Being inside with the windows closed does not completely protect you from the smoke caused by wildfires, early findings by University of Manchester researchers suggest. And opening windows during hot weather, they show, almost certainly exacerbates the problem of indoor air pollution caused by the fires. Every monitored home in the Cystic Fibrosis Trust funded study exceeded the World Health Organization’s 24-hour guideline for fine particle pollution on 17 July, when outdoor smoke levels peaked. The researchers say that following the UK Health Security Agency’s guidance on wildfire smoke by staying indoors and closing windows should help reduce the pollution. “Following the simple but often repeated instruction of going indoors and shutting the windows will only give you some protection from wildfire smoke, and keeps heat in the home.