Fine dust is harmful to health. But universal limits and measurements do not exist. The WHO could change this by setting guidelines for a global definition of PM2.5. Adjusting the values would also imply more environmental zones.
A study by McGill University in Montreal examined the differences in the methods of data collection and processing of PM2.5 in 58 countries. The researchers found that the lack of a uniform definition of PM2.5 leads to strong differences in the measurement of the air pollutant. Comparison between measured PM2.5 levels in different countries is thus almost impossible. According to the researchers of the study, a harmonisation of the parameters for PM2.5 could only be achieved if the World Health Organisation (WHO) would set guidelines for a universal definition of PM2.5 based on the aerodynamic diameter and establish a common calculation method. The widely used average of PM2.5 values, as also used in the EU, also avoids the detection and control of pollution peaks.
The researchers also stressed that the levels set by countries are often far above those considered harmful by the WHO. According to EU standards for PM2.5, only 4-8 per cent of the EU population live in areas with excessive PM2.5 levels. The limit value is 25 micrograms per cubic metre (µg/m3). However, the WHO considers a value of only 10 µg/m3 as not harmful to health. Assuming this value, a full 74-78 per cent of the EU population lives in areas with harmful PM2.5 concentrations.
In China, the researchers found a two-tier system of standards, with less stringent levels in commercial areas than in residential areas. This means that people in residential areas can be better protected. However, people living near commercial areas are exposed to higher levels of particulate matter. In Canada, there are less stringent local, i.e. national, limits.
In Africa, standards are sometimes completely lacking. The German and European car export market also takes advantage of this. Many old diesel vehicles that are difficult to sell in this country are brought to Africa. The problem of bad air values is thus only shifted.
The study thus shows how ambivalent the definition of pollutants is. Indeed, the problem can only be solved by a uniform definition of the pollutant and its measurements. These could better identify and punish exceedances.
Moreover, if the limit values were to be adapted to those of the WHO in the future, for example in the EU, this could lead to significantly more environmental zones with stricter rules. Only in this way could the standards be reached quickly and the health of citizens be protected.