For the Curious
Ozone, photocopiers, asthma & house dust mites (HDM)
Ozone is an unstable gas and health risk for patients with lung conditions because, like tobacco smoke, ozone can irritate sensitive or damaged lung tissue making symptoms worse. For house dust mite (HDM) allergic asthma patients avoidance of both mite and ozone exposure is recommended. Ozone can be a product of poorly maintained photocopiers or build up in offices with poor ventilation.
Ozone (O3) 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, especially if their asthma poorly controlled and triggered by house dust mite exposure.
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.
For patients with house dust mite related asthma, ozone can intensify allergic reactions to mite allergens. In a poorly ventilated office, ozone from photocopiers can make an allergic reaction to house dust mites worse because the change in the 'tone' of the lungs from ozone can build continuously for 6 hours and once established, persist for 24 hours. During this period an added allergic reactions, caused by mite exposure, can intensify symptoms.
People with asthma should understand this danger and avoid prolonged exposure to ozone in the workplace. Employers should make sure that all photocopiers are regularly serviced, in good working order and in office areas with excellent ventilation. This advice should be applied to home office space as well.
- Committee on the Medical Effects of Air Pollutions (COMEAP), 1996 Report, Annex C , Ayres J.
- Ozone airways and allergic airways disease: Krishna MT, Mudway I, Kelly FJ, Frew AJ, Holgate ST, Review, 'Clinical and Experimental Allergy', 1995, Vol. 25, pp 1150-1158
- House Dust Mite Der p 1 Downgrades Defenses of the Lung by Inactivating Elastase Inhibitors???, Brown A, et al, 'Am.J.Respir.Cell Mol. Biol.' 2003 Vol 29;pages 381 to 389
- Ozone-induced bronchial epithelial cytokine expression differs between healthy and asthmatic subjects. J Bosson et al, 'Clinical and Experimental Allergy', 2003; 33: 777-782
- Ozone Emissions from Laser Printers, UK Environmental Management, July 2000, HP Invent Hewlett-Packard Information Document.