Air quality analysis
Better air – A worthwhile objective
Clean air is a fundamental commodity. Unfortunately however, air pollutant concentrations are increasing continuously. Recommendations, on which pollutant levels are hazardous to health and should not be exceeded, vary…
The German limit value recommendations for nitrogen oxide (NO2) adopt the WHO (World Health Organization) recommendations and the evaluation of the Air Pollution Prevention Commission ("Kommission Reinhaltung der Luft" (KRdL)) of the VDI and DIN. However, both recommendations diverge significantly: The WHO recommends an annual median of 40g/m³ and a short-term value of 200g/m³ under consideration of the current literature, while the KRdL indicates a long-term load limit of 20g/m³ and a 24-hours value of 40g/m³.
What is the reason for such differences in the evaluation of the load limit for the human organism? The Research Association for Automotive Technology (Forschungsvereinigung Automobiltechnik (FAT)) addressed this question and entrusted research centres with the task of performing an evidence-oriented comparison of the recommendations based on the respective applied literature in order to explain these differences. The analyses showed that the different recommendations are not based on different scientific results, but rather on the WHO and KRdL having different protection objectives.
The KRdL focuses on the perspective of the preventive healthcare to justify its low recommendations as compared to the WHO. The WHO in turn, notes that the observed effects might not only be caused by NO2 but also by other correlating air pollutants – and sticks to its original recommendation of 40g/m³ as an annual median value.
Due to the continuous development of environment-medical findings, the FAT ordered further studies. A total of 214 international original works concerning NO2 were performed between 2003 and 2006. 111 studies thereof were highly health-relevant and were evaluated with a revised criteria list by the Commission on Radiological Protection.
The evidence of the most recent scientific findings on the health risks of NO2 remains quite limited. Even under consideration of the results for particularly sensible population groups, like e.g. children, aged people, asthmatics, etc. no highly evident relationships were identified. The causal connection between NO2 concentrations below 40g/m³ and health impacts remains uncertain. Even the recent topical literature fails to provide an evidence of the toxic effect of NO2 concentrations below 200g/m³ on the human lung. This significantly extended analysis of the available data provides no scientific justification for lower air quality values than recommended by the WHO in 2003.
