The impact of wildfire smoke and temperature on traumatic worker injury claims, Oregon 2009–2018
This study examines the relationship between wildfire smoke, temperature, and traumatic worker injury claims in Oregon from 2009 to 2018. It finds that rising temperatures are linked to increased injury rates, particularly among agricultural and construction workers, while the presence of wildfire smoke did not show a significant association with injury rates.
College of Health researcher(s)
Abstract
Background and Aims
As average temperatures rise and wildfire events increase in the United States, outdoor workers may be at an increased risk of injury. Recent research suggests that heat exposure increases outdoor workers' risk of traumatic injuries, but co-exposures of heat and wildfire smoke have not been evaluated.
Methods
Oregon workers' compensation data from 2009 to 2018 were linked to satellite data by the date of injury to determine if acute heat (maximum Heat Index) and wildfire smoke (presence/absence) were associated with a traumatic injury. North American Industry Classification System (NAICS) codes were utilized to identify accepted, disabling injury claims from construction (NAICS 23) and agriculture, forestry, fishing, and hunting (NAICS 11). Claims from April to October were analyzed using negative binomial models to calculate incident rate ratios (IRR) by heat and wildfire exposure for All workers and specifically for Agricultural (Ag)/Construction workers.
Results
During the study period, 91,895 accepted, traumatic injury claims were analyzed. All workers had an injury IRR of 1.04 (95% confidence interval [CI]: 1.02–1.06) while Ag/Construction workers had an IRR of 1.11 (95% CI: 1.06–1.16) when wildfire smoke was present. When the maximum Heat Index was 75°F or greater, the IRR significantly increased as temperatures increased. When the maximum Heat Index was above 80–84°F, All workers had an IRR of 1.04 (95% CI: 1.01–1.06) while Ag/construction workers had an IRR of 1.14 (95% CI: 1.08–1.21) with risk increasing with increased temperatures. In joint models, heat remained associated with injury rates, but not wildfire smoke. No multiplicative interactions between exposures were observed.
Conclusion
Increasing temperature was associated with increased rates of traumatic injury claims in Oregon that were more pronounced in Ag/Construction workers. Future work should focus on further understanding these associations and effective injury prevention strategies.
Frequently Asked Questions: Wildfire Smoke, Temperature, and Worker Injuries
What was the primary focus of this research study?
This study investigated the relationship between acute exposure to high temperatures (measured by the maximum Heat Index) and the presence of wildfire smoke on the rates of traumatic worker injury claims in Oregon between 2009 and 2018. It specifically examined whether these environmental factors were associated with an increased risk of injuries for all workers and a subgroup of workers in the agriculture, forestry, fishing, and hunting (Ag) and construction sectors (Construction).
What were the key findings regarding the impact of temperature on worker injuries?
The study found a significant positive association between increasing maximum Heat Index and the rate of traumatic injury claims. This association was more pronounced for workers in the Ag/Construction sectors. Specifically, when the maximum Heat Index was 75°F or greater, the incidence rate ratio (IRR) for injuries significantly increased for both All workers and Ag/Construction workers, with the risk escalating at higher temperatures. For instance, when the Heat Index was 115-119°F, Ag/Construction workers had an IRR of 1.29, indicating a 29% increase in injury claims compared to days with a lower Heat Index (<65°F).
How did the presence of wildfire smoke affect worker injury claims?
The presence of wildfire smoke was found to be significantly associated with increased rates of traumatic injury claims for both All workers (IRR = 1.04) and Ag/Construction workers (IRR = 1.11) when analyzed as a single exposure. However, when both maximum Heat Index and wildfire smoke were considered in the same statistical model, the association between wildfire smoke and injury claims was no longer significant. This could be due to the correlation between wildfire smoke and high temperatures observed during the study period.
Did the study find any combined or interactive effects of heat and wildfire smoke on worker injuries?
The study did not find any statistically significant multiplicative interactions between the maximum Heat Index and the presence of wildfire smoke on the rates of traumatic injury claims for either All workers or Ag/Construction workers. This suggests that while both factors might independently contribute to injury risk, they did not appear to amplify each other's effects in a synergistic manner in this analysis.
Which worker groups were found to be most affected by high temperatures?
Workers in the agriculture, forestry, fishing, and hunting (Ag) and construction sectors (Construction) were found to be more susceptible to the increased risk of traumatic injuries at higher temperatures compared to the overall working population. The incidence rate ratios for injuries in these sectors consistently showed a greater increase as the maximum Heat Index rose above 75°F.
What data sources and methods were used in this research?
The study linked Oregon workers' compensation data from 2009 to 2018 with satellite-derived meteorological data (gridMET) to determine daily maximum Heat Index and satellite-based hazard mapping system (HMS) data to identify the presence of wildfire smoke. These data were then analyzed using negative binomial regression models to calculate incidence rate ratios, adjusting for factors like year, month, weekday, zip code, and estimated zip code employment. Employment estimates for different industry sectors at the zip code level were generated by combining county-level employment data from the Oregon Employment Department and zip code-level business pattern survey data from the U.S. Census Bureau.
What are the limitations of this study?
Several limitations were noted. The study used industry sectors (NAICS codes) to classify workers, which may not perfectly reflect who is working outdoors. Zip code-level employment estimates, while carefully generated, might not be entirely accurate. The meteorological data has a spatial resolution of approximately 4 km and may not capture finer-scale microclimates. The wildfire smoke data indicates presence but not the density or altitude of the smoke. Additionally, the correlation between heat and wildfire smoke could have influenced the results for smoke exposure. The study also lacked individual-level data on worker demographics, job tasks, work hours, and acclimatization.
What are the implications of these findings for worker safety and future research?
The findings highlight the need for occupational health policies and practices to protect outdoor workers, particularly in the Ag/Construction sectors, from the increasing risks associated with high temperatures. Given the anticipated rise in extreme heat and wildfire events due to climate change, these risks are likely to become more prevalent. The study suggests that even temperatures below the current Oregon OSHA high heat threshold (80°F Heat Index) may be associated with increased injury rates. Future research should focus on further understanding the mechanisms behind these associations, exploring the impact of wildfire smoke using alternative data and methods (including ground-level air quality monitors), and developing effective injury prevention strategies tailored to specific industries and occupations.