To perfume the air or cover up unpleasant odours, many companies resort to air fresheners and deodorizers. Most air fresheners don't actually eliminate the source of the odour - they simply mask the bad smell with fragrance. Like other fragrance products, air fresheners are created with any of over 3000 synthetic chemical ingredients. Manufacturers are not required to list ingredients on the label, using instead the generic term "fragrance".

Deodorizers, on the other hand, may contain fragrance, but they usually also include ingredients that absorb odours, such as baking soda. They may also contain chemicals to kill bacteria or moulds that cause bad odours. Antimicrobial ingredients such as these are considered pesticides by the US Environmental Protection Agency.

Air fresheners and deodorizers that come in aerosol form frequently contain petrochemical propellants such as butane, isobutane and propane. The tiny droplets that are released into the air when you spray an aerosol don't just disappear. Though you can't really see them, they are easily inhaled into the lungs, where they can irritate airways. They are also highly flammable.

These propellants, along with the fragrance chemicals in air fresheners and deodorizers can irritate the skin, eyes or airways. For example, ethyl alcohol is a mild eye, skin and respiratory tract irritant. Limonene is an irritant and sensitizer, which means that repeated exposure can result in an allergy to the substance. Camphor, common in solid air fresheners, is another irritant capable of causing headaches, shortness of breath, weakness and central nervous system depression. Paradichlorobenzene (a pesticide also used in moth balls) is a known eye irritant.

Though one blast of an air freshener is unlikely to cause harm, multiple fragrances and frequent use can make indoor air quite polluted, especially if the area is poorly ventilated.

Even when the chemicals have fallen out of your breathing space, they land on the floor, carpeting, or furniture, leaving residues. Carpeting also tends to act like a "sink," where indoor air pollutants can collect.

Which would you rather use to clean your rooms?