Which AQI number should we believe in Mumbai?

But a site visit by Hindustan Times to ten private and government construction sites revealed data that appears misleading.

MUMBAI: Through the haze, experts see a smokescreen – the civic administration’s attempt to monitor air quality at construction sites, a key source of pollution in a city where poor air has, for the first time, sounded alarm bells.

At two construction sites in the same Shivaji Park locality in Dadar, the contrast was even sharper. The monitoring board on the left picture showed relatively low PM2.5 and PM10 levels of 36 and 37, while another nearby monitor displayed sharply higher readings of 100 and 114, despite both being in the same area. (Raju Shinde/HT Photo)

In May last year, the BMC mandated that developers and building contractors install monitors that display air quality levels (Air Quality Index or AQI) as well as levels of particulate matter. This was in response to litigation on Mumbai’s poor air