Abstract
In epidemiological studies, both spatial and temporal variations in nitrogen dioxide (NO2) are a robust predictor of health risks. Compared to particulate matter, the experimental evidence for harmful effects at typical ambient concentrations is less extensive and not as clear for NO2. In the wake of the “Diesel emission scandal—Dieselgate”, the scientific basis of current limit values for ambient NO2 concentrations was attacked by industry lobbyists. It was argued that associations between NO2 levels and medical endpoints were not causal, as NO2 in older studies served as a proxy for aggressive particulate matter from incineration processes. With the introduction of particle filters in diesel cars, NO2 would have lost its meaning as a health indicator. Austria has a high percentage of diesel-powered cars (56%). If, indeed, associations between NO2 concentrations and health risks in previous studies were only due to older engines without a particle filter, we should expect a reduction in effect estimates over time as an increasing number of diesel cars on the roads were outfitted with particle filters. In previous time series studies from Vienna over shorter time intervals, we have demonstrated distributed lag effects over days up to two weeks and previous day effects of NO2 on total mortality. In a simplified model, we now assess the effect estimates for moving 5-year periods from the beginning of NO2 monitoring in Vienna (1987) until the year 2018 of same and previous day NO2 on total daily mortality. Contrary to industry claims of a spurious, no longer valid indicator function of NO2, effect estimates remained fairly stable, indicating an increase in total mortality of previous day NO2 by 0.52% (95% CI: 0.35–0.7%) per 10 µg/m3 change in NO2 concentration.
Highlights
The “fraud of Volkswagen” [1] has precipitated a discussion on the health impact of compression–ignition engine emissions from vehicles [2]
Data gaps from records of that station were filled with estimated values from linear regression based on data from another available station that was selected by maximal correlation
Upon inspection of iterative pairwise correlation, five stations were selected that were most strongly correlated with each other: Belgradplatz (BELG), Stefansplatz (STEF), Taborstrasse (TAB), Gaudenzdorf (GAU) and AKH (Table 1)
Summary
The “fraud of Volkswagen” [1] has precipitated a discussion on the health impact of compression–ignition engine emissions from vehicles [2]. The assumptions of Holland et al were strongly criticized by others [3]. While this discussion was still on-going, frequent exceedances of European air quality limit values of nitrogen dioxide (NO2 ) have triggered restrictions in many cities, for example, in Germany, for older diesel passenger cars. These measures were deemed “highly debatable” [4]. Public Health 2020, 17, 3733; doi:10.3390/ijerph17103733 www.mdpi.com/journal/ijerph
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More From: International Journal of Environmental Research and Public Health
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