An estimated 50 million people in the United States, approximately 20 percent of the population, suffer from allergies -- a figure that has doubled in the last decade. Seasonal allergies or hay fever are the most prevalent, affecting approximately 35 million Americans. MayoClinic.com offers help for people with all types of allergies, including hay fever and seasonal allergies. Even the cleanest homes can contain common allergens such as dust mites, mold, pet dander, and residue from mice or cockroaches. Homeowners can take a number of steps to prevent their homes from harboring common allergens. Home modifications can decrease the exposure to these allergens and may help reduce the inhabitant's allergy and asthma symptoms. A new feature on MayoClinic.com offers some simple tips and suggestions to help people allergy-proof their homes: -- Control temperature and humidity inside the house. Hot, humid houses are breeding grounds for dust mites and mold. Maintain temperature at 70 degrees Fahrenheit and relative humidity at 30 percent to 50 percent. -- Eliminate infestations. Control cockroaches and mice with inexpensive traps from the hardware store. --Eliminate mold. Close doors and windows during warmer weather and use air conditioning and dehumidifiers. -- Establish a weekly cleaning routine. Damp-mop wood or linoleum flooring, and vacuum carpeting. Use a vacuum cleaner with a small-particle or high-efficiency particulate air (HEPA) filter. -- No smoking. Don't allow smoking anywhere inside your house. About