Effective ventilation is one of the most important tools in the fight against allergens. Not only does the correct amount of ventilation bring fresh air into your home, it also helps regulate humidity and moisture levels to control everything from mold to dust mites. The ideal level of humidity in most homes is 50 percent (you can test your humidity levels with simple moisture meters found at hardware or home improvement stores). At this level, the air in your bedroom will stay dry enough to prevent mold and mildew growth, but wet enough to keep dust and other allergens from circulating through the air. If mold is still an issue at this level, lower humidity to 40 percent.
If you can't reach this level of humidity by adjusting your heating and air conditioning systems, choose a separate dehumidifier unit just for the bedroom. Many models will allow you to set a desired humidity level, then will automatically adjust to keep the room at this level. Whether you're relying on your HVAC system or a separate unit, check that the filters are clean, and replace standard filters with more effective HEPA-versions.
One final tip: Don't be fooled by duct cleaning services that promise to improve your indoor air quality or relieve allergies. According to the U.S. Environmental Protection Agency (EPA), duct cleaning shouldn't be considered a routine maintenance procedure. Clean your ductwork only if you spot visible mold or pest infestations within the ducts.