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Background: Exposure to fine particulate matter (PM_2:5) during wildfire seasons has been associated with adverse health outcomes. Previous studies have focused on daily exposure, but PM_2:5 levels in smoke events can vary considerably within 1 d.

Objectives: We aimed to assess the immediate and lagged relationship between sub-daily exposure to PM_2:5 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 PM_2:5 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 PM_2:5. 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 PM_2:5 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.

Item Type:	Refereed Article
Research Division:	Environmental Sciences
Research Group:	Pollution and contamination
Research Field:	Pollution and contamination not elsewhere classified
Objective Division:	Health
Objective Group:	Public health (excl. specific population health)
Objective Field:	Public health (excl. specific population health) not elsewhere classified
UTAS Author:	Johnston, FH (Professor Fay Johnston)
ID Code:	139930
Year Published:	2020
Web of Science® Times Cited:	19
Deposited By:	Menzies Institute for Medical Research
Deposited On:	2020-07-16
Last Modified:	2020-08-03
Downloads:	15 View Download Statistics