Is it helpful to air out rugs and mattresses outside?

One major advantage the outdoor air has over indoor air is that, on sunny days, it contains a significant amount of ultraviolet radiation from the sun. While UV rays are harmful to your skin, they actually serve as effective disinfectants, killing bacteria. So, if you place a rug in a sunny spot, allowing it to soak up hours of sunlight, you are using the sun's rays to sanitize it. For large items like mattresses or area rugs, it's one of the most affordable ways to eliminate bacteria — after all, you can't toss a mattress into the washer!

Ultraviolet light is used as a disinfectant in many products. For example, UV light is used in swimming pool systems to disinfect pool water by passing it through strong UV light. Many municipalities also use UV light to enhance the effects of chlorine in treating drinking water. There are even devices that use UV light to sanitize your toothbrush!

In developing countries, there have been trials involving clear plastic soda bottles filled with contaminated drinking water. The bottles are left in the sunlight, which helps to reduce bacteria in the water. See, for example, Sun and water: an overview of solar water treatment devices.