title: Association between Daily Hydrogen Sulfide Exposure and Incidence of Emergency Hospital Visits: A Population-Based Study.
abstract: The adverse health effects of high concentrations of hydrogen sulfide (H2S) exposure are well known, though the possible effects of low concentrations have not been thoroughly studied. The aim was to study short-term associations between modelled ambient low-level concentrations of intermittent hydrogen sulfide (H2S) and emergency hospital visits with heart diseases (HD), respiratory diseases, and stroke as primary diagnosis.
  
  
  
  The study is population-based, using data from patient-, and population-registers from the only acute care institution in the Reykjavik capital area, between 1 January, 2007 and 30 June, 2014. The study population was individuals (≥18yr) living in the Reykjavik capital area. The H2S emission originates from a geothermal power plant in the vicinity. A model was used to estimate H2S exposure in different sections of the area. A generalized linear model assuming Poisson distribution was used to investigate the association between emergency hospital visits and H2S exposure. Distributed lag models were adjusted for seasonality, gender, age, traffic zones, and other relevant factors. Lag days from 0 to 4 were considered.
  
  
  
  The total number of emergency hospital visits was 32961 with a mean age of 70 years. In fully adjusted un-stratified models, H2S concentrations exceeding 7.00μg/m3 were associated with increases in emergency hospital visits with HD as primary diagnosis at lag 0 risk ratio (RR): 1.067; 95% confidence interval (CI): 1.024-1.111, lag 2 RR: 1.049; 95%CI: 1.005-1.095, and lag 4 RR: 1.046; 95%CI: 1.004-1.089. Among males an association was found between H2S concentrations exceeding 7.00μg/m3, and HD at lag 0 RR: 1.087; 95%CI: 1.032-1.146 and lag 4 RR: 1080; 95%CI: 1.025-1.138; and among those 73 years and older at lag 0 RR: 1.075; 95%CI: 1.014-1.140 and lag 3 RR: 1.072; 95%CI: 1.009-1.139. No associations were found with other diseases.
  
  
  
  The study showed an association between emergency hospital visits with HD as primary diagnosis and same day H2S concentrations exceeding 7.00μg/m3, more pronounced among males and those 73 years and older than among females and younger individuals.
authors.affiliation: Centre of Public Health Sciences, University of Iceland, Stapi, v/Hringbraut, 101 Reykjavik, Iceland.
authors.forename: Ragnhildur Gudrun
authors.initials: RG
authors.lastname: Finnbjornsdottir
authors.affiliation: Centre of Public Health Sciences, University of Iceland, Stapi, v/Hringbraut, 101 Reykjavik, Iceland.|Occupational and Environmental Medicine, Department of Public Health and Clinical Medicine, Umeå University Hospital, 901 85 Umeå, Sweden.
authors.forename: Hanne Krage
authors.initials: HK
authors.lastname: Carlsen
authors.affiliation: Environment and Natural Resources, University of Iceland, Sturlugötu 7, 101 Reykjavik, Iceland.
authors.forename: Throstur
authors.initials: T
authors.lastname: Thorsteinsson
authors.affiliation: Occupational and Environmental Medicine, Department of Public Health and Clinical Medicine, Umeå University Hospital, 901 85 Umeå, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Oudin
authors.affiliation: Centre of Public Health Sciences, University of Iceland, Stapi, v/Hringbraut, 101 Reykjavik, Iceland.
authors.forename: Sigrun Helga
authors.initials: SH
authors.lastname: Lund
authors.affiliation: Faculty of Medicine, University of Iceland, Vatnsmýrarvegur 16 v/Landspítala, 101 Reykjavik, Iceland.|Department of Respiratory Medicine and Sleep, Landspitali University Hospital, Fossvogi, 108 Reykjavik, Iceland.
authors.forename: Thorarinn
authors.initials: T
authors.lastname: Gislason
authors.affiliation: Department of Preventive Medicine, University of Iceland, Stapi, v/Hringbraut, 101 Reykjavik, Iceland.
authors.forename: Vilhjalmur
authors.initials: V
authors.lastname: Rafnsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004636:Emergency Service, Hospital; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D006331:Heart Diseases / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D006862:Hydrogen Sulfide / Q000009:adverse effects* / Q000032:analysis; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D016014:Linear Models; D008171:Lung Diseases / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D011159:Population Surveillance; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology; D055815:Young Adult
chemical_list: D006862:Hydrogen Sulfide