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Health: Less fertilizer lowers mortality from air pollution


Use less fertilizer: reduce mortality due to fine dust pollution

Pollution of our environment is associated with a high health risk. Even small amounts of fine dust can be dangerous. The pollution with fine dust increases not only through traffic, but also through agricultural emissions. By reducing the use of fertilizer, according to researchers, mortality from air pollution could also be reduced.

Air pollution causes more and more deaths

According to the World Health Organization (WHO), air pollution is causing more and more deaths worldwide. Fine dust pollution primarily endangers the lungs, but the particles can also get into the heart via the bloodstream. German researchers have now shown in a study that reducing agricultural ammonia emissions could significantly reduce mortality from air pollution.

There are many sources for fine dust

Air pollution is a major health hazard. It is known that the tiny dust particles inhaled damage the lungs and significantly increase the risk of cancer, respiratory and cardiovascular diseases.

Various studies have shown that high levels of particulate matter significantly increase the risk of cardiovescular events such as heart attacks or strokes.

In addition, the risk of arteriosclerosis (hardening of the arteries) increases.

There are many sources of particulate matter - not just traffic, which is currently receiving a lot of attention.

A reduction in agricultural emissions could also significantly reduce the amount of harmful fine dust, as a study by researchers from the Max Planck Institute for Chemistry in Mainz shows.

Reduction of ammonia emissions

According to a message from the institute, the scientists calculated that the concentration of particulate matter in the atmosphere would decrease significantly, particularly in Europe and North America, by reducing ammonia emissions (NH3) from fertilization and animal husbandry.

If agricultural emissions were 50 percent lower, 250,000 deaths from air pollution worldwide could be avoided each year.

The results were published in the specialist magazine "Atmospheric Chemistry and Physics", a journal of the "European Geosciences Union".

Tiny particulate matter is particularly harmful to health

According to the WHO, fine dust particles with a diameter of less than 2.5 micrometers (PM2.5) are particularly harmful to health because the particles penetrate deep into the lungs and can cause cardiovascular and respiratory diseases.

In this way, they significantly reduce life expectancy in many areas of the world. According to the study “Global Burden of Disease”, air pollution ranks fifth among the risk factors for causes of death worldwide.

The study, which involves more than 1,800 scientists, quantifies deaths after illness, accidents and risk factors.

"The particulate matter pollution from traffic is currently being discussed in public, other sources such as agriculture are being neglected," said Jos Lelieveld, director of the atmospheric chemistry department at the Mainz Institute.

The fine dust emissions from motorized vehicles can make a decisive contribution to the local air pollution in metropolitan areas, but most fine dust (PM2.5) is only created by chemical processes in the atmosphere during wind transport.

"Therefore, the concentration of fine dust particles in the atmosphere could drop significantly if ammonia emissions were avoided in agriculture," says Lelieveld, whose research team has confirmed this with current calculations.

Death estimates increased significantly

In their previous study, Max Planck researchers indicated that 3.3 million people worldwide died prematurely from the effects of air pollution in 2010. In the meantime, the estimates for the past few years have risen significantly again.

The scientists emphasize that in many regions of the world, industry and transport are not the main sources of air pollution, as is generally assumed, but that, in addition to using fuels for heating and cooking, agriculture can play an important role.

The scientists identified the release of ammonia from animal husbandry and fertilization as the most important cause of air pollution, especially in large parts of Europe.

The nitrogen contained in ammonium is an important nutrient for plants. However, ammonia escapes into the atmosphere through the decomposition of liquid manure and through the fertilization of useful plants, where it reacts with other inorganic substances such as sulfuric and nitric acid to form ammonium sulfate and nitrate salts. This in turn creates fine dust particles.

50 percent less NH3 would prevent 250,000 deaths worldwide annually

In their current study, the scientists focused on four regions where air pollution limits are often exceeded: North America, Europe, South and East Asia.

Their calculations showed that a 50 percent reduction in all agricultural emissions worldwide would result in a decrease in around eight percent of the premature deaths caused by air pollution. That corresponds to a number of 250,000 people a year.

A complete stop of all ammonia emissions could, in theory, save 800,000 people worldwide from death from diseases caused by air pollution.

“The effect of ammonia reduction on fine dust formation is not linear. Efficient air improvement only starts at a certain reduction value. From this point on, the effect is exponential, ”explained Andrea Pozzer, group leader at the Max Planck Institute for Chemistry and lead author of the study.

A reduction in ammonia emissions of over 50 percent would therefore be very effective and desirable, Pozzer added.

Europe would particularly benefit

The scientists determined the mortality rates in two steps: First, using a model of atmospheric chemistry, they calculated how much less fine dust would result from lower ammonia concentrations.

According to this, a worldwide halving of emissions in Europe would result in 11.2 percent less PM2.5 particulate matter in the USA, 19 percent and 34 percent in China.

In Germany, the average level of particulate matter of this size in 2015 was around 14 micrograms per cubic meter of air, which would decrease to around 12.5 micrograms per cubic meter in the 50 percent reduction scenario of the Mainz researchers.

Using another model, which describes which health effects occur with which particulate matter exposure, the researchers then calculated the influence on the death rate from lung cancer, cardiovascular and respiratory diseases.

Europe in particular would benefit from a reduction in ammonia emissions and the resulting lower amount of fine dust: A Europe-wide NH3 reduction by 50 percent would reduce the PM2.5 mortality rate by almost 20 percent, so that around 50,000 deaths per year could be avoided.

In the United States, reducing ammonia on this scale would result in a 30 percent decrease in air pollution-related mortality, Andrea Pozzer and his colleagues calculated.

In contrast, the computer models showed minor improvements for East Asia with eight percent and only three percent for South Asia.

Based on the results, Jos Lelieveld concludes: "Emission regulations should set stricter limits for ammonia, particularly in North America and Europe, in order to effectively reduce fine dust concentrations."

Measures to reduce sulfur dioxide (SO2) and nitrogen oxides (NOx) are crucial for air pollution control, but should be supplemented by the reduction of ammonium from agriculture, which is also relatively easy to implement. (ad)

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