Lahore was ranked the second most polluted city in the world in terms of air quality on Sunday, according to air quality monitoring platform IQAir. The Air Quality Index (AQI) is a measure of the concentration of various pollutants in the air, such as fine particulate matter (PM2.5), coarse particulate matter (PM10) and nitrogen dioxide (NO2), and ozone (O3). Any IQAir AQI ranking above 150 is considered “unhealthy” and above 200 is considered “very unhealthy”. The AQI reading for Lahore stood at a very unhealthy 189; it was just beaten by Delhi, which registered a reading of 212 around 7:30pm. Additionally, levels of the pollutant PM2.5 were measured at 109 microgrammes per cubic metre of air (μg/m³), 21.8 times higher than the World Health Organisation’s annual PM2.5 guidelines. PM2.5 particles are floating particulate matter in the air measuring 2.5 micrometres in diameter or less, according to IQAir. PM2.5 is so small that it can be absorbed into the bloodstream upon inhalation. IQAir recommended on its w...