Health effects associated with short-term exposure to hydrogen sulfide from geothermal power plants: a case-crossover study in the geothermal areas in Tuscany.

Abstract

Thirty-four geothermal power plants for the production of electricity are currently active in the geothermal areas in Tuscany. The present study aimed to investigate the association between short-term exposure to hydrogen sulfide (H2S) and acute health outcomes. This study used individual data on non-accidental, cardiovascular and respiratory mortality, urgent hospital admissions (HA) and emergency department (ED) visits for cardiorespiratory diseases occurring from 2000 to 2017. All cases were georeferenced and matched to daily H2S data, derived from 18 monitoring sites. A case-crossover design following the matched pair interval approach was applied and conditional logistic regression models were fitted to estimate odds ratios and their 90% confidence intervals, adjusting for a set of time-dependent variables, such as influenza epidemics, holidays and temperature. A total of 8054 deaths, 30,527 HA and 15,263 ED visits occurred. Mortality for non-accidental (OR = 1.11, 90% CI 1.02-1.22) and cardiovascular causes (OR = 1.22, 90% CI 1.03-1.44) were associated with an increase of 10µg/m3 of H2S daily levels only among men. Hospital admissions for respiratory diseases were positively associated with H2S exposure: OR = 1.11 (90% CI 1.00-1.22) among women. No associations were observed in ED visits analyses. In this case-crossover study in the Tuscan geothermal areas, short-term exposure to H2S was weakly associated with some mortality and morbidity outcomes. Our findings did not show a clear pattern as the results were not homogeneous between mortality and morbidity data or between men and women.