The Effect of Air Purification on the Indoor Air Quality in Habitable New Zealand Buildings

Particulate matter (PM) in indoor air, including fungal spores and bacteria, poses significant health risks, especially in poorly constructed and inadequately ventilated buildings that are prevalent in New Zealand. To maintain acceptable living conditions, there is a need to explore ways in which fungal and bacterial populations in habitable buildings can be reduced. In this study, six combinations of four different air treatments (HEPA filtration, UVGI, heating and dehumidification) were evaluated for their ability to reduce airborne fungal and bacterial populations in a stand‐alone ‘sleepout’ style building (ECR) in the Waikato region of New Zealand. Particulate matter (PM 2 . 5 ) sensors and settle plates were used to actively and passively monitor fungal and bacterial populations both inside and outside the ECR during treatments. HEPA filtration resulted in significantly lower fungal populations compared to no treatment; however, there was no observable reduction in bacterial populations from HEPA filtration alone. Overall, HEPA filtration in combination with other treatments was associated with reductions of both fungal and bacterial populations, and room temperature was shown to be a key driver of bacterial counts, but not fungal counts. Viruses were not examined in this study. As such, further studies may be conducted to assess viral loads, as well as optimising room temperatures and configurations to improve reductions of viable airborne bacteria.