Environmental burden of disease resulting from long-term nitrogen dioxide exposure in Germany

Exposure to nitrogen dioxide (NO₂) is associated with an increased risk of cardiovascular, respiratory, and other diseases and health outcomes. Although NO₂ emissions have decreased in Germany, concentrations currently observed still pose a threat to population health. The aim of this study is to estimate the environmental burden of disease (EBD) resulting from long-term NO₂ exposure in Germany from 2010 to 2021.

To estimate the attributable disease burden, World Health Organization's EBD approach was used. We first conducted a systematic literature review to identify exposure-response functions (ERFs) which mathematically represent the association between NO₂ exposure and the health outcomes: asthma, chronic obstructive pulmonary disease (COPD), type 2 diabetes mellitus (T2DM), ischemic heart disease, lung cancer, stroke, and cardiovascular and respiratory mortality. Then, 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 mostly publicly available data. In a third step, using the ERFs and modelled ambient NO₂ exposure data, the fraction of the disease burden attributable to NO₂ exposure was estimated for each health outcome and year, stratified by sex.

The systematic review yielded recent ERFs for some exposure-outcome pairs, but not always for both mortality and morbidity outcomes. A full DALY calculation was possible for COPD and T2DM. For the other outcomes, either only YLL or YLD were calculated. Summing up the estimated YLD and YLL of all outcomes, the burden of disease due to NO₂ exposure in Germany decreased from 261,503 (95% UI 69,290-489,273) lost healthy years in 2010 to 100,032 (95% UI 24,558-191,715) in 2021.

Although the burden of disease attributable to NO₂ exposure decreased from 2010 to 2021, NO₂ still poses a threat to population health in Germany. While the current legal concentration limit was generally not exceeded in Germany in 2021, stricter new values proposed by WHO were frequently surpassed. When comparing the results to a previous assessment, it was obvious how strongly different input data impact the results. Transparent reporting of input data and discussing potential challenges when interpreting EBD results are critical.