The National Fire Protection Association suggests homeowners check their chimneys annually; however, most people wait until it gets cold! By then, we become so busy that sometimes there could be a month-long wait,” Smith said. The ideal time to do it is in July and August, when we are not that busy, he added. Air duct cleaning should be done every 3-5 years, but people with pets and allergies should have it done more often – every 2-3 years, Smith said. He also emphasized that dryer vent cleaning is important because there are approximately 15,000 dryer vent fires a year (nationally).