SHORT-LIVED chemicals formed when ozone reacts with traces of organic
pollutants could help explain the mystery of 鈥渟ick building syndrome鈥�, Danish
researchers suggest.
For many years, experts in occupational health have puzzled over symptoms
reported by office workers, including headache, nausea, fatigue and irritation
of the eyes, nose, throat and skin. In some cases, the culprit is clear: poor
ventilation, tobacco smoke or airborne bacteria. But in others, no suspect has
emerged.
Some scientists suspect that volatile organic compounds are to blame. VOCs
come from many sources, including wood, carpets, perfumes and even human breath.
But their concentrations in the air we breathe are usually much lower than those
shown to affect health. Now Peder Wolkoff and his colleagues at the National
Institute of Occupational Health in Copenhagen have found that, in combination
with ozone, one common VOC can produce eye and airway irritation at
concentrations much lower than would be needed if it were in isolation. Ozone
can enter buildings in photochemical smog from outside and is also produced by
equipment such as photocopiers.
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Wolkoff鈥檚 team measured the responses of 12 mice to a mixture of ozone and
alpha-pinene, which is given off by wood and pine-scented products. After 30
minutes, the animals鈥� breathing rate decreased on average by 30 per cent,
indicating airway irritation. The experimental concentrations, when adjusted to
account for the fact that mice are less sensitive to air pollutants than people,
are similar to those that might be experienced in an office building, Wolkoff
says.
When mice breathed air containing ozone and alpha-pinene separately, or the
end products formed after ozone and alpha-pinene have been left to react, their
response was minimal, the researchers report in a paper due to appear in the
journal Atmospheric Environment.
Wolkoff believes the culprits must be short-lived compounds formed by the
initial reaction between the VOC and ozone. He doesn鈥檛 yet know what these
irritants are. But they could be reactive radicals with lifetimes too fleeting
to detect with current techniques. That鈥檚 plausible, agrees Charles Wechsler, an
indoor air expert at Bell Communications Research in Red Bank, New Jersey: 鈥淚鈥檓
afraid there鈥檚 a lot that we鈥檙e missing right now.鈥�
Wolkoff鈥檚 work was funded by the Center for Indoor Air Research in Baltimore,
a body set up by the tobacco industry. Industry documents have revealed that it
has funded research into indoor pollution in an attempt to divert attention from
the dangers of passive smoking
(This Week, 2 May, p 22, and
16 May, p 4).
But Wolkoff says that his results won鈥檛 provide much comfort to tobacco firms.
鈥淭here are a whole group of VOCs that will react in the same way,鈥� he says. They
include a widely used lemon scent, chemicals from carpets and linoleum鈥攁nd
VOCs from tobacco smoke.
Other experts hope Wolkoff鈥檚 research will provoke further experiments on
interactions between different airborne pollutants. 鈥淥ur understanding of the
health effects of mixtures is not as good as it ought to be,鈥� says Leslie
Sparks, a chemical engineer with the US Environmental Protection Agency in
Washington DC.