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