Sub-daily exposure to fine particulate matter and ambulance dispatches during wildfire seasons: a case-crossover study in British Columbia, Canada
Objectives: We aimed to assess the immediate and lagged relationship between sub-daily exposure to PM2:5 and acute health outcomes during wildﬁre seasons in British Columbia.
Methods: We used a time-stratiﬁed case-crossover study design to evaluate the association between modeled hourly PM2:5 and ambulance dispatches during wildﬁre seasons from 2010 to 2015. Distributed lag nonlinear models were used to estimate the lag-speciﬁc and cumulative odds ratios (ORs) at lags from 1 to 48 h. We examined the relationship for all dispatches and dispatches related to respiratory, circulatory, and diabetic conditions, identiﬁed by codes for ambulance dispatch (AD), paramedic assessment (PA) or hospital diagnosis (HD).
Results: Increased respiratory health outcomes were observed within 1 h of exposure to a 10-lg=m3 increase in PM2:5. The 48-h cumulative OR [95% conﬁdence interval (CI)] was 1.038 (1.009, 1.067) for the AD code Breathing Problems and 1.098 (1.013, 1.189) for PA code Asthma/COPD. The point estimates were elevated within 1 h for the PA code for Myocardial Infarction and HD codes for Ischemic Heart Disease, which had 24-h cumulative ORs of 1.104 (0.915, 1.331) and 1.069 (0.983, 1.162), respectively. The odds of Diabetic AD and PA codes increased over time to a cumulative 24-h OR of 1.075 (1.001, 1.153) and 1.104 (1.015, 1.202) respectively.
Conclusions: We found increased PM2:5 during wildﬁre seasons was associated with some respiratory and cardiovascular outcomes within 1 h following exposure, and its association with diabetic outcomes increased over time. Cumulative eﬀects were consistent with those reported elsewhere in the literature. These results warrant further investigation and may have implications for the appropriate time scale of public health actions.
Publication titleEnvironmental Health Perspectives
Department/SchoolMenzies Institute for Medical Research
PublisherUs Dept Health Human Sciences Public Health Science
Place of publicationNatl Inst Health, Natl Inst Environmental Health Sciences, Po Box 12233, Res Triangle Pk, USA, Nc, 27709-2233
Rights statementCopyright 2020 the authors. Reproduced with permission from Environmental Health Perspectives.