Name: Nitrogen Dioxide
Definition: Nitrogen dioxide is the chemical compound with the formula NO2 It is one of several nitrogen oxides. NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year which uses is primary in production of fertilizers. At higher temperatures it is a reddish-brown gas that has a characteristic sharp, biting odor and is a prominent air pollutant.
Chemical Composition: (NO2)
How it is Produced: Nitrogen dioxide is a nasty-smelling gas. Some nitrogen dioxide is formed naturally in the atmosphere by lightning and some is produced by plants, soil and water. However, only about 1% of the total amount of nitrogen dioxide found in our cities’ air is formed this way.Nitrogen dioxide is an important air pollutant because it contributes to the formation of photochemical smog, which can have significant impacts on human health. The main source of NO2 is by burning fossil fuels like coal, oil, and gas.
Effects: The main effect of breathing in raised levels of nitrogen dioxide is the increased likelihood of respiratory problems. Nitrogen dioxide inflames the lining of the lungs, and it can reduce immunity to lung infections. This can cause problems such as wheezing, coughing, colds, flu and bronchitis. Increased levels of nitrogen dioxide can have significant impacts on people with asthma because it can cause more frequent and more intense attacks. Children with asthma and older people with heart disease are most at risk.
Units: Air is drawn into the analyser where nitrogen monoxide (NO) is made to react with ozone, to give nitrogen dioxide in a reaction that generates light: Nitrogen monoxide + ozone » nitrogen dioxide + oxygen + light emission.
This method doesn’t actually measure nitrogen dioxide but calculates the airborne levels of nitrogen monoxide and total oxides of nitrogen (NOx), and then subtracts one reading from the other. The final results are expressed in parts per billion (ppb) or micrograms per cubic metre of air, this is written as µg m-3. Nitrogen dioxide is also measured using diffusion tubes.
Range: In micrograms per cubic meter:
- Good: 0 to 50 (Green)
- Moderate: 51 to 100 (Yellow)
- Unhealthy for Sensitive Groups (USG): 101 to 150 (Orange)
- Unhealthy: 151 to 200 (Red)
- Very Unhealthy: 201 to 300 (Purple)
- Hazardous: 301 and above (Maroon)