From The New York Times, Monday, July 12, 2010:
The battle against mosquitoes is often fought with chemical repellents. DEET, the most popular choice, is highly effective, but it can be toxic, smelly and irritating.
For those who prefer a chemical-free repellant, a plain and simple house fan just might do the trick.
Studies have found that wind is an effective method against mosquitoes and other airborne pests. The reason seems obvious: it prevents them from circling and landing on you, like a windstorm keeping a plane from its descent. But that is not entirely the case. A fan dilutes and disperses the carbon dioxide you exhale. Carbon dioxide is one of the major chemicals that attract mosquitoes. The wind from a fan also cools you off. Sweat, lactic acid and body heat attract mosquitoes — factors that a fan can help minimize.
In one study in 2003, entomologists at Michigan State University used traps set up in a wetland by the C.D.C. to attract mosquitoes. Releasing carbon dioxide attracted more pests to the trap, and the more carbon dioxide, the more mosquitoes.
Using fan-generated wind of various speeds helped keep them away. But there was no link between wind “velocity” and “mosquito body mass.”
“We recommend that fan-generated wind should be pursued as a practical means of protecting humans or pets from mosquitoes in the backyard setting,” they wrote.
For an indoor setting, a fan on medium or high speed should do the job.
THE BOTTOM LINE
Using a fan can ward off mosquitoes.