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Small particles cause big problems

Although better combustion systems and filter technology in industry and transport have greatly reduced air pollution caused by dust since the 1980s, the use of energy has remained a major source of particulate emissions. For instance, the increased burning of biomass in heating systems without filter systems is a particular cause of concern among environmental physicians.

The chemical composition and particle size play a decisive role in how dust affects human health. The World Health Organisation (WHO) points out that particulate matter reduces the average life expectancy in Germany by 10.2 months. Larger particles are deposited primarily in the nasopharyngeal area and the upper bronchi. Ultrafine particles (<100 nm) can even penetrate deep into the human respiratory tract and even sometimes into the bloodstream. On average they remain for a year in the alveoli and cause inflammation, DNA damage and vasoconstriction.

Therefore, environmental legislation makes a distinction in accordance with the particle size: for the coarsest fraction (PM10 to 10 μm), the daily limit is 50 μg/m3. This must not be exceeded by more than 35 times a year. The permissible annual mean is 40 μg/m3. Many large cities are currently struggling to comply with these provisions. For smaller particles (PM2.5), the average annual limit is 25 μg/m3 and, from 2020, 20 μg/m3. The WHO even only classifies concentrations below 10 μg/m3 as harmless!

The relationships between the emission of particles, the time they reside in the human body and their biological effects are the subject of intensive investigations. By means of epidemiological studies and animal testing, researchers are investigating systemic effects such as cardiovascular disease. They are also making increasing use of cell cultures. These enable them to verify changes in the metabolic processes in cells at a very early stage.

A study published in 2016 investigated the reasons for people dying in Hong Kong. Particulate matter in the metropolitan area increased the risk of death from cancer in the liver, pancreas or gallbladder by 35 per cent. With women, the risk of dying from breast cancer was even 80 per cent greater. The researchers therefore conclude that particulate matter has to be reduced in major cities worldwide as soon and as much as possible.

Projektinfo 06/2016:
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BINE-Projektinfo 06/2016
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