Reduction of indoor particles concentration using re-circulating filtration units in Danish dwellings

Exposure to particulate matter has been shown to be associated with an increased risk of cardiovascular and respiratory diseases. The indoor environment contributes significantly to the total exposure to air pollution because of the many hours spent here, quantity of sources and low ventilation. This exposure can be reduced by using re-circulating filtration units, limiting the impact of outdoor pollution penetration, indoor emissions and decomposition of dust on heated surfaces.The objective of this study was to investigate whether reducing the indoor particulate concentration, by means of specially designed re-circulating particle filtration unit, will have positive impact on cardiovascular and respiratory health among elderly people. Two units were placed in each of 27 apartments situated in the Greater Copenhagen area, close to highly trafficked roads. In both, filtered and placebo periods, indoor air was recirculated through the unit during two weeks in a randomized and double blinded design. The measurements included concentration of PM2.5 and ultrafine particles (UPC), carbon dioxide, temperature and relative humidity, ventilation, air flow through the unit, allergen and fungal levels. Additional information was collected through questionnaires. Several medical tests were made, however the results are not included in this paper.Preliminary results showed significant decrease in PM2.5 concentration during the filtered period compared to placebo period. Likewise was UPC significantly lower during the filtered period. Moreover, UPC during placebo period showed similar values to measurements taken before the intervention. Further analysis including association with building characteristic as well as occupants’ behaviour will be presented.