One of the main gases causing air pollution is nitrogen dioxide (NO2). Nitrogen dioxide is also extremely dangerous for human health. The most important source in the formation of nitrogen oxides in crowded settlements is motor vehicles. Serious efforts should be made to reduce their emissions of nitrogen dioxide. In addition to air pollution, another harmful effect of nitrogen oxides is the formation of ozone, especially in summer days.

At high temperatures above 1000, the nitrogen molecules in the air react with oxygen during the combustion process and chain reactions begin as oxidized. In this case, nitrogen monoxide (NO) is formed. The higher the temperature, the faster the rate of such reactions. During the combustion process, a small amount of nitrogen dioxide is formed with nitrogen monoxide. Nitrogen monoxide, mixed with air from car exhausts and chimneys, is rapidly oxidized by ozone gas and converted to nitrogen dioxide.

In short, there are two important sources of nitrogen dioxide:

• Thermal power plants burning above 1000 using solid, liquid or gas fuel
• Motorized vehicles

Nitrogen oxide gases generally have acidic properties. With the help of the winds, it can be carried far away in the atmosphere. Nitrogen dioxide is brown in color.

Nitrogen dioxide can sometimes be higher in the building than the outside value. Gases emitted from the heaters used indoors may accumulate inside the building. In addition, the concentration of nitrogen dioxide is generally very high in areas where traffic is very heavy. Nitrogen dioxide formation is accelerated and emissions increase, especially when low-quality fuels are used in motor vehicles or when motor vehicles are used at very high speeds. Nitrogen dioxide emissions are also high in thermal power plants and industrial plants using fossil fuels.

Nitrogen dioxide is a gas heavier than air and readily dissolves in water to form nitrate and nitrite acid. This causes acid rain.

In order to control the release of nitrogen dioxide into the air, the following facilities must be continuously monitored, measured and analyzed:

• Thermal power stations
• Cement Industry Plants
• Fertilizer manufacturing equipment
• Glass manufacturing equipment
• Garbage incineration plants
• Ceramic production facilities
• Briquette production facilities
• Hot asphalt production plants
• Paper Production Plants

In addition, the motor vehicles that come into traffic must also be strictly inspected.

Occupational health and safety regulations require the determination of exposure of workers to a number of chemical substances in the workplace. For this purpose, some measurement, test and analysis studies are required by employers. Nitrogen dioxide measurements in the environment should be made according to the field of activity of the enterprises. These measurements are carried out by authorized test and inspection institutions. During the measurements, legal regulations in force and standards published by domestic and foreign organizations are taken into consideration.

The limit values ​​for nitrogen dioxide in various countries are as follows:

• In our country: 24 temasg / m300 for 3 hour contact time, 100 µg / m3 in one month
• According to the World Health Organization: 1 µg / m200 for 3 hour contact time, 40 µg / m3 in one year
• In European Union Countries: 1 µg / m200 for 3 hour contact time, 40 µg / m3 in one year
• In the US: 1000 µg / m3 in one year