“Certain types of air conditioners that exhaust air from the home, including some portable ones, can do so faster than fresh outdoor air can come in, creating negative pressure or depressurization in the home…this can draw CO back into the home from fuel-burning appliances, such as furnaces, water heaters and ranges…have working CO alarms and open a window or door slightly to allow fresh air into the home when running an air conditioner that exhausts air outdoors…Other mitigation measures include regularly inspecting fuel-burning appliances, checking that external exhaust vents are clear of debris, and avoiding running multiple devices that exhaust air from the home at the same time — such as kitchen or bathroom exhaust fans and air conditioners that exhaust indoor air outdoors…”
