What's In A Breath of Fresh Air?

Other factors to consider?

Ionizer manufacturers often state that their products are emulating the negatively charged atmosphere found in forests and by the sea. However, there is no hard evidence that the therapeutic effect of nature is caused by negative ions and skeptics claim that there could be other factors at work.

Scientists at the University of East Anglia have put the distinctive seashore smell down to dimethyl sulphide (DMS), a strong-smelling gas that is emitted by marine microbes. Their research also stresses that inhaling DMS, which is an irritant, is not necessarily healthy, although it is usually present in such low concentrations that it isn’t particularly harmful either.

In Japan, many people seem to believe that ionizers provide health benefits. Many personal products like toothbrushes, washing machines and refrigerators have been adapted to emit ions. Forest bathing, or shinrinyoku, is a popular Japanese therapy and involves being guided through a forest and taking deep breaths of the air, which is rich with particles emitted by the trees. However, forest bathers mostly agree that the improvement in their wellbeing is caused by breathing in phytoncides released by the trees. Phytoncides are organic compounds that are emitted from some plants to prevent them from rotting or being eaten by certain animals or insects.

Although the effect of ions on human health is still being debated, most people would agree that breathing fresh, clean air is good for one’s health. Polluted city air and dusty indoor locations are unpleasant for most people, especially those with asthma and other respiratory conditions. Whether this has to do with ions in the air or not, there is no doubt that spending time out in nature contributes to a healthy lifestyle.

Air ionisers wipe out hospital infections
http://www.newscientist.com/article.ns?id=dn3228

Dawn machine 'beats winter blues'
http://news.bbc.co.uk/1/hi/health/6233421.stm