Delhi: Why India caps pollution reading at 500 when the air is far more toxic

India's air quality framework hasn't been comprehensively revised since 2009 and needs an update, say experts.

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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?