In Germany there are regional driving bans on older diesel vehicles without SCR catalytic converters if the limit values for nitrogen dioxide (NO2) are exceeded. This has led to an intensive discussion about the effects of air pollutants on human health. The study shows that the data on the effects of NO2 and particulate matter (PM10 and PM2.5) are not sufficient to justify the driving bans.NO2 above 500 µg/m3 trigger temporary reactions in untreated asthmatics The German limit values (annual mean value 40 µg/m3) are mainly based on a meta-analysis of nine studies on indoor pollution, whereas only four studies measured NO2. In the large European Escape study of 2014, no influence of NO2 on mortality was found.NO2 is also no longer suitable as a surrogate parameter for other pollutants, as the proportion of particulate matter on the road is below 10 % since the introduction of particulate filters in diesel cars (approximately from 2000). Particulate matter mainly consists of swirling up mineral, organic soil substances and tyre abrasion and is most strongly influenced by weather phenomena, above all by solar radiation.The limit values for NO2 and particulate matter are calculated from epidemiological observational studies. There is usually a weak association between the concentration of the pollutants and numerous diseases and mortality. On the basis of epidemiological observational studies, hypotheses can be formulated. Repeated observational studies might suggest that some of the observed phenomena are not accidental. A causality cannot be deduced from this, since other factors besides NO2 and particulate matter might also be involved. To exclude these, intervention studies in the low-dose range and animal experiments are needed. Such data are almost completely missing or, as far as available, are all negative.A strong refutation of the hypothesis of the hazard of NO2 and particulate matter in the limit value range by inhalation smoking is never discussed. The smokers represent quasi an inhalation toxicological large-scale experiment. Cigarette smoke contains very high concentrations of particulate matter, nitrogen monoxide (NO) and NO2, which are surprisingly well tolerated by the organism. This is due to the fact that NO is a natural substance that occurs in the cells or even in the paranasal sinuses in sometimes very high concentrations (over 30,000 µg/m3). One of the degradation products of NO is NO2, which, by hydrolytic disproportionation, is converted into nitrate and nitrite. A part of NO2 is used for the synthesis of fatty acids.Cigarettes have a condensate of about 7 – 10 mg. Assuming a lifelong continuous exposure to particulate matter and NO2 in the limit concentrations, all smokers should have developed numerous diseases after a few days to months, which are attributed to particulate matter and NO2. The mortality rate should also be drastically higher; almost all smokers should have died after 1 pack year. The difference becomes even greater if one compares the proven toxicity and carcinogenicity of cigarette smoke with the fine dust on the road, which is usually much less dangerous.