What is air pollution?
The air is composed of a mixture of gases (78% nitrogen, 21% oxygen, 0.09% argon, 0.03% carbon dioxide, 0.07% water vapor and other elements in traces). The presence of substances that are not part of normal air is called air pollution. The impact of air pollutants on the health of the population depends on their concentration, exposure time and individual sensitivity of individuals and / or certain population groups.
Aerial pollutants are usually invisible, although in certain situations, concentrations of pollutants are so high that the atmosphere can see a yellow-brown or grayish-white mist in the air. Its main components are: sulfur dioxide, nitrogen oxides, ground level ozone / and particulate matter, or the so-called PM-particles.
Sulfur dioxide (SO2) is a colorless reactive gas that has a specific sharp odor at higher concentrations. It is released when combustion of fossil fuels. Hence, the main sources are communal and local fireplaces, thermal power plants and exhaust gases of vehicles.
Nitrogen oxides (NOX) is a common name that denotes more diverse associations of nitrogen and oxygen, which are usually generated in the process of high temperature combustion. Main sources of nitrogen oxides are thermal power plants and motor vehicles. Nitric oxide (NO) is the dominant gas generated by combustion, and transformed into nitrogen dioxide (NO2).
Nitrous oxide is a light brown gas that has a characteristic pungent odor at high concentrations. Nitrogen dioxide is important in the creation of photochemical air pollution.
Carbon monoxide (CO) is a colorless gas, odorless and flavor generated by incomplete combustion of carbon-containing fuels. The main sources are industry, shelters and vehicles.
Ground-level ozone (O3) is not a pollutant directly emitting in the air. It is a colorless gas produced in a photochemical reaction under the influence of sunlight from other air pollutants (mostly nitrogen oxides and volatile organic hydrocarbon compounds – VOCs). Therefore, it belongs to the group of so-called secondary pollutants. And while ozone in high airborne layers protects the earth and its living world from harmful ultraviolet radiation, groundwater ozone is harmful to human, animal and plant health. Of course, concentrations of ground-level ozone are higher in summer, sunny days.
Suspended PM particles (PM) are very small, fine, solid or liquid particles suspended in the air. According to their origin, they can be from dust, soot, smoke, from chemical pollutants generated by factories, vehicles, domestic and utility boxes, construction activities or simply can be from natural dust or dirt in the communal environment. According to their size, they are divided into two large groups – PM10 with a particle size of 10 microns, still called respirable suspended particles and PM2.5 with a particle size of 2.5 microns. They are called fine suspended particles. Their chemical composition depends on the characteristics of the local air pollutants and can contain heavy metals, nitrates, sulphates, ammonia, hydrocarbons, silicon dioxide, etc.
Air pollution depends on the intensity of the source of pollution, the meteorological factors and the topography of the space. Meteorological phenomena such as wind, moisture, or temperature inversion can affect the spreading, but also the retention of air pollutants in the air, thereby causing deterioration in air quality.
Bearing in mind this, certain countries, including the Republic of Macedonia, have developed an air quality index – AQI. The air quality index is a new measure introduced in the air quality display system called “Moj vozduh” (https://mojvozduh.eu/web/). This index makes the sum of all measured values of individual air pollutants on a scale of 1-100. Measure below 25 means very low pollution, below 50 – low, under 75 – medium, under 100 – high, and above 100 – extremely high.