3.1. Sources and composition of atmospheric contaminations. Hazard rating of atmospheric contaminants. Emission composition classification
Sources of atmospheric contamination can be of two types: natural or man-induced. Natural sources include space dust; rock and soil destruction and weathering; waste products of plants, animals, soil bacteria, volcano eruptions.
Man-induced sources include thermal engineering, industries, vehicles, nuclear power plants, atomic tests.
Most common industrial emissions are soot, dust, NOx, SO2, SO3, CO, CO2, ozone, hydrogen chloride, hydrogen fluorine, ammonia, ZnO, PbCl2, silicates, volatile hydrocarbons and their products, hydrogen sulphide, phosphorus compounds, and chlorine.
Emissions from chemical and pharmaceutical enterprises contain drug dust, e.g. streptocide, norsulfazole, paracetamol, acetylsalicylic acid, etc.; CO, NOx, SO2, hydrocarbons, aerosols of antibiotics — penicillin, streptomycin, carbolic acid, etc.
A major source of atmospheric pollutants is vehicle exhausts. Main components of exhausts are carbon oxide and dioxide, nitrogen oxide, sulphur dioxide, cancerogenic hydrocarbons, including benzapyrene, dioxins, tetraethyllead.
Sources of pollution can be stationary (industrial enterprises) or and mobile (transport).
Industrial emissions can be controlled and uncontrolled.
Controlled industrial emissions are emissions to the atmosphere via special gas pipes, air ducts, opens, fans.
Uncontrolled industrial emissions enter the atmosphere in the form of uncontrolled gas flows as a result of compromised equipment air-tightness, in areas of loading and unloading of products, raw materials, as well as in raw materials storages.
Atmospheric pollutants are divided into 4 hazard categories:
- extremely hazardous;
- highly hazardous;
- moderately hazardous;
- negligibly hazardous.
Emission composition classification (not applicable to radioactive and biological substances).
Atmospheric emissions are characterized on the basis of four parameters:
- aggregate state: A — gaseous, K — liquid, T — solid;
- chemical composition: 01 — SO2, 02 — CO, 03 — NOx, 04 — F2 and its compounds, 05 — CS2, 06 — H2S, 07 — Cl2, 08 — HCN and cyanides, 09 — Hg and its compounds, 10 — NH3, 11 — As its compounds;
- particle size (m): 1 — less than 0.5×10–6, 2 — 0.5×10–6 to 3×10–6, 3 — 3×10–6 to 10×10–6, 4 — 10×10–6 to 50×10–6, 5 — over 50×10–6;
- substance weight (kg/h): 1 — less than 1, 2 — 1 to 10, 3 — 10 to 100, 4 — 100 to 1000, 5 — 1000 to 10,000, 6 — over 10,000.
If an index is absent, «0» is used.