Weather tracker: 100m people in US under air quality warnings as wildfires spread

A man shelters from the sun at Barton Creek in Austin, Texas, as a heatwave gripped large parts of the southern US. Photograph: Suzanne Cordeiro/AFP/Getty Images

The US has faced severe weather conditions in the past week, with air quality warnings issued across the midwest and north-east, affecting more than 100 million people.

Smoke from more than 450 Canadian wildfires spread across the US, resulting in poor air quality, with some states labelled as having “unhealthy” or “very unhealthy” conditions.