It's the middle of summer and many cities are experiencing extreme heat and humidity levels. Perhaps it is apt then that the journal Environmental Health Perspectives has published a new study showing that the urban heat island effect (UHI) disproportionately affects people of colour. While you might think that this is not a surprising finding, given that many inner-city people in the United States and Canada tend to be poor and belong to a racial minority, what is interesting about the study is that it finds that the UHI is linked more closely with race than it is class. The study took into account such factors as income, home ownership, and neighbourhood density, and found that while people of colour who own their own homes are less likely to be affected by UHI than poor people, they are still significantly more likely than white people to suffer from UHI in general. This is a big deal because extreme heat causes fatalities every year as people are unable to find relief during punishing heat waves. The study recommends that cities invest in infrastructure such as trees in areas that are more susceptible to UHI in order to help alleviate the problem.