What is nitrogen dioxide ?

Posted on , by Gregoire
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photo dioxyde d'azote

I already wrote about air pollution, let’s focus now on nitrogen dioxide (NO2) which is very probably the most harmful of all gas. I think that a thorough understanding of air pollution should facilitate a quicker change in mindset. What is that gaz which harms our environnement and bodies so severely.

Definition of nitrogen dioxide ?

Nitrogen dioxide  is a member of the nitrogen oxide family. The two of its constituents, nitrogen dioxide and monoxide, are the main air pollutants on earth.

It serves as a precursor for a variety of dangerous secondary pollutants, including ozone and small particles.

Because we can see and smell it, NO2 gas is simple to identify. In fact, it can be identified by its reddish-brown color and distinctively strong odor. It is a stench that is generally present on streets that have been heavily jammed.

Nitrogen dioxide can be seen easyly

Where does NO2 comes from ?

Concretely speaking, the transformation of the nitrogen present in the air, which makes up 80% of the air we breathe, is what causes NO2 to occur in chemistry. This nitrogen will oxidize at high temperatures and become NO2 gas when it comes into touch with oxygen.

Internal combustion in car engines—mostly diesel ones—and thermal power plants are the principal sources of this gas. Therefore, the primary offenders are industry and cars.

This was clearly evidenced during Covid Lockdowns when telework refrain workers from using their cars to commute.

Air quality during covid 19 in Los Angeles

How do we monitor Nitrogen dioxide ?

We rely on the AQI, the Air Quality Index, to determine whether our atmosphere is polluted. The AQI is calculated by taking into account measurements of the six main pollutants, including PM10 and PM2.5 particules and in particular NO2 is the most commonly occurring air pollutants in this index.

There are many apps that help to monitor pollution effects in most of large cities.

Air quality website to monitor nitrogen dioxide

Where is NO2 pollution most prevalent in our area ?

We now understand that automobiles are the primary offenders and that road traffic contains the highest quantities. Therefore, those who live close to busy roadways are most impacted by pollution. If a person has gas-fired home appliances, they may also be exposed to pollution there. This includes devices like gas and oil burners, as well as water heaters. If you smoke, you might also encounter it at home because cigarette smoke also contains NO2.

You won’t have a question that this gas is poisonous. What is more unexpected is that this gas is hazardous to both individuals and the environment.

Environnemental effects of nitrogen dioxide ?

The poisonous rust-colored gas Nitric acid is created from nitrogen dioxide once it is in the atmosphere and it then falls to the ground, especially on vegetation. This mechanism will aid in the development of acid rain as well as the acidity of lakes and soils. Nitric acid, which is produced when NO2 is converted, can also corrode metals and stain fabric, harming both.

In the end, nitrogen dioxide severely damages plants and crops leading to nutrient pollution but also  buildings.

Is nitrogen dioxide unhealthy for humans ?

NOx in general, including nitrogen dioxide, can harm our respiratory systems. In fact, this gas will reach the most minute respiratory repercussions because to its extremely small size. Its toxicity will make respiratory issues more likely in already vulnerable persons, such as youngsters and people with asthma. Children are especially vulnerable because they breathe more quickly than adults do, plus they are smaller, lower, and consequently closer to vehicle exhaust pipes.

High exposure cases can result in acute respiratory poisoning, which can manifest as coughing, dyspnea (difficulties breathing), and hemoptysis (release of blood when coughing). Finally, all lung malignancies that are unrelated to smoking are linked to ambient air pollution.

A sizable recent study discovered evidence that NO2, ozone, and other outdoor air pollutants increased the risk of lung cancer in humans. The 2016 study followed the air pollution levels that more than 350,000 cancer patients in California experienced from 1988 to 2011. The researchers discovered that their survival was decreased by exposure to these air contaminants.

Beyond the lungs, more recent studies have connected NO2 to cardiovascular damage, lower baby birth weights, and an increased risk of premature mortality.

What is advised by the World Health Organization (WHO) ?

The World Health Organization and European guidelines concur that the average yearly NO2 concentration shouldn’t be more than 40 g/m3. The hourly average concentration is similarly limited to 200 g/m3.

Beyond the WHO-recommended limits of g/m3, whether on an hourly or annual average, poses a risk to human health.

What is being done to reduce NO2 pollution?

Utilizing fuels with low nitrogen content is one method of reducing NOx emissions. Another is to alter the combustion process to produce less NOx. Nox can be eliminated using flue gas treatment methods including Selective Catalytic Reduction (SCR) technologies.

For sure developped countries nitrogen dioxide concentration levels reduce every year thanks to :

  • Public transports deployment
  • More sophisticated engines in modern cars
  • Speed limit reduction on both highways and downtown
  • Hydrogen technology development for trucks and buses
  • Hybrid and electric cars expansion
  • The incredible explosion of bike commuting in large cities

This is reflected in this chart showing drastic Nitrogen dioxide level drop in the UK from 1998 to 2020

Nitrogen dioxide decrease in the UK

Do pollution masks protect from nitrogen dioxide ?

More and more individuals are becoming concerned about the issue as air quality deteriorates, such as during pollution or pollen events, and are looking for protection.

They can then use a pollution mask.

Two crucial criteria must be considered:

  • Effectiveness: which contaminants and to what size will my mask filter out ?
  • Will the air from the outside get inside my mask, or is it hermetically enough sealed ?

Therefore, at Frogmask, I have created a solution that precisely satisfies both of these requirements:

We will filter 94% minimum of the outside air thanks to FFP2 filtering airborn particules up to 0,4µm.

Frogmask is one of the few brands proposing 3 different sizes (M,L and XL) as one size fits all is a real non sense. How one size mask can fit with all different sizes and face shapes ?

All coughing and irritation will cease immediately. Regarding the long-term results, your body will be grateful.

Girl on a scooter with a face mask