title: Relationship between ambient temperature and humidity and visits to mental health emergency departments in Québec.
abstract: OBJECTIVE
  This study examined whether the number of emergency department visits for "mental and psychosocial problems" varies with temperature or humidity.
  
  
  METHODS
  The number of visits in three geographic areas of Québec were examined as a function of temperature and humidity by using routinely collected May-September data for 1995-2007 (N=347,552 visits). Data for two age groups (under age 65 and age 65 and older) were examined. Incidence rate ratios for mean temperature and humidity were estimated by using Poisson regression and generalized additive models.
  
  
  RESULTS
  The number of visits tended to increase with increasing mean temperature. At 22.5 °C (72.5 °F) and 25 °C (77.0 °F), the number was usually significantly higher than average. Visits increased with humidity in the younger age group.
  
  
  CONCLUSIONS
  Results suggest increased use of emergency departments for mental and psychosocial problems with higher mean temperature and humidity, especially in metropolitan areas and in southern Québec. Climate change may make this effect increasingly important.
authors.affiliation: Department of Psychiatry, McGill University and McGill University Health Centre, B6-160, 1650 Cedar Ave, Montréal, Québec H3G 1A4, Canada. stephen.vida@mcgill.ca
authors.forename: Stephen
authors.initials: S
authors.lastname: Vida
authors.forename: Martin
authors.initials: M
authors.lastname: Durocher
authors.forename: Taha B M J
authors.initials: TB
authors.lastname: Ouarda
authors.forename: Pierre
authors.initials: P
authors.lastname: Gosselin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D004637:Emergency Services, Psychiatric / Q000706:statistics & numerical data*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D011792:Quebec; D014505:Urban Population; D055815:Young Adult