Particulate matter is the term used to describe various solid as well as liquid particles that accumulate in the air and do not immediately sink to the ground. The term encompasses both so-called primary emitters, those produced by combustion, and secondary emitters, those produced by chemical processes. A distinction is made between PM10 fine dust (Particulate Matter), which is 10 micrometers in size, and PM2.5, which is smaller in diameter. Due to the small particle size, particulate matter cannot be seen with the naked eye; only certain weather conditions make it visible in the form of a haze. Primary particulate matter is generated directly by emissions. These can be generated by vehicles, furnaces, and heating plants, as well as by certain industrial manufacturing facilities. Primarily, humans themselves bear a large share of the blame for particulate matter. However, erosion or brush fires can also generate it naturally. Agriculture, especially certain substances used in animal husbandry, provide secondary particulate matter.
Particulate matter pollution
The extent to which the body is damaged by particulate matter depends on how large the particles are, how deeply they penetrate the body, and how long a person is exposed to particulate matter. Although particulate matter can also be produced naturally, particulate pollution is primarily a man-made problem. Increasing road traffic in particular is causing pollution levels above the limit values, with not only gasoline combustion but also tire abrasion playing a role. Since the particles can be harmful to health in excessive concentrations, limit values for PM10 particles have been in force in Europe since 2005. The permissible daily value is 50 μg/m3 , and this may not be exceeded more than 35 times a year. The annual mean value is again 40 μg/m3. For PM2.5, the annual mean value has been 25 μg/m3 since 2008. Particularly in large cities, particulate matter levels are often above the limit due to heavy road traffic. Measurements by the Federal Environment Agency (UBA), for example, show that fine dust pollution in Stuttgart exceeded the limit value 95% of the time within the measurement period in 2011. The UBA also provides information on current pollution data for individual cities. In principle, however, particulate matter pollution in Germany has declined since 1990 due to the emission measures that have been introduced.
Health risks
Fine dust is characterized by its ability to remain in the air longer than other particles before settling to the ground. Therefore, the risk of ingesting the particles with the air we breathe is higher here. If the fine dust enters the body, however, it can trigger various health consequences. The extent to which the body is damaged by the particles depends on how large the particles are, how deeply they penetrate the body and how long a person is exposed to the fine dust. Basically, it is less important whether it is an aggressive chemical substance or dust particles alone, rather the size of the particle is decisive. The smaller the dust particle, the deeper it can penetrate the body, which means that it cannot usually be exhaled again. It is assumed that PM10 particles only settle in the nasal cavity, whereas PM2.5 particles migrate into the bronchi and alveoli. So-called ultrafine particles, in turn, can even settle deep in lung tissue or the bloodstream. Since the particles are absorbed through breathing, the respiratory tract is particularly at risk. In the short term, exposure to fine dust can lead to irritation of the mucous membranes and inflammation. The trachea and bronchi are particularly affected. These symptoms are comparable to allergic reactions, so that a so-called change of level can occur in the case of continuous exposure. In this case, the allergic reactions turn into chronic complaints – for the respiratory tract, this means that allergic asthma can ultimately develop. Patients who already suffer from asthma require a higher daily dosage of asthma medication when exposed to high levels of particulate matter. Since the particles can also enter the bloodstream via the alveoli, and the respiratory system is closely linked to the cardiovascular system, vascular and cardiac damage can also occur. The particles can lead to plaque buildup in the bloodstream, increasing the risk of thrombosis. Finally, the regulation of the autonomic nervous system itself may be affected, increasing the risk of heart attack.Studies by the World Health Organization (WHO) show that the risk of heart attack increases as air quality falls. The WHO estimates that in high traffic areas in Germany alone, particulate matter pollution shortens the life expectancy of residents by ten months. From the bloodstream, however, the particles can also reach other organs. The kidneys and liver in particular, as detoxification organs, are frequently affected. In principle, however, uptake via the skin or the gastrointestinal tract cannot be ruled out, so that health damage to the spleen or bone marrow is also conceivable. The so-called 19-dust study was also able to prove in rats that fine dust is carcinogenic. Dose-dependent exposure to fine dust produced lung tumors in the rats. It is assumed that the results can be applied in a similar way to humans. However, it has not yet been clarified whether fine dust has a direct carcinogenic effect, i.e. directly, or indirectly, via a decay product. It is particularly dangerous that no effect threshold can be determined for fine dust, but that it would not be harmful to health. If there are still limits for chemical substances, such as nitrogen dioxide, within which a health hazard for humans can be excluded, fine dust is harmful in any concentration. Infogram on the different lung diseases and their characteristics, anatomy and location. Click to enlarge. For example, a study by the Helmholtz Center in Munich showed that damage to health already occurs at levels below the EU limits; the risk of heart attack in particular was higher than expected (12-13% increased). Accordingly, it is not true that only a high, short-term exposure harms the body, especially a long-term exposure to a low concentration can be harmful to health. In fact, studies show that airborne particulate matter exposure is linearly related to health impairment.
Prevention and precaution
In order to reduce particulate matter pollution and thus health damage, guidelines for emission limits have existed in the EU for several years, and member states must adhere to them. At the same time, there are so-called environmental zones in many large cities, which may only be entered by vehicles with appropriate emission filters. It is assumed that environmental zones alone will reduce the annual average fine dust pollution by around 10 percent. However, experts generally assume that the traffic rate in Germany would have to be reduced by 60 to 80 percent in order not to exceed the daily maximum limits. Since this cannot be considered realistic in practice, there are repeated calls for personal initiative. Important factors here are: Using particulate filters, resorting to bicycles or public transportation instead of one’s own car, using cars with low fuel consumption, or limiting fuel consumption by driving at a low speed. Particularly in manufacturing plants in industry, but also nail studios or printers, particulate matter can also be generated. Prevention at the workplace is therefore just as necessary. This can be achieved through special extraction systems that are adapted to both the workplace and the pollutants produced. Where possible, workers should also make use of protective clothing such as a mouth guard.
