The capital Delhi is often criticized for its high levels of winter pollution.
Mumbai, with its vast coastline, is more polluted than Delhi.
Mumbai is now part of a growing number of Indian cities with bad air quality.
Experts believe that poor weather conditions, rapid construction and increased pollution from vehicle emissions are all factors contributing to the decline in air quality.
According to government data, the level of PM2.5 – fine particulate matter which can clog lungs or cause a host diseases – was 308 in Delhi on Friday morning at 8.30 am [local time], as compared to Delhi’s reading (259).
A reading of 200-300 is considered to be poor, while a reading of 300-400 is considered to be very poor. Many Indian cities such as Delhi, Kolkata and Kanpur often have PM2.5 levels that are well above the safe limit.
According to the AQI, a figure between zero and fifty is considered “good”, while a figure between 51 and 100 would be considered “satisfactory”.
Cherylann Mollan. BBC News, Mumbai
This morning I felt two things when I woke up: it was colder than usual and it was making it harder for me to breathe. Later, I learned that the latter was due to Mumbai’s poor air quality.
Last week I had just traveled to Delhi, a city notorious for its bad air. You can feel the difference as soon as you arrive in Delhi. You immediately feel the weight of the air and notice the pollution. Every breath requires a little more effort. It was a pleasure to be back in Mumbai at the end the week.
Today, however, Mumbai’s citizens found themselves in the exact same boat. Our air is actually worse.
Local hospitals in Mumbai reported an increase in patients coming in with breathing problems and other conditions related to poor air quality.
Doctors advise people to wear masks and not go out if they aren’t necessary. Mumbai’s civic officials claim they are taking immediate steps to improve the quality of the air.
Poor air quality is a major problem in Indian cities. According to a Lancet study, pollution caused more than 2.3 million deaths prematurely in India in 2019.