Assessment of the indoor air quality in copy centres at Aveiro, Portugal

This study presents continuous measurements of size-segregated particulate matter, total volatile organic compounds, ozone, formaldehyde, comfort parameters (temperature and relative humidity), CO and CO2 at two copy centres (A and B) in Aveiro, Portugal. PM10 samples collected with low-volume samplers were used to determine the carbonaceous content (organic and elemental carbon) by a thermo-optical technique. Mean PM10 levels of 55.8 +/- 7.50 mu g m(-3) and 51.3 +/- 9.35 mu g m(-3) were obtained in copy centres A and B, respectively. The 24-h indoor PM10 concentration at both copy centres exceeded the protection limit established by the Portuguese legislation. Around 60 % of the PM10 were composed of particles with sizes below 2.5 mu m. On average, organic carbon accounted for 27.6 % (copy centre A) and 18.6 % (copy centre B) of the PM10 mass indoors, whereas a lower mass fraction of 11.5 % was found for both outdoor spaces. The much higher indoor levels of organic carbon suggest significant contribution by indoor sources. The ozone level increased in both copy centres when the photocopiers started to work. Mean ozone levels (0.055 +/- 0.005 and 0.048 +/- 0.006 ppm in copy centres A and B, respectively) during business hours may exceed the standard recommended for workplaces (0.05 ppm), representing a cause of possible adverse health effects on employees. The indoor-to-outdoor ozone concentration ratios were greater than 1 in both centres, indicating an important contribution of indoor sources. Formaldehyde levels remained always below the World Health Organisation guideline for indoor air (0.1 mg m(-3)). Total concentrations of volatile organic compounds were also relatively low, in general ranging from around 190 to 300 ppb. The indoor-to-outdoor concentration ratios were in the range between 0.70 and 0.76. Results showed that operation of laser printers can lead to high particulate matter and ozone concentration indoors. Pollutants associated with printing equipment have potential to cause adverse health effects if exposures are sufficiently high. Precautions should be taken to minimise the risks of exposed workers.