Studies of heatwaves in American cities during the 1980s and 1990s observed that a good predictor for falling ill was poverty, and specifically a lack of air conditioning in the home. Surveys since then suggest that the dramatic fall in the number of Americans who sicken or die during heatwaves is a direct result of widening air-conditioner ownership, from 68% of American households in 1993 to nearly 90% today.
Fact: A statewide study of summer admissions to hospital in California, published in 2010, adjusted for household income, found that for each 10% increase in ownership of air conditioning there was an absolute reduction in cardiovascular disease of 0.76%, and of respiratory disease by 0.52%, for people over 65. For places less blessed than California, where risks include insect-borne diseases such as malaria and dengue fever, or high levels of toxic particulate matter in the air, the benefits of wider air-conditioning use could be far greater.
Good thing we have great HVAC contractors!