Indoor Air Quality Basics for Homeowners

Over my 37 year career in HVAC, I have been involved investigating many commercial and residential air quality problems. This article is intended to help homeowners to understand, and deal with the typical problems that are found in private homes.

Most “odors” come from gases or vapors. Typically, your home is loaded with such things, in the form of cleaning products, paint, lawn, garden and pool chemicals, and fuel for your power equipment like lawn mowers. Most are kept in cabinets under the sink, in the basement, or in an attached garage. All can release gases or vapors, which can range from annoying to dangerous. Some are lighter than air, others are heavier. For example, gasoline vapors can accumulate in a low area, and can explode, if a spark from any source occurs. Paint solvents like toluene and xylene can be toxic and also explosive in vapor form. Lawn insecticides and weedkillers may also be toxic and/or combustible.

Water-based paints are generally non-toxic, but especially in older houses, you can generate lead dust by sanding old paints. You can test suspect paint with a lead test kit from a home center or hardware store. Lacquers, varnishes and some stains may release toxic or combustible vapors as they dry, and de-natured alcohol, often used as a solvent, and lacquer thinner may also be toxic and/or combustible. “Exotic” paints, often used on automobiles or boats can be dangerous, both toxic and combustible. Never use these paints when there is a chance that their vapors may get into an occupied space, and always use proper respiratory protection! Paint strippers often contain strong concentrations of solvents or formic acid, and should never be used in an un-ventilated area, or stored in open containers, or around any ignition source. Paints and glues used on plastic scale models need adequate ventilation, and some are combustible. Never use around ignition sources, and always use proper respiratory protection; a respirator with a “Black” or “Yellow” cartridge. Some model paints are now water based, and non-toxic. Use them instead. Jewelry making exposes you to metal fumes, cleaner solvent vapors and solder. Make sure your hobby/craft area is adequately ventilated and free from ignition sources. Dispose of waste properly. Some woods, like mahogany and ebony, contain oils that certain people are allergic to. Dispose of sawdust and wood scraps.

Here are some easy solutions to these problems. A separate garden shed can go a long way toward improving the air quality in your home! Putting your lawn & garden chemicals, power equipment and fuel storage cans in there frees up garage space, limits evaporation and off-gassing, and a locked door keeps kids and pets away from possible harm. Make sure the shed has adequate ventilation! A wind-powered “cabbage-head” ventilator on the roof or one of the solar-powered fans makes for good ventilation. Gable vents, or a ridge vent also help, make sure there are some ground-level vents for air to circulate. Store gasoline only in approved gasoline cans; I can’t tell you how many times I have seen gasoline stored in milk jugs, washer fluid jugs or other flimsy, leak-prone containers! It’s a fire waiting to happen! Another dangerous practice that is all too common is to find gasoline powered equipment sitting right next to a water heater or furnace. One cup’s worth of gasoline vapor can turn a two-car garage to matchsticks!

If you have no room for a shed, plastic desk boxes can substitute, store your lawn chemicals and fuel cans in them. Be aware that certain solvents can damage the plastics used in such boxes. Propane tanks can be dangerous, never store them in a garage. Leaking propane is heavier than air, collects in low spots, and is violently explosive. Store them outdoors, away from any ignition source.

Recycle old obsolete propane tanks. “Empty” propane tanks AREN’T! Never leave the valve open, or expose them to direct sun. Mix lawn/garden chemicals outside, use gloves and eye protection. Don’t get them on your skin, change wet clothes, and wash up before eating, smoking or drinking. Store them in closed containers. FOLLOW DIRECTIONS!

Pool chemicals are hazardous. They can be corrosive, toxic and can interact with other common household chemicals. Pool chemicals should never be stored in an attached garage or in your basement, or with any other chemicals! A dry, ventilated storage site that is resistant to chemical damage should be used, and kept locked to keep kids and pets safe. Follow directions carefully. Use eye protection, gloves and respiratory protection when handling pool chemicals.

Your cleaning closet and your cabinet under the sink can be a source of IAQ problems, too. Dishwasher detergent, spray cleaners, scrubbing powders, ammonia all can cause problems, if not stored properly. Drain cleaners and oven cleaners are especially dangerous, and can cause severe chemical burns, blindness, or respiratory system damage. Mixing chlorine bleach and ammonia can be fatal…the chemical reaction produces phosgene gas, which killed thousands during World War 1. Don’t keep these two in the same cabinet! Check under the sink frequently for water leaks. Water initiates many IAQ problems, fix drips and leaks asap. Lock the cabinets and cleaning closet to protect kids and pets. Don’t leave wet cleaning rags in an enclosed space. Wash them promptly, or hang them outside to dry. Rags soaked with furniture oils/polish should be disposed of promptly. Never leave them in a confined space, they not only will off-gas odors, they can be subject to spontaneous combustion.

Cooking smoke and odors can be a problem, too. The best way to handle them is to exhaust them to the outside with a fan or a range hood. The “ductless” type of range hoods are mostly useless for removing smoke and odors. Their “grease filters” are little more than window screen, and the charcoal filters quickly get coated with grease, rendering them ineffective at removing odors. The fan will eventually deposit a layer of grease on the surrounding area. Don’t waste your money. Yes, a ducted fan may reduce cabinet space, you MUST have access to clean the ducts and grease may drip from the outside termination IF you don’t maintain it. They may be difficult and expensive to retrofit into your home. You must also replace the air exhausted by the range hood, and you must avoid putting your home under a negative pressure! That can allow deadly carbon monoxide to be drawn back into your home from the chimney.

Never put the laundry equipment in the same space as your furnace/boiler or water heater. Lint from the drier, detergent dust and chlorine bleach will seriously damage your heating equipment leading to premature failure and costly repairs.

Burning a few candles around the holidays won’t usually cause an IAQ problem. However, heavily scented, “jelly-jar” type candles may cause soot problems if used excessively.

Evaporating sticks, scented oil warmers, and other air “fresheners” contribute to IAQ problems, and are an indicator that something is wrong to a trained IAQ investigator. If you are covering up a bad odor with a pleasant one, something needs to be fixed. Pet areas may be a culprit. Open cat litter boxes must be emptied daily. If enclosed, and they have a filter, change it regularly. Wash your dog’s bedding frequently. Dispose of empty food cans properly. “Wet” pet food smells terrible! Clean dishes, and don’t leave it out all day!

Every year, people die needlessly from carbon monoxide poisoning. ANY burning fuel produces it. It is colorless, odorless and tasteless. It is insidious, people may never know they are being poisoned until it is too late. Small children and the elderly are especially susceptible. Make sure your chimney is functioning properly. Have a CSIA certified chimney sweep inspect it, and do any repairs needed. Your HVAC professional may also be qualified to check it out as well. Beware anyone who knocks on your door and says that they see you have a chimney problem. Unfortunately, there are many scam artists posing as chimney sweeps, use only a CSIA certified sweep.

Smoke detectors and carbon monoxide detectors are code requirements in some areas, and should be installed everywhere. Change batteries when you set your clocks back. Test them frequently!