Illustration of a tractor spreading slurry on its field, here in the Sarthe. Spreading is one of the sources generating ammonia in the air, promoting the creation of fine particles. - Gile Michel / SIPA

  • Air quality is poor in Brittany this weekend.
  • In this period of confinement where road traffic is limited, the concentration of fine particles can raise questions.
  • It is explained by the use of heating by individuals but also by agricultural activity, which generates ammonia in the air.

Air quality is poor in Brittany. According to data from the AirBreizh association responsible for surveillance, the index is 8 out of 10 across all Breton departments (7 in Morbihan) this Friday. The information and recommendation threshold has been exceeded and recommendations are to be followed. It is particularly good not to “overshoot” and therefore to limit physical activity and outdoor travel.

The situation should be the same on Saturday before an improvement is expected on Sunday. But how to explain the presence so concentrated of fine particles in the air when France is confined and that road traffic is almost nonexistent? Several factors are responsible for this deterioration: weather, heating and agricultural activity. In this period of fight against the coronavirus, pollution is a concern. In Italy, researchers have speculated that fine particles may have accelerated the spread of the virus. A study, however, disputed.

Air bulletin of 27/03/2020 for the Brittany region.
Find more information by going to https://t.co/SqqDOXOoux #QualiteAir #AASQA pic.twitter.com/YmPSzKJ6CP

- Air Breizh (@Air_Breizh) March 27, 2020

With the radiant spring that has taken hold in Brittany, weather conditions are unfavorable for the dispersion of pollutants in the atmosphere. "The absence of wind and the local high pressure conditions could favor the accumulation of dust", specifies Airbreizh. If the cold and the absence of wind participate in the concentration of particles, the origin of the appearance of these pollutants is to be found elsewhere.

Slurry applications release ammonia

The first reason probably comes from the fields. In this spring period, agricultural activity is intense in Brittany. The smells do not deceive. Many farmers spread their manure in the fields. This nitrogen supply technique used each spring is supposed to enrich the plants.

Air quality has never been better in Paris for 40 years https://t.co/5IbYvdxTNy

- 20 Minutes (@ 20Minutes) March 25, 2020

But we know that part of this nitrogen pollutes the water, an essential factor in the formation of the famous green algae. We know a little less that a good part also escapes into the air, generating ammonia, which promotes the creation of fine particles. "Nitrogen does not go completely into the soil, it volatilizes in the atmosphere and leads to the formation of ammonia", specifies Gaël Lefeuvre, director of Airbreizh. If livestock buildings release ammonia on a daily basis, it is mainly effluents such as slurry or the use of mineral fertilizers that generate these massive releases into the air in spring.

Residential heating and in particular wood heating are also an aggravating factor. In Brittany, the slightly higher presence of fireplaces and stoves may explain this deterioration, accentuated by the massive presence of residents in their homes, due to containment measures.

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