In 1842 edwin chadwick, a British social reformer, published his “Report on the Sanitary Condition of the Labouring Population”. By documenting evidence of social and geographic inequalities in health, Chadwick showed that poor sanitation was associated with poor health. The report eventually led British cities to organise clean water supplies and to centralise their sewage systems, in turn reducing the prevalence of infectious diseases, in particular cholera. Similar reforms around the world in the 20th century tackled food safety and outdoor-air pollution. Now a new public-health priority is becoming apparent: making indoor air cleaner.

Take schools. They are “chronically under-ventilated”, according to the Lancet covid-19 commission. A study of 100 American classrooms found 87 with worryingly low ventilation rates. Across Denmark, France, Italy, Norway and Sweden, researchers found that indoor-air quality in 66% of classrooms fell short of healthy standards. In America nearly one child in 13 has asthma—a condition triggered by allergens often found in schools. Outdoor-air pollution can penetrate inside buildings—childhood exposure can affect neurodevelopment and academic performance, and cause cancer...

The Economist: It is time to clean up the air in buildings