Analyzing air quality data from the US Consulate, Smart Air found that Mumbai’s air quality worsened 15% in 2018 compared to last year. This extra smog pushes Mumbai to an average of more than seven times the World Health Organization’s annual limit.
Mumbai’s air quality started 2018 at higher levels. Yet the largest difference over 2017 was the summer. In the summer, Mumbai air pollution soared over last year’s, with July reaching over three times 2017 levels. Winter 2018 has seen a slight respite.
With this worsening, Mumbai’s air quality is breaking away from Hyderabad, which used to have similar levels of pollution. Mumbai is now third among major Indian cities, although still 30% lower than Delhi.
The analysis is based on PM2.5 pollution, particles smaller than 2.5 microns in diameter that can penetrate deep into the lungs and even enter the bloodstream. Studies have shown that PM2.5 raises blood pressure, inflammation, and rates of heart attacks and strokes.
The US Consulate data is open for researchers, although it is limited. It comes from only one pollution sensor in the city, and pollution can vary between neighborhoods.
Protect yourself: Despite the harms of PM2.5, studies have found that wearing masks prevents physiological harm to the body, and placebo-controlled studies of air purifiers have found that removing particulate in the home has positive effects on blood pressure, inflammation, and immune response.
Smart Air provides empirically backed, no-nonsense purifiers and masks to help air-breathers protect themselves and their family. Smart Air is a certified B Corp founded to publicize the simple science behind air purifiers and masks, thereby lowering the cost of breathing clean air.
Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.