Air pollution is often overlooked in home design, but if you're building or retrofitting a passive solar home, you cannot ignore it. Many traditional homes are leaky structures, allowing air to infiltrate through windows frames, doors, cracks in walls, and wherever else it can find a path. But passive solar homes rely on the house envelope being as airtight as possible. Obviously a 100% airtight home is a very bad, unhealthy idea, so ventilation must be provided – and ventilation can bring pollution with it.

Pollution inherent in the building

Many modern construction materials have toxic chemicals in them, some of which are released over time. This is known as "outgassing" and can go on for months after the home is finished, or even years.

Most of these toxic chemicals were built into materials in efforts to make home construction easier and more efficient. The most common among them is undoubtedly formaldehyde, which is used in various ways, the most prevalent of which is in the resin used in making oriented strand board (OSB). This board is tougher than standard wood, so it is thinner and more efficient to use. Unfortunately, formaldehyde can make the home's inhabitants hypersensitive over an extended period of time, eventually causing significant health deterioration.

In recent years, manufacturers have tried harder to reduce the number of potentially dangerous chemicals used in construction materials but, to be honest, they're a long way from perfect. Even today, toxic chemicals are used in ceiling tiles, upholstery, carpeting, drapery, particle board, plywood, stains, solvents, OSB, paint, and a whole host of other products.

Detergents and pesticides

Cleanliness is next to godliness, they say, so many of us house a whole army of cleaning products under our kitchen sink. But those products leak. It may only be miniscule amounts, but it's still there. Even worse, when you use those products they release an enormous number of potentially dangerous chemicals which linger in the air, poisoning you for hours after you've worked so hard to make your home "hygienic".

Pesticides also cause problems. They're a bit more obvious than detergents, since they're poisons used to repel ants, termites, flies, fleas, moths, and other creepy-crawlies, but even though they are supposed to contain inert, harmless materials, recent research has shown they may not be so benign for humans. The EPA estimates that 75% of American homes use at least one chemical pesticide in the home every year. Protecting your home from bugs might be damaging your health.

Some personal care products such as hair spray and nail polish also contain chemicals which can contaminate your air supply. The price of beauty may be higher than you thought. The same goes for certain hobbies, such as model-making and crafts that use solvents and paints.

And in an even crueler irony, air fresheners may not be so "fresh". Many of them contain the same chemicals as you would find in moth balls – but they release the chemicals freely and constantly in all your living spaces!

Natural and fossil fuels

All forms of fuel produce air