Nitrogen dioxide? Meet NO2

Learn more about NO2, nitrogen dioxide, and the effects on our health

Emissions

Air pollution is a matter of concern as it affects the world's population on a large scale. One of these pollutants is nitrogen dioxide, NO2, a very common, toxic gas known for its strong smell and brown color in some situations. Nitrogen gas (N2) and molecular oxygen (O2) react to form nitrogen monoxide (NO), which comes from burning fuel in car engines or in industrial furnaces where the temperature is very high. The NO oxidized in the atmosphere by O2 forms nitrogen dioxide (NO2) and can also react to form ozone.

Sources

Automotive vehicles, internal combustion engines, thermoelectric and steel mills and pulp mills are the main artificial synthesizers of nitrogen oxides.

Natural sources include forest fires, heat generated by lightning, and microbial activity in soils.

health effects

NO2 gives humans a pleasant sensation when inhaled. This is because it has anesthetic properties, but it is toxic to people and animals and long-term exposure causes serious damage to health.

The compound increases the sensitivity to asthma and bronchitis, especially in children, the elderly and risk groups (people with respiratory problems), in addition to being an irritant to the lungs and decreasing resistance to respiratory infections. A recent study by researchers at University of California, in the US, suggests a link between NO2 levels and the incidence of sudden death syndrome in newborns, there are also studies linking nitrogen dioxide to the incidence of autism (learn more here).

People who have diseases that may be aggravated by exposure to nitrogen dioxide should not be authorized to work with this product, as, in high concentrations, it can cause delayed chemical pneumonia, pulmonary edema, irritation of the nose mucosa (manifested through coryza), severe damage to the lungs, similar to that caused by pulmonary emphysema, and continuous exposure can cause permanent impairment of lung function.

Effects on the environment

When oxidized in the atmosphere, nitrogen oxide produces nitric acid (HNO3), one of the components that increases the acidity of rain, and causes many damages to nature because it is corrosive. Acid rain, when falling to the surface, alters the chemical composition of soil and water, affects food chains, destroys forests and crops, corrodes metallic structures, historical monuments and buildings.

Often, the fact that the sky is brown in cities with so many vehicles, such as São Paulo, is due to the formation of NO2 in the atmosphere, added to the large emission of particulate matter that also darkens the atmosphere. It also plays an important role in the formation of photochemical oxidants such as ozone, responsible for smog photochemical.

NO2 measurements indicate the location of its source, as the residence time of this pollutant is approximately one day, thus being concentrated very close to the polluting sources. Looking at the map below, we see high levels of pollutant concentration in large cities and lower levels in poorly urbanized areas

World map

Alternatives

At home, we can produce NO2 when cooking (learn more substances that we produce when cooking), so it's important to have air-purifying plants and take some day-to-day care to improve the air quality in our home. Check a list of hits and misses at home.

One of the techniques that greatly reduced the concentration of NO2 is the catalytic converter that most modern cars have. The catalytic converter (or catalyst) contains metals such as palladium, platinum and rhodium, which transform most of the gases harmful to health and the environment into inert gases.

The use of cleaner diesel in heavy vehicles and aviation biofuels also help to reduce the emission of nitrogen oxides.



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