1. Front door. Use a sturdy door-mat to scrape off dirt from shoes before it gets tracked in. Place the mat vertically instead of horizontally so that everyone who enters will have to step on it several times.
2. Lead paint. Over time, ingesting or inhaling dust and flakes from lead-based paint can cause brain damage. If you suspect that the paint in your home contains lead, have it tested. If it contains lead, don't remove it yourself but hire a specialist.
3. Household cleansers, pesticides, paints and solvents. To avoid potentially harmful chemicals, select detergent-based, biodegradable products on which the words "danger," "caution" or "flammable" do not appear.
4. Tightly closed windows. Keep a couple of windows open a crack year-round to let out fumes released by harsh cleaning products and chemical-laden furnishings, reduce mold-breeding moisture and lower levels of unsafe gases. If you have allergies, consider buying a HEPA (High Efficiency Particulate Arresting) air cleanser. For tobacco smoke, consider an air purifier that uses an activated carbon filter.
5. Pressed-wood products such as plywood and particle board. Construction materials, shelving, furniture, paneling, cabinets and other products made with these woods are assembled using urea-formaldehyde glues and adhesives, deemed probable human carcinogens. Formaldehyde irritates the respiratory tract and can cause or exacerbate allergic reactions. Opt for furniture and cabinets made with hardwood or metal.
6. Woodstoves or fireplaces. In addition to producing toxic and irritating combustion by-products, these may fill the air with dangerous particles of ash if you burn any¬thing other than hardwood. Burning damp firewood can release irritating mold spores.
7. Air conditioners. Both central air-conditioning units and window models can harbour mold, especially when they're not being used. Empty the water trays and change the filters often.