Longley, I. Olivares, G., Kachhara, A., Barraza, F.


Winter air quality and outdoor-indoor air exchange in 85 homes in New Zealand’s most polluted town


There is very little observational data on air quality in New Zealand homes. Anecdotally there are widely differing opinions on whether buildings provide protection from outdoor air pollution or not, and whether indoor or outdoor sources are more significant, especially on winter nights in wood-burning communities when ambient air quality standards are breeched. This is largely due to the cost and inconvenience of monitoring in homes and the large number of potential variables making it difficult to establish whether or not any home is representative of others.

Low-cost sensors now offer a solution allowing simultaneous indoor and outdoor monitoring in multiple homes. In winter 2019 a gridded network of outdoor PM sensors was deployed in Arrowtown, Otago. During the winter similar indoor sensors were deployed in 85 homes in 5 waves.

In 2019 Arrowtown recorded the highest number of exceedences of the PM10 standard of anywhere in the country. Our study revealed a wide variation in indoor air quality, infiltration of outdoor smoke and indoor sources. Infiltration was observed in nearly every home that had significant exposure to outdoor pollution indicating that no home provided full protection. Our results indicated the significance of pollutants becoming trapped and accumulated in more airtight homes especially overnight.