PHILADELPHIA (WPVI) -- With smoke blowing into the Philadelphia region from the wildfires in Canada, you may have heard a lot about the Air Quality Index or AQI. But what it is, exactly? The Air ...

This special report focuses on the severe air pollution in Delhi, where the overall Air Quality Index (AQI) has reached a ...

The air quality index (AQI) is a public health tool designed to communicate air pollution levels or the quality of air in ...

In recent days, the air quality index has been at "Unhealthy" levels in New York City from the Canadian wildfires smoke. People have been warned to avoid outdoor physical activities. Those who spend ...

Delhi’s air quality deteriorated sharply on Thursday, with the city’s overall Air Quality Index (AQI) touching 400 and ...

Delhi woke up to a blanket of dense and lingering haze on Thursday as the capital city’s overall Air Quality Index (AQI) ...