In a study, the National Center for Healthy Housing found that 35 million homes have at least one health or safety hazard, and there are more than 6 million units in substandard condition. Housing conditions play a critical role in public health.

By following seven basic principles, you can create a healthier home.

1. Keep your home dry.

Mites, molds and other allergens can be controlled by managing the indoor environment, specifically keeping humidity at less than 50 percent, according to the Iowa Department of Public Health.

Some ways to limit the growth of mold and mildew in your home include keeping windows open when outside conditions allow and using fans to increase ventilation.

Also, the Green & Healthy Homes Initiative, formerly known as the Coalition to End Childhood Lead Poisoning, suggests checking the plumbing for leaks and preventing water from entering your home through proper drainage and roof maintenance.

2. Keep your home clean.

Clean homes help reduce pest infestations and exposure to contaminants.

Reduce clutter in your home, vacuum and dust regularly, clean or replace air filters in your heating and cooling system and follow directions on cleaning products and storing them safely.

Read labels on cleaning products or create your own solutions from such household items as vinegar or baking soda to wipe floors, wash windows and scrub toilets.

3. Keep your home pest-free.

Recent studies show a relationship between exposure to mice and cockroaches and asthma episodes in children.

You can reduce the number of pests that get into your home by eliminating outdoor debris, sealing cracks and holes, getting rid of standing water and keeping weeds and tree branches cut back from the house.

4. Keep your home safe.

The majority of injuries among children occur in the home, according to U.S. Department of Housing and Urban Development. Falls are the most frequent cause of residential injuries to children, followed by injuries from objects in the home, burns and poisonings.

The Green & Healthy Homes Initiative suggests wiping up spills quickly, keeping fire extinguishers on hand, securing loose rugs, properly storing food, keeping children away from open windows and keeping their play areas free from hard surfaces and sharp objects.

5. Keep your home contaminant-free.

Chemical exposures include lead, radon, pesticides, volatile organic compounds and cigarette smoke.

The Environmental Protection Agency estimates that secondhand smoke is responsible for about 3,000 lung cancer deaths each year among nonsmokers in the U.S. About 800 of these are estimated to be from exposure to secondhand smoke at home, and 2,200 deaths are from exposure in work or social situations.

To reduce risk of contaminants, go smoke-free, have you home tested for radon, install a carbon monoxide detector and remove deteriorated paint in homes built before 1978.

6. Keep your home ventilated.

Studies show that increasing the fresh air supply in a home improves respiratory health.

7. Keep your home maintained.

Poorly maintained homes are at risk for moisture and pest problems, according to HUD. The Healthy Homes Maintenance Checklist highlights 65 items to examine inside and outside the home, from cleaning gutters and appliances to checking electrical equipment and dryer vents.