Extreme heatwaves spread as US told to expect hot and smoky summer

Smoke from unchecked Canada wildfires hits air quality in north-east as further south 80m American under excessive heat alerts

Extreme heatwaves are continuing to spread across the country as meteorologists warn Americans to prepare for a hot and smoky summer. With the 235 out-of-control Canadian wildfires showing no signs of dying down, smoke has drifted south into the US and shrouded multiple cities including Chicago and Detroit in a thick haze.

There are no signs of the relief coming for the next week or longer, according to the National Oceanic and Atmospheric Administration's Weather Prediction Center.

42% have experienced short-term injury or illness

23% report complications to an existing chronic condition

15% have suffered a long-term injury or a new chronic condition