Jane Powers on fresh air
Two of the most potent cleansing agents are oxygen and ultraviolet light. In other words, fresh air and sunlight. This summer has given us plenty of oxygen, but it hasn't been overgenerous with high-quality ultraviolet light. So we'll return to that when we're feeling less gloomy, and concentrate on the fresh air and oxygen.
One of the bits of fresh air that does the cleaning is the extra oxygen atom that is found in O3, or ozone (as opposed to O2, or diatomic oxygen, the stuff we breathe). That extra atomic particle goes off and bonds with pollutants and disables them - and what's left over is breathable oxygen. Ozone is generated by thunderstorms, crashing waves and waterfalls. It also creates the heady, clean smell on clothes just in from the washing line.
Ozone has a more sinister side: it is formed by the action of sunlight on nitrous oxide (a pollutant emitted when hydrocarbons such as petrol, diesel and coal are burned), and when it accumulates in the air it can be irritating to the respiratory system and the eyes. Although ozone in the stratosphere is an excellent shield against solar radiation, and although small amounts naturally generated down here are beneficial, too much can be hazardous - which is why ozone machines (sold as air-cleaning devices) are not such a good idea.
A far easier, and low-tech, way of cleaning the air in our homes is simply to open the window. The indoor atmosphere, even in cities, can be more polluted than the air outside. It is, after all, outdoor air plus whatever we've added ourselves, through cooking, heating, cleaning, maintenance, bathing and various other everyday activities. Some building and decorating materials release contaminants continuously, as do various furnishings. A common volatile organic chemical, for example, is formaldehyde, which is released by some paints, carpets and upholstery, and by glues used in chipboard, plywood, MDF and other wood products.
The air inside houses may also be host to bacteria, mildew and other fungi, viruses, animal dander and cat saliva. Well-sealed modern homes keep all of them as snug as bugs in rugs (and if you've got those, too, in the form of house mites in carpets, they're happy as Larry in the warm and fuggy atmosphere). In short, the better the doors and windows are fitted, the less the air is changed, and the more the pollutants stay put.
Now if you don't mind, I'll leave it there, and go and open the window.