Improving Indoor Air Quality in Hospital Environments and Dental Practices with Modular Stand-Alone Air Cleaning Devices

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