title: Solar radiation increases suicide rate after adjusting for other climate factors in South Korea.
abstract: OBJECTIVE
  Previous studies have indicated that suicide rates have significant seasonal variations. There is seasonal discordance between temperature and solar radiation due to the monsoon season in South Korea. We investigated the seasonality of suicide and assessed its association with climate variables in South Korea.
  
  
  METHODS
  Suicide rates were obtained from the National Statistical Office of South Korea, and climatic data were obtained from the Korea Meteorological Administration for the period of 1992-2010. We conducted analyses using a generalized additive model (GAM). First, we explored the seasonality of suicide and climate variables such as mean temperature, daily temperature range, solar radiation, and relative humidity. Next, we identified confounding climate variables associated with suicide rate. To estimate the adjusted effect of solar radiation on the suicide rate, we investigated the confounding variables using a multivariable GAM.
  
  
  RESULTS
  Suicide rate showed seasonality with a pattern similar to that of solar radiation. We found that the suicide rate increased 1.008 times when solar radiation increased by 1 MJ/m2after adjusting for other confounding climate factors (P < 0.001).
  
  
  CONCLUSIONS
  Solar radiation has a significant linear relationship with suicide after adjusting for region, other climate variables, and time trends.
authors.affiliation: Department of Biostatistics, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Jee
authors.affiliation: Department of Psychiatry, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Chul-Hyun
authors.initials: CH
authors.lastname: Cho
authors.affiliation: Department of Psychiatry, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Biostatistics, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Nari
authors.initials: N
authors.lastname: Choi
authors.affiliation: Department of Biostatistics, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Hyonggin
authors.initials: H
authors.lastname: An
authors.affiliation: Department of Psychiatry, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Heon-Jeong
authors.initials: HJ
authors.lastname: Lee
mesh_terms: D016001:Confidence Intervals; D005260:Female; D006801:Humans; D008297:Male; D011827:Radiation; D056910:Republic of Korea / Q000453:epidemiology; D012621:Seasons; D013405:Suicide / Q000523:psychology / Q000706:statistics & numerical data*
keywords: climate factor; seasonality; solar radiation; suicide