BAD air in schools can affect pupils' and teachers' concentration and performance, research suggests.
Now a government-funded study is expected to provide much-needed information on the quality of the air in Britain's schools.
The cause of poor air is often mould growing in damp corners of a school. Some moulds give off highly toxic vapours which when inhaled can produce skin rashes, nausea and even liver damage and cancer. Airborne allergens such as mould spores and dust mites can also trigger attacks of asthma - Britain's most common long-term childhood illness, according to figures released this month by the National Asthma Campaign.
An audit by the charity found that one in five children has been diagnosed with asthma at some point and one in eight is currently receiving treatment for the condition.
Poor air quality in schools seems to be partly to blame for the rise in asthma rates, with two Swedish studies finding a link between concentrations of moulds, bacteria and cat allergens in schools and the number of pupils diagnosed with asthma. But there is little information about how far children are exposed to these pollutants in UK schools. The two-year study by the Building Research Establishment, which begins this autumn, will begin to provide this information.
Commissioned by the Department for Transport, Local Government and the Regions (DTLR) as part of a wider review of the effectiveness of building regulations, the study will measure ventilation and the main indoor pollutants in 10 modern primary schools in England.
If researchers do find high concentrations of pollutants in schools, the cause seems more likely to be shoddy construction that allows toxic fungi and other micro-organisms to breed under floors than poor ventilation.
"Undoubtedly there are problems in schools with ventilation and in extreme cases people might get tired quickly but mostly it's not a health issue," said Gary Raw, director of the Centre for Safety, Health and Environment at the Building Research Establishment.
"Where we get called in on individual trouble-shooting jobs we find more often than not that the problem has something to do with the floor or the ground beneath the school."
The establishment's troubleshooters are called in when schools complain about mysterious smells or ill-health.
Once the cause has been identified, it is usually straightforward to sort out - for example, by replacing a floor or decontaminating an area. But since schools tend to be fairly smelly anyway, it is often difficult to tell whether an odour comes from, say, sweaty feet or from something altogether nastier.
"I don't know how many schools across the country have air quality problems but based on our experience ... I suspect that there are more schools with problems than schools which recognise they have problems," said Dr Raw.
In the US the federal Environmental Protection Agency, which estimates that nearly half the nation's schools have poor indoor air quality, has produced voluntary guidelines for schools. The agency also publishes research on this area and has produced a tool kit to help schools identify and tackle air-quality problems.
No single government body in Britain is playing a similar role in relation to schools. The Department of the Environment, Food and Rural Affairs (Defra) is responsible for the national air quality strategy, which focuses on reducing outdoor pollution. Responsibility for indoor air quality is shared between several departments, including Health, Defra, and - when it comes to schools - both the DTLR and the Department for Education and Skills.
"It's not a satisfactory situation and we have been pressing for some time for somebody to take a lead on this," said a spokesman for the National Society for Clean Air and Environmental Protection.
Advice on the health effects of air pollutants is available from the Department of Health on www.doh.gov.uk and from the National Asthma Campaign on www.asthma.org.uk.
The website of the schools building and design unit at the Department for Education and Skills - www.teachernet.gov.uksustainabledevelopment - describes the Schools Environmental Assessment Method, a tool to help schools do their own environmental assessments.
Information on air quality in every local authority in the country can be found at www.aeat.co.uknetcenairqualaqmahome.html.
General background information on air quality is available on the National Society for Clean Air's website on www.nsca.org.uk.
The most comprehensive source of practical advice on dealing with air quality problems in schools, much of it relevant to the UK, is the US Environmental Protection Agency at www.epa.gov