The particulate matter, nitrogen dioxide, and ozone on the surface are the pollutants that affect human health the most. Approximately 90% of European citizens are exposed to air pollutant concentrations higher than air quality levels considered harmful to human health.
How does air pollution affect the human body?
The air is the living environment of human beings, and obviously, a number of atmospheric parameters have great importance for the quality of life and human health. Atmospheric air quality is a key element of people’s comfort and well-being. According to the World Health Organization (WHO), air pollution severely affects the health of European citizens (between 2.5 and 11% of the total number of annual deaths are due to air pollution). Special attention is paid to primary emitted or secondary formed particulate matter, which size varies from 0.01 µm to 50 µm. They have the ability to adsorb on their surface a variety of chemical compounds, including some toxic substances such as heavy metals, NH3, NOx, VDCs, mutagens, and others. After 1990, the particulates are separate in several fractions: PM10 (Particulate matter, with diameter < 10μm), PM2.5 (Particulate matter with diameter < 2.5μm) and ultra-fine particulate matter with diameter < 0.1 μm (PM01). Particulate matters enter the body by the respiratory system, and depending on their size, are fractionalized in its different sections. Particles with a diameter of fewer than 2.5 μm reach the lung alveoli in a differentiated manner. Together with the compounds adsorbed on their surface, they can then get into the lung macrophages and throughout the body and generate harmful effects on human health. The connection between the increased frequency of respiratory, cardiovascular, and malignant diseases has been proven. A correlation was found between high average annual concentrations of PM10 and decreased lung function, as well as a positive relationship between the levels of some of the studied biomarkers of humoral and cellular immunity and atmospheric concentrations of PM2.5.
Fig.1 Limit values between the index for each pollutant
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AQI – Air Quality index
The AQI index is defined as a measure of air pollution considered in the context of its impact on human health. It provides an integrated assessment of the impact of the whole range of pollutants on human health and is calculated based on the concentration of various pollutants obtained from measurements or numerical modelling. The index is defined in several segments, each of which is a linear function of the concentration of each the pollutant considered. One of the most commonly used air quality indexes is the UK daily air quality index (de Leeuw and Mol, 2005). In Bulgaria the index, calculated in the frame of Bulgarian chemical weather forecast system. This index has ten points, which are further grouped into four bands: low, moderate, high and very high. The index is based on the concentrations of five pollutants. The index is calculated from the concentrations of ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2), PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM10.