LAUSR

Abstract Background Global temperature and the frequency of extreme weather events are projected to increase and affect indoor exposure to outdoor particulate matter (PM); however, no studies have quantitatively examined the effect of climate change on particle infiltration and indoor PM exposure. Obective To quantify the relationship between future changes in ambient temperature and fine particle (PM 2.5 ) infiltration in the Greater Boston area. Methods We assembled a large database of outdoor and indoor PM 2.5 data from 340 homes, and used the indoor-outdoor sulfur ratio ( S r ) as a surrogate for PM 2.5 infiltration. We employed linear mixed-effects models to examine the relationship between S r and ambient temperature for all homes in the database and a subgroup of naturally ventilated homes. We used projected temperature data from 1981 to 2000 and 2046–2065 to predict future changes in S r . Results The summer-winter difference in S r was calculated to be 30% and 54% for all homes and in the naturally ventilated subgroup, respectively. The largest future difference in S r (21%) was linked to differences in prevalence of air conditioning. Furthermore, S r was predicted to increase by 7% for naturally ventilated homes and 2% for all homes in summer, corresponding to an average increase of 2–3 °C in future temperature. Conclusions We found that increases in future temperature due to climate change will be associated with increased PM 2.5 infiltration, particularly in summer. The predicted temperature-related changes in S r can be used to characterize future health risk due to elevated indoor PM 2.5 exposure through increased particle infiltration.