Sulfur dioxide falls into the group of sulfur oxides (SOx), which are formed in the course of high sulfur content fuel burning. The basic anthropogenous source of sulfur dioxide is natural fuel burning (TEPS, household sources). Metallurgy and chemical industry are also sulfur dioxide pollution sources. SO2 and NOx are the main components of the “acidic precipitiation”.

Impact on human health
Sulfur dioxide penetrates the human organism through the respiratory system. At high concentrations its absorption reaches up to 90% in the upper respiratory tract and less in the lower parts of the respiratory system.
During short-term exposure to sulfur dioxide mainly the respiratory system is affected.
Large diversity is witnessed with respect to the individual sensitivity of the population to sulfur dioxide, but individuals suffering from bronchial asthma are particularly sensitive. The effect of sulfur dioxide on the respiratory system as a rule is accompanied with the impact of dust.
Population groups sensitive to sulfur dioxide exposure are children, elderly, asthmatic patients, people suffering from cardiovascular diseases or chronic lung diseases. Sulfur dioxide health effects are expressed in respiratory disorders, lung diseases, lung immune protection disorder, aggravation of existing lung and cardiovascular diseases. It is difficult to separate the effect of sulfur dioxide from that of dust, in terms of increased hospitalization and death rate. The asthmatic patients are 10 times more sensitive to sulfur dioxide than healthy people. Children, suffering from asthma are particularly sensitive, and sulfur dioxide exposure may lead to inflammatory lung diseases.

The sulfur dioxide limit values are set with Regulation No 9 (State Gazette No. 46/1999, amended and supplemented, SG No. 86/2005). The introduced LVs aim at prevention of the harmful effect of sulfur dioxide. The set sulfur dioxide LVs are as follows: - 1-hour LV (for 1 hour exposure) - 350 µg/m3;
- 24 hour average LV (for 24 hour exposure) - 125 µg/m3;
- alarm threshold - 500 µg/m3, measured during three consecutive hours by the monitoring stations, which are representative for the air quality in not less than 100 km2, or a certain whole region or agglomeration, irrespective of which of these three territories is the smallest.
If the alarm threshold is exceeded measures should be taken for limitation of the adverse effect of the pollutant.