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Ozone, photocopiers, asthma and the mite

Ozone is an unstable, colourless, odourless gas that occurs naturally in the atmosphere from solar radiation and electrical storms or from electrical equipment such as photocopiers in the indoor environment.
If exposure to ozone is high and prolonged it can irritate the eyes, nose, throat and the respiratory system and may cause headaches and nausea. As an irritant, ozone has the potential to trigger asthma attacks for those with established asthma. For patients with house dust mite related asthma, ozone can intensify allergic reactions to mite allergens. In the indoor environment some photocopiers produce ozone through the electrical charge used to place ink onto the paper. The average ozone emission from a photocopier is about 260 micrograms per minute although this can range from as little as 20 to well over 1000 micrograms per minute.

Concentrations of the gas should remain within acceptable limits if photocopiers are serviced regularly and are fitted with good quality ozone filters and adequate ventilation is maintained. Ozone readily degrades into oxygen. In the UK, provisions for ventilation in the workplace are laid out in the Workplace health, safety and welfare Regulations 1992. The Approved Code of Practice for these regulations (Ref. ISBN 0-11-886333-9) explains how this should be achieved.


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4. Ozone-induced bronchial epithelial cytokine expression differs between healthy and asthmatic subjects. J Bosson et al, 'Clinical and Experimental Allergy', 2003; 33: 777-782

5. Ozone Emissions from Laser Printers, 'UK Environmental Management', July 2000, HP Invent Hewlett-Packard Information Document.