Improving indoor air quality in dental practices and certain hospital environments with stand-alone air purification systems.

The goal of this study was to investigate the effectiveness of stand-alone modular airpurification systems in improving air quality in dental practices and certain hospital andlaboratory environments. As air pollutant make-up and concentration may vary significantlyin different indoor enviromnents, the air cleaning technologies utilised should be optimisedfor the pollutants targeted in a particular environment. Reduction of mercury vapours andformaldehyde were examined because of their importance for indoor air quality in dentalpractices. In addition, particle and bacteria reduction was investigated as well as the removalof substances which are noticeable due to their strong odours. The air purifiers used in thestudy were configured to contain the most suitable air cleaning technology for each of theindoor environments. The systems use high-efficiency particulate air (HEPA/ULPA) filters,activated carbon-based filters with and without impregnation and/or activated alumina-basedfilters with impregnation. The maximum airflow of the systems ranges between 220 and 500m/h, depending on the filter configuration. The units were investigated under laboratory andsimulated field conditions to determine removal efficiencies for various substances. Highremoval efficiencies for mercury vapour, formaldehyde, particles and microorganisms couldbe observed. The elimination of strong odours (orange oil, cinnamon oil and menthol) isdifficult, if the source of the odour is not removed. The units effectiveness in dental practicesand in hospital treatment rooms will be analysed in follow-up studies including personal biomonitoringinvestigations. The data will facilitate the evaluation of the role that optimised airpurification systems can play in reducing pollutant exposure of medical personnel andpatients.