Environmental pollution fine dust
Current limits for particulate matter in the air are based on the mass and size of the particles. Although the mass of the dust is important for health, its composition is also important. Empa researchers have now analyzed the harmful potential of fine dust in Switzerland and China.
Anyone who is suddenly shaken by an uncontrollable coughing fit on a gloomy day may be suffering from the consequences of too much particulate matter in the air. Respiratory problems, circulatory diseases or even lung cancer can be triggered by the tiny particles. Suspended particulate matter caused by humans contains, for example, soot, metals and synthetic nanoparticles. In order to control air quality more strictly, since June 1, 2018, Switzerland has been subject to the new, stricter Ordinance on Air Pollution Control (LRV).
In addition to PM10, this sets a second limit value, PM2.5, for even finer suspended particles. Both values are based on the mass of particles up to a certain size limit - i.e. 10 and 2.5 micrometers in diameter respectively. In a recent study, researchers at Empa have now shown that even further values allow important statements to be made about the damaging potential of particulate matter.
Air samples from China and Switzerland
Jing Wang and his team from the Empa "Advanced Analytical Technologies" Laboratory investigated air samples from Switzerland and China. As expected, the air quality of the Beijing metropolis came out worse than the samples from Switzerland. With their detailed analyses, however, the researchers also uncovered that the composition of fine dust differs greatly. "If you look at the so-called oxidative potential of the particulate matter, for example, the effect of comparable particle pollution was greater and therefore more consequential in some Swiss samples than in China," Wang says. The oxidative potential is one of the measures of the harmful effect of fine dust, since aggressive substances trigger oxidative stress and immune defense reactions in the body.
Metals such as cadmium and arsenic or soot particles, for example, are involved in these health-damaging properties of suspended particles. In China, large quantities of ultrafine arsenic particles indicated a health risk in the air. Samples from the Zurich suburb of Dübendorf, on the other hand, contained a striking number of iron particles in the 10-micrometer range. "The iron particles originate from abrasion from the nearby railroad line," the researcher said. Together with copper and manganese, the iron dust in the Dübendorf air sample contributed to the oxidative potential of the samples.
Another Swiss value caught the eye of the Empa researchers: The air sample from a Swiss farm, for example, performed worse than that from a busy street in the middle of Beijing, at least as far as the contamination with certain bacterial products was concerned. It is well known that endotoxins of this kind are found in high concentrations in the air around cows and other animals. However, especially for people with a weakened immune system, the biological suspended matter can pose a health risk. Especially the ultrafine suspended particles from the farm were contaminated with bacterial endotoxins.
"The impact of particulate matter on air quality and health cannot be assessed by the mass of inhalable particles alone," says the analyst. "But if you know the composition of particulate matter, you can implement regionally appropriate health protection." Otherwise, he says, one runs the risk of underestimating regional particulate pollution or taking measures that do not reduce health risks. Jing Wang and his team are now working on further foundations for more comprehensive particulate matter analyses. The aim is to make it easier to identify hazardous components and prevent health risks with optimized strategies.
More about the above topic and individual measuring ranges can be found at here
