title: A Case-Crossover Study of Heat Exposure and Injury Risk in Outdoor Agricultural Workers.
abstract: BACKGROUND
  Recent research suggests that heat exposure may increase the risk of traumatic injuries. Published heat-related epidemiological studies have relied upon exposure data from individual weather stations.
  
  
  OBJECTIVE
  To evaluate the association between heat exposure and traumatic injuries in outdoor agricultural workers exposed to ambient heat and internal heat generated by physical activity using modeled ambient exposure data.
  
  
  METHODS
  A case-crossover study using time-stratified referent selection among 12,213 outdoor agricultural workers with new Washington State Fund workers' compensation traumatic injury claims between 2000 and 2012 was conducted. Maximum daily Humidex exposures, derived from modeled meteorological data, were assigned to latitudes and longitudes of injury locations on injury and referent dates. Conditional logistic regression was used to estimate odds ratios of injury for a priori daily maximum Humidex categories.
  
  
  RESULTS
  The mean of within-stratum (injury day and corresponding referent days) standard deviations of daily maximum Humidex was 4.8. The traumatic injury odds ratio was 1.14 (95% confidence interval 1.06, 1.22), 1.15 (95% confidence interval 1.06, 1.25), and 1.10 (95% confidence interval 1.01, 1.20) for daily maximum Humidex of 25-29, 30-33, and ≥34, respectively, compared to < 25, adjusted for self-reported duration of employment. Stronger associations were observed during cherry harvest duties in the June and July time period, compared to all duties over the entire study period.
  
  
  CONCLUSIONS
  Agricultural workers laboring in warm conditions are at risk for heat-related traumatic injuries. Combined heat-related illness and injury prevention efforts should be considered in high-risk populations exposed to warm ambient conditions in the setting of physical exertion.
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.|Department of Medicine, University of Washington, Seattle, Washington, United States of America.
authors.forename: June T
authors.identifier: http://orcid.org/0000-0002-0761-1256
authors.initials: JT
authors.lastname: Spector
authors.affiliation: Safety and Health Assessment and Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, Olympia, Washington, United States of America.
authors.forename: David K
authors.initials: DK
authors.lastname: Bonauto
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.|Department of Biostatistics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Lianne
authors.initials: L
authors.lastname: Sheppard
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Tania
authors.initials: T
authors.lastname: Busch-Isaksen
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Miriam
authors.initials: M
authors.lastname: Calkins
authors.affiliation: Safety and Health Assessment and Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, Olympia, Washington, United States of America.
authors.forename: Darrin
authors.initials: D
authors.lastname: Adams
authors.affiliation: Department of Mathematics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Max
authors.initials: M
authors.lastname: Lieblich
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Fenske
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000383:Agriculture / Q000379:methods; D018592:Cross-Over Studies; D000067565:Farmers; D005260:Female; D018882:Heat Stress Disorders / Q000209:etiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014861:Washington; D014887:Weather; D055815:Young Adult