The combination of nitrogen and oxygen in the air leads to chemical compounds of various forms grouped under the term NOx. Regularly measured, nitric oxide (NO) and nitrogen dioxide (NO2) are emitted during combustion. NO2 is derived from the oxidation of NO. The main sources are transportation (road, sea and river transport), industry, agriculture and power production.NO2 also occurs inside premises where gas appliances such as gas cookers, water heaters, etc. operate.
The origins of the majority of the NO2 are from major industrial complexes (Gonfreville, Harfleur, Oudalle, Gravenchon, Lillebonne, Grand-Quevilly, Petit-Couronne, Grand-Couronne, …) and from major cities (Caen, Le Havre, Rouen, Evreux).
The majority of the NO2 comes from the industrial sector (45 %) and transportation (44 %). The emissions from sea transport represent 8 % of transportation.
NO2 is an irritant gas irritant for the airways. In asthmatics, it increases the frequency and severity of crises. In children, it makes lung infections more likely.
Effects on the environment
NO2 participates in the phenomena of acid rain, the formation of ground level ozone where it is one of the precursors, attacks on the stratospheric ozone layer, and participates in the greenhouse effect.
The reference standards
Information and recommendation threshold for sensitive individuals
Alert warning threshold for the general population
200 µg/m3 hourly average
400 µg/m3 hourly average
Limit values for the protection of human health
200 µg/m3 hourly average not to be exceeded more than 18 hours per year
Atmo Normandie is an association for monitoring air quality.It belongs to the national organization , is member of ATMO France Federation and approved by the French ministry for ecology.
Among its missions : providing measurement, expertise, advice and information.