India's Air Quality Cap: Why Readings Are Limited to 500

Sun Nov 16 2025 06:22:14 GMT+0200 (Eastern European Standard Time)

As air pollution worsens in northern India, the official air quality index tops out at 500, raising questions about trust and transparency in air quality reporting.

With millions in northern India facing hazardous air quality that frequently exceeds the official cap of 500 AQI, confusion reigns over which readings to trust. Government-backed monitors limit their outputs to this threshold, while private platforms often report much higher figures. Experts discuss the implications of this discrepancy, which stems from a health hazard assumption and a desire to avoid public panic. Calls for revising the air quality index emphasize the need for accurate representation of pollution's impact.

For millions across northern India, the November air tastes ashy, the sky looks visibly hazy and merely stepping outside feels like a challenge.

For many, their morning routine starts with checking how bad the air is. But what they see depends entirely on which monitor they use.

Government-backed apps like SAFAR and SAMEER top out at 500 - the upper limit of India's AQI (air quality index) scale, which converts complex data on various pollutants such as PM2.5, PM10, nitrogen dioxide, sulphur dioxide, carbon monoxide and ozone, into a single number.

But private and international trackers such as IQAir and open-source monitoring platform AQI routinely show far higher numbers, often shooting past 600 and even crossing 1,000 on some days.

This contradiction leaves people asking the same question every year: Which numbers should they trust? And why doesn't India officially report air quality beyond 500?

India's official air-quality scale shows readings above 200 pose clear breathing discomfort to most people on prolonged exposure. Readings above 400 and up to 500 are classified as severe and affect healthy people while also seriously impacting those with existing diseases.

The scale, however, does not go beyond 500 - a cap set more than a decade ago when the National Air Quality Index was launched. It was assumed that the health impact would be the same no matter how much higher it goes because we had already hit the worst.

Gufran Beig, founder-director of SAFAR, admits that the 500 cap was originally set to avoid creating panic, but it effectively flattens the data, treating anything above 500 the same.

Experts criticize this limitation and argue that it misrepresents the true state of pollution, as global platforms do not impose such caps.

Moreover, there are significant differences in how countries define hazardous air. For example, the World Health Organization classifies PM2.5 levels above 15 micrograms per cubic meter in a 24-hour period as hazardous, while in India, the threshold is 60 micrograms.

Calling for a revision of India's air quality standards, experts stress the need for incorporating real-time data and using more accurate measurement technologies. Measures are essential for reflecting the escalating effects pollution has on public health.