---
title: Nitrogen Oxide (NOx)
description: Nitrogen Oxide (NOx) can severely affect the air we breathe. These gases irritate airways and aggravate existing breathing problems, especially asthma.
---

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# [Nitrogen Oxide (NOx)](https://learn.kaiterra.com/en/air-academy/oxides-of-nitrogen-nox)

 Written by [Christine Johnson](https://learn.kaiterra.com/en/air-academy/author/christine-johnson) | Oct 22, 2018 10:38 PM

## **What Are Nitrogen Oxides** (**NO**x**)? **

NOx is an abbreviation for nitrogen oxides. They are a family of seven poisonous, highly reactive gases composed of nitrogen and oxygen. The two most hazardous NOx gasses are nitric oxide (NO) and nitrogen dioxide (NO2). Most of the NOx gases are colorless and odorless. However, NO2 can often be seen as a reddish-brown smog in many cities and heavily polluted areas.

Emissions of NOx cause an array of chronic health problems for people. As a result, they are heavily regulated in many parts of the world.

## **How Is NO**x** Created?** 

Nitrogen oxides form when fuels are burned at high temperatures. It’s a combustion reaction of nitrogen and oxygen. Areas with a high volume of motor vehicle traffic often suffer from significant NOx pollution. This pollution is created by man-made events such as:

- fuel combustion
- water waste treatment
- agricultural activities

## **What Is Nitrogen Dioxide (NO**2**)? **

Nitrogen Dioxide (NO2) is a type of nitrogen oxide. It has a characteristically pungent smell and reddish-brown color. NO2 plays a major role in atmospheric reactions that produce ground-level [ozone](https://learn.kaiterra.com/en/air-academy/ozone-o3), a major component of [smog](https://learn.kaiterra.com/en/air-academy/smog). The primary creator of outdoor NO2 is heavy traffic in urban areas. Indoors, NO2 is produced by unvented heaters, gas stoves, and cigarette smoke.

## **Nitrogen Dioxide and Air Pollution **

NO2 is a primary pollutant that helps in the formation of secondary pollutants like ozone (when in the presence of ultraviolet light) and [particulate matter](https://learn.kaiterra.com/en/air-academy/particulate-matter-pm).

High concentrations of NO2 and other forms of nitrogen oxides severely affect the quality of the air we breathe. These gases irritate airways and aggravate existing breathing problems, particularly [asthma](https://learn.kaiterra.com/en/air-academy/asthma). Long-term exposure contributes to [respiratory problems](https://learn.kaiterra.com/en/air-academy/respiratory-illness) and puts you at a higher risk of developing respiratory infections. Children and the elderly are at greater risk for the health effects of NO2.

In an effort to protect people from NO2 related health implications, the World Health Organization has created [a set of guidelines](http://apps.who.int/iris/bitstream/handle/10665/69477/WHO_SDE_PHE_OEH_06.02_eng.pdf?sequence=1) to protect the public from chronic nitrogen dioxide exposures and [air pollution](https://learn.kaiterra.com/en/air-academy/air-pollution).

### **Related links**

- [Ambient (outdoor) air quality and health](http://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health)
- [Nitrogen Oxides (NOx) Control Regulations](https://www3.epa.gov/region1/airquality/nox.html)

Kaiterra provides [air quality monitors](https://www.kaiterra.com/) and an IAQ analytics dashboard for [healthy buildings](https://www.kaiterra.com/indoor-air-quality-monitor-for-buildings) and [offices](https://www.kaiterra.com/indoor-air-quality-monitoring-office), helping workplace leaders and healthy building pioneers assess and improve their indoor air quality. Our indoor air quality monitors like the [Sensedge](https://www.kaiterra.com/sensedge) and the [Sensedge Mini ](https://www.kaiterra.com/sensedge-mini)can be found in many of the world’s most iconic buildings and workplaces, such as the Empire State Building and the Burj Khalifa.

[View full post](https://learn.kaiterra.com/en/air-academy/oxides-of-nitrogen-nox)

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