Indoor air quality, that is. It’s not a number, but when your indoor air isn’t good, it adds up to uncomfortable occupants and possibly health issues.
Ever overcooked something? And then had to field the “What’s burning?” question from everyone who enters the house all evening? This illustrates how contaminants can linger inside your home. But many contaminants are odorless and go undetected by the human nose. In addition, we readily assimilate most smells anyway, so your nose isn't a very reliable indicator of poor indoor air quality.
Keeping the Air Clean
Good ventilation is a prerequisite for healthy indoor air. Without proper ventilation everyday activities like cooking (especially with gas); showering; and even breathing often make your indoor air more polluted than the air outdoors. New carpeting and fresh paint can make it worse. Your house will always require a certain ventilation rate, but you can minimize the need for ventilation by controlling and reducing the contaminants generated within your home, and by installing some sort of an air treatment system.
Ventilation
Your home should have a minimum ventilation rate of 0.35 air changes/hour [Link to glossary], which means that 35% of the air in your home should be replaced by outside air every hour. In most older homes, the normal leakage through cracks, spaces and penetrations in outside walls and around doors and windows takes care of needed ventilation—and then some (link to page on air sealing). Newer homes are built tighter for energy efficiency, and some type of mechanical ventilation must usually be incorporated into the HVAC (heating, ventilating and air conditioning) system to achieve this ventilation rate.
Minimizing Indoor Pollution
Several common products and practices reduce the quality of your indoor air. Here are several, including some identified by Leeann Sagula of BBEI in the Sept./Oct. 2004 issue of eco-structure magazine.
- Air fresheners, especially oil-based fresheners that plug into outlets, contain known or suspected neurotoxins. Asthmatics may suffer attacks in homes with air fresheners.
- Candles, while good for a romantic atmosphere, produce black soot that accumulates on ceiling and carpet edges -- and on occupants' lungs.
- New carpeting, paints and varnishes (link to Green Finish Materials piece), if not chosen properly, generate significant amounts of volatile organic compounds (VOCs), which are chemical compounds that evaporate readily, can be toxic, and contribute to poor indoor air quality. Ask for low-VOC paints and other coatings. The Carpet and Rug Institute's (CRI) "Green Label" testing and labeling program identifies carpet products that are truly low-VOC. You can find these products on the CRI Web site.
- Cars, gasoline, paint and other chemicals generate toxic gasses. When these are stored in garages, especially attached garages, they can leak into your home. Garages should be well ventilated, preferably with an exhaust fan. Store chemicals, fertilizers and gasoline in an outside shed as far away as possible from home entryways.
- Pesticides and chemicals applied outside your home can be tracked into your home and can also come in through open windows. Use natural methods to control pests, fertilize lawns and gardens, and kill weeds. Gas-powered lawn mowers are notoriously polluting, and that exhaust gets into your house through open windows. Find out how to get better, healthier lawns (link to green lawn story) with less effort, less expense and less mowing.
Your HVAC inlet should always be properly filtered. A good filter will minimize the dust, pollen and other contaminants that are introduced into your home. Normal filters remove only dust and some pollens. HEPA filters do a much better job, and some are equipped with media that also filter selected chemicals.