Some odours are harder to get rid of than others. Odours that come from organic sources—mould, food and decomposing matter—are most often sulphur-containing compounds hanging in the air or lurking in fabrics with fats or proteins. They may result from last night’s fish or the swim that your dog took at the park on Sunday, but most can be neutralised with one or more simple household chemicals.
Neutralise odours by eliminating their source. Find the source of the odour by using your nose or a black light (for organic stains). When you find the location, clean it with some dish washing soap and rinse with vinegar. The soap is a surfactant and breaks down surface tension, and vinegar is a mild acid that kills bacteria. Citric acid is another neutraliser that can wipe out bad smells like fish and onions. Or choose Simple Green or other biodegradable cleaners—anything that works as a surfactant to break up the grease or fat that holds the stinky compound together.
Neutralise musty odours by removing the moisture that carries them. Invest in a dehumidifier to take the excess moisture out of the air. Then fill a nylon stocking with plain clay cat litter, dried (used) coffee grounds or crushed plain charcoal and hang it in the room. All of these substances draw moisture in. The clay is fairly passive but the coffee grounds give off a pleasant odour of their own and the charcoal actually traps the particulate matter that carries the compounds that make up odours.
Houseplants consume carbon dioxide and exhale pure oxygen. Plant aromatic herbs and enlist their help to fight odour: the same enzymes that create the pungent aromas of many herbs interact with sulphide in odours to neutralise the smells. The mint family has provided odour-fighting scents for centuries; Spearmint and Wintergreen are aggressive growers and Lemon mint is a new variety that combines citrus and mint. Plant herbs near the kitchen door and cut mint for summer teas and bouquets in the kitchen to neutralise cooking smells. Basil is another aromatic herb that gives off aromatic scents when hung in bunches or kept in vases.
Use natural chemistry; many substances that are used in the odour absorbers sold commercially are available on the grocery or hardware store shelf. Use bicarbonate of soda (baking soda) to soak up smells in the refrigerator and in smokers’ ashtrays. Plain white vinegar vapours interact with cigarette smoke and animal odours. Plain barbecue charcoal or aquarium charcoal set in a dish will neutralise cooking and household odours. Household cures require gentle agitation every few days and replacement every few weeks, but a little experimentation may find a simple cure. All of these substances contain chemicals that oxidise compounds in odours, meaning that they produce new (non-smelly) compounds. A scrub of peroxide, baking soda and vinegar used on materials that smell of wood smoke, for example, will produce oxygen, water and a precipitate of soda ash—and no smoky smell.
If all else fails, invest a few dollars in an odour fighter like Fabreeze, Fresh Wave or Bad Air Sponge. Most of them combine a moisture absorbent material with plant oils or chemicals to kill the odours riding on the moisture brought in by the absorbent material. Use these products only as directed on the package.
Always clean before trying any neutralising tactic. Mold, decaying matter and bacteria will defeat any dehumidifier, chemical or absorbent. Bleach does not deodorise but it does kill germs and bacteria that cause odours. Use a dilute rinse on mould and mildew.
Do not keep any leftover solution of peroxide, baking soda and vinegar after use--these ingredients can react together in an explosive way.