Both evaporative coolers (or "swamp coolers") and whole-house fans can help protect people indoors from airborne transmission of COVID-19 because they increase ventilation with outside air to cool indoor spaces. Evaporative coolers are used in dry climates. They use water to provide cooling and increase relative humidity indoors. When operating as intended (with open windows), these devices produce substantial increases in ventilation with outdoor air. Some evaporative coolers can be operated without using water when temperatures are milder, to increase ventilation indoors. Avoid using evaporative coolers if air pollution outside is high and the system does not have a high-efficiency filter.
For additional information on selecting and using evaporative coolers, see the Department of Energy's evaporative coolers web page.
Whole-house fans are also typically used to provide cooling by pulling air through open windows and doors and exhausting it through the roof. When operated as intended, with open windows, these devices produce substantial increases in ventilation with outdoor air throughout a house. Avoid using whole-house fans if air pollution outside is high.
For additional information on selecting and using whole-house fans, see the Department of Energy's whole-house fans web page.
However, by itself, an evaporative cooler or whole-house fan is not enough to protect people from COVID-19. When used along with other best practices recommended by the Centers for Disease Control and Prevention, operating an evaporative cooler or whole house fan can be part of a plan to protect yourself and your family.