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Everything to know about nitrogen dioxide (NO2)

Nitrogen dioxide (NO2) is a chemical compound part of a group of highly reactive gases known as oxides of nitrogen or nitrogen oxides (NOx). It is a common air pollutant recognized by many standard air quality guidelines, including the World Health Organization. At Breeze Technologies, NO2 is one of the more important air pollutants among the many monitored by our air quality sensors, and it is thus also included in our air quality index (AQI). Read on to find out why.

What is nitrogen dioxide?

Nitrogen dioxide (NO2) is an important atmospheric trace gas that is soluble in water. It has a reddish-brown color and is a strong oxidant. NO2 is formed through the oxidation of nitric oxide (NO) in combustion processes such as diesel engines and coal, oil, gas, wood, and waste plants. 

NO2 has many roles in the atmosphere and also in health effects. A few important roles of NO2 include:

  1. NO2 could have a potential direct role in global climate change if its concentrations were to be high enough, as it is an absorber of visible radiation, thus creating impaired atmospheric visibility and heating up the atmosphere. 
  2. NO2 plays a critical role in determining ozone (O3) concentrations in the troposphere (i.e. at ground level).  Through light absorption, NO2 is broken down through light absorption into O3 during a process called photolysis. This formation of O3 can occur in polluted and unpolluted atmospheres. 
  3. NO2 controls the build-up and fate of so-called “radical species,” as NO2 itself is a free radical (also written as •NO2). Free radicals are unstable atoms that have an unpaired electron and are dangerous when consumed in excess levels. Interaction between free radicals and oxidants can generate a phenomenon known as oxidative stress. Oxidative stress can damage the cells in our body and destroy other structures such as proteins, lipids, and deoxyribonucleic acid (DNA), thereby causing aging, illness and cell damage.

What are sources of nitrogen dioxide?

Emission of nitrogen dioxide (NO2) from natural sources comes from:

  • Lightning
  • Bacterial and volcanic action

NO2 emissions from human activities include the following:

  • Heating and power generation
  • Motor vehicles
  • Explosives and welding

NO2 indoor emissions from human activities comes from:

  • Tobacco smoking
  • Use of gas-fired appliances
  • Oil stoves

What is the health impact of nitrogen dioxide?

Exposure to nitrogen dioxide (NO2) is linked to adverse effects on the respiratory system. 

Short-term effects of NO2 can contribute to the risk of cardiovascular and respiratory death. Long-term effects of NO2 may lead to the development of asthma, increase the risk of respiratory infections and chronic lung disease. These respiratory symptoms include:

  • Coughing
  • Wheezing
  • Difficulty in breathing
  • Reduce ability to smell

Both pedestrians and drivers who spend time on major roads or traffic lanes can experience NO2 exposure considerably higher than less busy streets. NO2 also affects sensitive groups such as people with lung disease, children, and older adults. 

What is the environmental impact of nitrogen dioxide?

Nitrogen dioxide can fade and discolor furnishings and fabrics, reduce visibility, and react with surfaces. High levels of NO2 are also harmful to vegetation—damaging foliage, decreasing growth or reducing crop yields. 

Along with sulfur dioxide, NO2 can cause acid rain that can be corrosive to building materials at high concentrations. NO2 also forms secondary particles called nitrates that cause haze and reduce visibility. NO2 is the reason why summer smog can look brownish in color.

What are ways to decrease nitrogen dioxide?

Unlike ozone and particulate matter pollution, NO2 levels appear higher in close proximity to pollution (e.g. vehicles on major freeways or factories). In heavy traffic there are higher NO2 levels compared to residential areas or roads that are less traveled. In order to reduce NO2 levels in these crowded areas, here are some ways in which you can reduce your personal NO2 emissions:

  • Carpool or use public transportation
  • When air quality is healthy, bike or walk instead of driving
  • Combine errands to reduce vehicle trips
  • Conserve energy at home and at work

Breeze Technologies also provides an opportunity to learn and educate about air quality through the Clean Air Academy. Here all the relevant resources and information are provided in different sections starting from basic air quality knowledge to more specific knowledge about various air pollutants our Breeze air quality sensor can detect. In addition, you can also volunteer as an air quality host! Being an air quality host helps you be informed about the level of pollutants in the air you breathe. Join now to take better clean air actions to live a healthier life!