly larger PM10 (more than 10 micrometres in diameter) pollutant particles was at an annual average of 60% in Mumbai, 55% in Ahmedabad, 53% in Pune, and 49% in Delhi in 2018, according to data released by the System of Air Quality Weather Forecasting and Research (SAFAR) at an air quality conference in Goa last week.To be sure, the absolute levels for PM2.5 and PM10 individually in each city was much more in Delhi when compared to Mumbai. However, due to meteorological factors in Mumbai, which allowed the tinier, deadlier pollutants to stay in the air longer, the percentage share of PM2.5 in PM10 was higher for the city, said SAFAR researchers.“Mumbai had the highest share of finer toxic particles (PM2.5), which are more hazardous to health, in total PM10 across 2018,” said Gufran Beig, project director, SAFAR. Beig said the high humidity allowed the finer pollutant particles to get suspended in Mumbai’s air for longer. Independent researchers also validated the findings of the study. “High moisture and temperature allows these finer particles to be trapped along with emissions from combustion sources, in the city’s air for longer as compared to other landlocked cities,” said Polash Mukerjee, lead (air pollution), Natural Resources Defence Council (NRDC) India.Air pollution is quickly becoming one of the biggest problems to be tackled by Maharashtra, which saw 1.08 lakh air pollution-related deaths in 2017, according to a Lancet study.