Hydrogen sulfide and particle matter levels associated with increased dispensing of anti-asthma drugs in Iceland's capital

BackgroundAir pollutants in Iceland's capital area include hydrogen sulfide (H2S) emissions from geothermal power plants, particle pollution (PM10) and traffic-related pollutants. Respiratory health effects of exposure to PM and traffic pollutants are well documented, yet this is one of the first studies to investigate short-term health effects of ambient H2S exposure.ObjectivesThe aim of this study was to investigate the associations between daily ambient levels of H2S, PM10, nitrogen dioxide (NO2) and ozone (O3), and the use of drugs for obstructive pulmonary diseases in adults in Iceland's capital area.MethodsThe study period was 8 March 2006 to 31 December 2009. We used log-linear Poisson generalized additive regression models with cubic splines to estimate relative risks of individually dispensed drugs by air pollution levels. A three-day moving average of the exposure variables gave the best fit to the data. Final models included significant covariates adjusting for climate and influenza epidemics, as well as time-dependent variables.ResultsThe three-day moving average of H2S and PM10 levels were positively associated with the number of individuals who were dispensed drugs at lag 3–5, corresponding to a 2.0% (95% confidence interval [CI] 0.4, 3.6) and 0.9% (95% CI 0.1, 1.8) per 10 μg/m3 pollutant concentration increase, respectively.ConclusionOur findings indicated that intermittent increases in levels of particle matter from traffic and natural sources and ambient H2S levels were weakly associated with increased dispensing of drugs for obstructive pulmonary disease in Iceland's capital area. These weak associations could be confounded by unevaluated variables hence further studies are needed.

► Presciption asthma drug sales are a proxy for respiratory health in a population.
► The Icelandic Medicines Registry holds individual-level data on dispensing.
► A regression modeled the daily dispensings as a function of air pollutant levels.
► Particle matter and hydrogen sulfide were positively associated with drug sales.