Why Hot Cities Make Air Harder to Breathe

When summer heatwaves settle over concrete jungles, city dwellers face far more than sweltering asphalt and soaring energy bills. Dense metropolitan areas trap heat, creating a microclimate phenomenon known as the Urban Heat Island (UHI) effect. While higher temperatures are uncomfortable on their own, the physiological danger escalates when extreme heat acts as an atmospheric engine—concentrating fine particulate matter (2.5pm) and accelerating the chemical creation of ground-level ozone (O3) in the very air we breathe.