Asthma sufferers can benefit from both air purifiers and humidifiers but for different reasons. Asthma triggered by environmental factors such as irritants or allergens will benefit from an indoor air purifier to help remove these triggers from the air before they cause symptoms. A humidifier, on the other hand, is good for managing existing symptoms, moistening the air, and aids in promoting steady breathing. Too much humidity can make some asthma worse, so a humidifier should be used in moderation and only when symptoms flare up, not continuously as you would use a purifier.