What is the true impact of intensive farming on the pollution alarm in the Po Valley

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What is the true impact of intensive farming on the pollution alarm in the Po Valley

We spoke with the professor of Rural Construction Marcella Guarino to understand how intensive farming affects the production of PM 2.5. The particles are highly harmful to health and for several days have exceeded the threshold limit set by the World Health Organization.

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Interview with Marcella Guarino

Professor of Rural Construction in the Department of Environmental Sciences and Policies at the State University of Milan

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The Po Valley has turned red. It is one of the European areas with the worst levels of air pollution. On Saturday 18 February the maps of Copernicus, the air data monitoring project created in collaboration with the European Union, showed that the concentration of PM 2.5 reached 76 μg/m³ micrograms per cubic meter, the value limit is 25 μg/m³. They are microscopic particles present in the air that are highly harmful to health. According to ISPRA, the Higher Institute for Environmental Protection and Research, PM 2.5 particulate pollution is caused mainly by heating and intensive farming.

“The obsolete heating systems are certainly the main problem, but the excrement and sewage of animals which release ammonia into the atmosphere also have an impact”, Marcella Guarino , professor of Rural Constructions in the Department of Environmental Sciences and Policies, explained to Fanpage.it at the State University of Milan. Yet it is possible to reduce the environmental impact of intensive farming, “it would be enough to exploit the technology we already have available”, underlines Guarino, “we could trigger a virtuous process, we need to invest and give incentives to farmers to achieve this objective”.

Let's start with the latest data. According to Arpa Lombardia, on Saturday 17 February, fine particulate matter (PM 2.5), among the most dangerous substances, had an average daily concentration of 76 μg/m³, or more than three times the limit considered acceptable by the World Health Organization . How do intensive farming affect this figure?

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Secondary particulate matter, PM 2.5, is generated from ammonia produced by intensive farming, which, once released into the atmosphere, binds to nitrogen oxide generated by industrial pollution, heating or cars. However, when we talk about intensive farming we must consider various potentially polluting elements. First the building, the structure where the animals live, then the removal of the wastewater, because ammonia is contained in urine, and the storage, where the sewage is stored.

And which one has the greatest impact?

The real problem regarding the formation of secondary particulate matter is the distribution of the wastewater in the field. Also because the Lombardy region has decided that storage must be covered, so it no longer produces emissions. If we leave animal waste on the field it is a problem, unless it is buried.

In what sense do you bury?

There are machines for this purpose, imagine a tractor that drags a barrel, on the barrel there is a pipe that goes down into the ground and the sewage is released, then there is another part of the machine that covers this sewage with the earth that was raised. The emission is reduced to zero. The problem is totally eliminated.

Totally?

If we bury the sewage, the emission of ammonia from the wastewater is eliminated. This, however, is only half the problem.

What is the other 50% due to?

25% is due to conservation , every day the sewage leaves the stable and goes into a containment tank. There are also some virtuous cases. Many farmers have covered tanks to generate biogas, thus creating energy from a renewable source and eliminating emissions. Methane, nitrous oxide, ammonia, when sewage comes out after anaerobic digestion it no longer has any smell or gas.

The other 25% instead?

It comes from the structure, they are different depending on cattle, pigs and poultry. Since ammonia is contained in sewage , the better I clean the structure, the fewer emissions I will have. For example, scrapers can be placed at the exit, the air is conveyed by these large fans into a system that reduces ammonia emissions. This can be done for all forced ventilation farms, therefore poultry or pigs.

For cattle instead?

Dairy cattle actually have a very frequent floor cleaning system . Scrapers are used. If they clean well and do not spread sewage on the floor, emissions are low.

We are talking about intensive farming, but what are they and what characteristics do they have?

Intensive poultry and pig farms are those that comply with the integrated environmental authorization, therefore farms with more than 2,000 pigs or 40,000 places for poultry . For cattle farming there is no similar rule, so we are talking about farms with a high concentration of animals. But intensive farming pollutes less than extensive farming.

Please explain better.

In extensive farming the animals are outdoors. So if I have a cattle and I keep it in a closed environment I collect its excrement every time, but if the animal is in the countryside it lays its excrement and the ammonia goes into the environment.

But isn't it worse for the animals' health?

So, the real problem for animals is the limitation of fresh air . Animals in intensive farming suffer from respiratory gastrointestinal diseases precisely because they lack natural air exchange and, being in a confined space, they become infected. This happens to chickens and pigs, not cattle, because cattle live in a barn open on all four sides. If adequate systems are built the problem is solved.

Returning to PM 2.5, what is the process that transforms ammonia into fine particles?

Ammonia is produced by animals in the form of sewage , it goes into the atmosphere, where it binds to nitrogen oxides, which are produced by industrial activity, traffic and the heating of our homes. And ammonia plus nitrogen oxide form secondary particulate matter. However, I also want to say something else: luckily we have animal waste.

Because it fertilizes.

Sure. If we didn't have that we would have to use synthetic fertilizers , without it we wouldn't have crops.

And what is the balance?

It's difficult, there is technology that must help us.

How?

By undergrounding, making biogas and biomethane plants , creating a circular economy so that ammonia does not reach the atmosphere and instead is transformed into renewable energy. Not only that, but also by correctly distributing the wastewater in the field and reducing the air inside the structures.

So with technology could we get to zero impact farming?

Certain.

The city of Milan, together with the Po Valley, are always among the areas most exposed to pollution. Why?

The Po Valley is also called the “basin” . The Alps on one side, the Apennines on the other, we have no air exchange, but the pollution is mainly due to heating . So much so that we have this problem in winter, much less in spring and summer.

But there are also many farms in the Po Valley, it will have an impact in some way.

Of course they are there and they have an impact, but they are the cause of less than a third of secondary particulate matter.

So they are not the determining factor.

No. The problem is the heating and we struggle to digest this because we don't want to be in the cold, but the systems are obsolete, in Milan there is very little district heating. If we want to be honest, emissions from intensive farming are certainly higher during the summer period, because ammonia volatilizes in the heat . Then every activity pollutes and emissions from livestock farming must certainly also be reduced.

So what needs to be done to reduce the impact of factory farming?

Technology, as I was saying, is crucial, we can achieve zero impact, we need to invest and give incentives to farmers to achieve this goal.

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