gms | German Medical Science

Background: Exposure to nitrogen dioxide (NO₂) is associated with an increased risk for cardiovascular and respiratory diseases as well as other diseases and adverse health outcomes. Although NO₂ emissions have decreased steadily in Germany, the concentrations currently observed still mostly exceed the 2021 WHO air quality guideline value for long-term NO₂ exposure (10 µg/m³ on annual average). The aim of this study is to estimate the environmental burden of disease (EBD) due to long-term NO₂ exposure (above the WHO air quality guideline value) in Germany for the time series 2010 to 2021.

Methods: To estimate the attributable disease burden, the WHO EBD approach was used. First, we conducted a systematic literature review to identify suitable exposure-response functions (ERFs) which are a mathematical representation of the association between NO₂ exposure and the following health outcomes: asthma, chronic obstructive pulmonary disease (COPD), type 2 diabetes mellitus, ischemic heart disease, lung cancer, stroke, and for the grouping of diseases cardiovascular and respiratory mortality. In a second step, we estimated the years of life lost (YLL), years lived with disability (YLD) and, where possible, disability-adjusted life years (DALYs) due to these health outcomes in Germany using publicly available data. In a third step, using the identified ERFs and modelled ambient NO₂ exposure data, the fraction of the disease burden attributable to NO₂ exposure was calculated for each health outcome and year, stratified by sex.

Results: In the study period, a notable reduction in NO₂ exposure in Germany was observed. The systematic review yielded recent ERFs for most exposure-outcome pairs, but not always for both mortality and morbidity. Thus, a full DALY calculation was only possible for chronic obstructive pulmonary disease (COPD) and type 2 diabetes mellitus. For all other outcomes, either only YLL or YLD were calculated. Summing up the estimated YLD and YLL of all considered outcomes, the burden of disease due to long-term NO₂ exposure in Germany decreased from 261,503 (95 % UI 69,290-496,033) lost healthy years in 2010 to 100,032 (95 % UI 24,558- 195,489) in 2021. The largest share of lost healthy years was consistently due to type 2 diabetes mellitus and ischemic heart disease. Together, they accounted for over 50% of the disease burden attributable to NO₂ exposure in Germany.

Conclusions: Though the current EU legal limit value (of 40 µg/m³ on annual average) was mostly not exceeded and the burden of disease attributable to NO₂ exposure decreased from 2010 to 2021, ambient NO₂ still poses a threat to population health in Germany. When comparing the results to a previous NO₂ EBD study, it became apparent how strongly different input data can impact the results. Transparent reporting of input data and discussing potential challenges when interpreting EBD results are therefore crucial and should be mandatory when presenting EBD results.

The authors declare that they have no competing interests.

The authors declare that an ethics committee vote is not required.