Understanding Nitrogen Dioxide and its effects on Health

What is Nitrogen dioxide (NO2)?

Nitrogen dioxide (NO2) is a gaseous compound typically produced from combustion processes. It appears as a reddish-brown gas with a pungent odor at high temperatures. It is listed as one of the six critical pollutants that adversely affect indoor air quality under the National Ambient Air Quality Standards (NAAQS).

Some common indoor sources of nitrogen dioxide include:

  • Burning fossil fuels such as coal, gas, or oil
  • Fuel-burning stoves and heating systems
  • Tobacco smoke
  • Unvented appliances
  • Diesel-powered equipment

NO2 levels inside homes can also be affected by automobile emissions, especially if they are situated near busy roads.

Why do we need to monitor it?

A study in the Journal of Environmental Research shows that the immediate effect of inhaling high concentrations of nitrogen dioxide is irritation of the airways, whereas long-term exposure can cause chronic respiratory problems.

The American Lung Association (ALA) lists these harmful effects of exposure to nitrogen dioxide indoors:

  • Aggravation of asthma and other respiratory ailments
  • Wheezing, coughing, difficulty in breathing
  • Reduced lung function
  • Possible onset of cardiovascular diseases, lower birth weight of infants, and increased risk of premature death

Since it poses serious health risks, it is extremely important to ensure that it is not present in your indoor environment. It is important to know when the levels rise above a healthy threshold so that you can identify where the pollutants are coming from.

What are safe levels of Nitrogen Dioxide?

uHoo follows NO2 standards set by the World Health Organization (WHO) and US Environmental Protection Agency (EPA):

Good (0-100 ppb) Generally, no symptoms will be found in people when exposed to these levels.
Moderate (100-250 ppb) Nitrogen Dioxide levels in this range have been shown to cause respiratory discomfort in people who have issues, such as those with asthma
Unhealthy (250-500 ppb) This level of NO2 concentration will cause discomfort and potential health problems for any person regardless of health and age.

What are the benefits of managing Nitrogen Dioxide at home?

Protection from potential safety hazards

The higher NO2 levels are caused primarily by unvented combustion appliances indoors. Among these may be kerosene heaters, gas stoves or even smoke from tobacco. It is important to regulate this pollutant to prevent severe safety hazards, including fatalities. Controlling nitrogen dioxide thus saves lives literally.

Apart from health issues, high NO2 levels inside a building can also increase the risk of fire and explosion. Nitrogen dioxide can combust violently with a wide variety of substances, including hydrocarbons. A gas stove that is not properly vented or a heater that is improperly installed, for example, can result in serious fire or even explosion hazards. NO2 levels can and should be monitored in real time to prevent these potentially fatal accidents.

A safe and healthy indoor environment

In high-risk individuals with asthma and other respiratory conditions, infants and children, and the elderly, exposure to unhealthy NO2 levels can cause respiratory issues that often result in hospitalizations. Some people are more sensitive to this pollutant than others, so regulating it can ensure a safe, healthy, and productive working environment for everyone.

Controlling the concentration of NO2 inside also reduces the risk of viruses surviving and spreading through the air.

What can be done to manage Nitrogen Dioxide?

Make sure gas appliances are properly adjusted and maintained

If you must use gas-powered appliances such as stoves and heaters, check to ensure they are installed properly and are operating in accordance with the manufacturer’s instructions. You should maintain regular maintenance and cleaning to avoid gas leaks or untoward accidents caused by defective parts.

Use of exhaust fans

Especially at the sources of nitrogen dioxide, install exhaust fans vented to the outside. In order to avoid the spread of toxic fumes indoors, this must be done before they become airborne.

Use indoor air cleaners

High-efficiency air filters can help to reduce nitrogen dioxide concentrations indoors. Consider using air purifiers with HEPA and carbon filters to effectively remove pollutants like nitrogen dioxide from the air.

How does uHoo help in regulating nitrogen dioxide?

In addition to providing accurate nitrogen dioxide readings in real-time, uHoo can integrate with systems responsible for regulating NO2, such as your exhaust fans and air cleaners. The nitrogen dioxide levels are measured and monitored, and the data is relayed to you in an easy-to-understand color-coded system on the uHoo app. You get prompt alerts when NO2 levels are unhealthy along with some helpful tips so you can address the issue and improve your indoor air quality.


Becker, Susanne, & Soukup, J. (1999, August). Effect of Nitrogen Dioxide on Respiratory Viral Infection in Airway Epithelial Cells. Environmental Research. https://www.sciencedirect.com/science/article/ab s/pii/S0013935199939634.

Jarvis, Adamkiewicz, Heroux, Rapp & Kelly. (2021). Nitrogen dioxide.

NCEH. (2021). Chapter 5: Indoor Air Pollutants and Toxic Materials. Healthy Housing Reference Manual.

World Health Organization. (2005). WHO Guidelines for Indoor Air Quality: Global Update 2005

US EPA. (2021). Criteria Air Pollutants.

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