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| Pollutant | Maximum permissible concentrations, mg/m3 | Danger class | |
| 20 min | 24 hours | ||
| Nitrogen dioxide, NO2 | 0,085 | 0,04 | |
| Carbon monoxide, СО | 5,0 | 3,0 | |
| Sulphur dioxide, SO2 | 0,5 | 0,05 | |
| Soot | 0,15 | 0,05 |
The maximum permissible concentration MPC (maximum allowable concentration, (MAC), threshold limit value (TLV)) of a chemical substance is a level (volume or mass concentration) that the daily exposure for unlimited time on human does not cause any adverse health effects and does not lead to disruption of reproduction of natural ecological systems. Strictly speaking, TLV is a reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH).
Short-time maximum permissible concentration is also used in normative base for definition of emissions limits for different sources of air pollution, to estimate the size of sanitary-hygienic zone around the enterprise and to regulate strategic, technical and operational activities aimed to reduce adverse effects of air pollution.
Assessment of air quality in working area is based on:
(3.17)
Simultaneously content of air pollutants in the working zone of unidirectional impact sum relations of actual harmful substances concentrations (C1, C2, C3.... Cn) in working zone air to their CMPC (CMPC1, CMPC2, CMPC3 …. CMPCn) should not exceed 1.
Calculation is performed according to the formula:
(3.18)
Environmental legislation Ukraine includes the following normative base for air quality regulation and control:
· art. 5, 6, 9 Law of Ukraine "On Air Protection";
· State sanitary regulations of atmospheric air protection in residential areas № 201 of 09.07.97”
· State sanitary regulations of residential areas planning № 173
· State Standard Specification № 12.0.003-74 „Dangerous and adverse industrial factors. Classification”.
Air contamination level by harmful substances may be controlled by gas analyzers. Working process of the known gas analyzers is based on the following methods: spectrometry, chromatography, potentiometry, and spectroscope. One of the perspective methods of quantitative determination of harmful substances in air is the method of gas chromatography. Gas chromatography, applied in practice of hygienic research, opens wide possibilities for separation of mixtures into particular components, allows to identify the type of substance, to define their quantitative composition. Making use of capillary and high effective printed columns, it is possible to achieve such a component separation, which is impossible to obtain by other methods.
Example: Indicate whether the air quality level in habitation area in the vicinity of a thermal power station (according to calculation results of previous example) corresponds to the standards of the current legislation of Ukraine.
The maximum short-term concentration СMU of sulphur dioxide (SO2) is obtained 0.18 mg/m3 from emission of boiler plant of thermal power station for specified wind direction (U=3 m/s).
Short-term maximum permissible concentration of SO2 is 0.5 mg/m3.
So, СMU < CMPC by 2.7 times. Thus, air quality corresponds to the established standards.
Conclusion: Air pollution by sulphur dioxide in habitation area in the vicinity of thermal power station corresponds to standards of the current legislation of Ukraine.
Problem 3.4: Assess the maximum permissible emission and size of sanitary-hygienic zone for considered industrial dangerous object taking into account the perspective of enterprise development and the average annual wind rose of the area of industrial object location
In accordance with mentioned before requirements of the standard rules and normative documents, maximum permissible emission (MPE) and size of sanitary protection zone for industrial enterprise has been determined to provide human safety in residential areas.
Maximum permissible emission (MPE) of harmful substances into the atmosphere is established for each stationary source of air pollution in such a way, that surface concentration of harmful substance from the emission source does not exceed MPC for habitants, flora and fauna. MPE takes into account perspective of development of industrial enterprises and mechanisms of pollutants dispersion in the atmosphere (GOST 17.2.3.0278).
Establishment of MPE is implemented by application of the methods of calculation of air pollution from production facility taking into account the perspective of enterprise development, geographic and climatic conditions of considered area, the location of industrial sites and the sites of residential development, recreational areas of cities.
MPE (g/s) is set for technological conditions (full load) by gas cleaning consideration. MPE is defined for each substance separately, including harmful effect summation of several substances.
The value of MPE of harmful substance from a stationary source with a round orifice is calculated by the formula:
(3.19)
where A is the coefficient that depends on the temperature stratification of the atmosphere and climatic conditions of the region (A = 160 for Ukraine); M is the emission rate of air pollutant, g/s; F is the dimensionless coefficient that depends on the rate of air pollutants sedimentation in the atmospheric air. Thus, F = 1 for gases; F = 2 ÷ 2.5 for fine particles matter and coefficient purification of emissions 75-90%; F = 3 for coefficient purification of emissions less than 75%; m, n are coefficients, that take into account the emission conditions of air-gas mixture from stationary source with a round orifice and are calculated by the formulas (6, 7); H is the height of stationary source of emission over the ground surface, m; η is the coefficient, which takes into account the terrain impact on concentration values of air pollutants, η =1; Δ T is the temperature difference between exhaust gases Te and ambient air Тa; V 1 is the exhaust air-gases rate, m3/s; MPC is the short term maximum permissible concentration of harmful substance; Cb is the background concentration of harmful substance, mg/m3.
In cases where the maximum allowable emission for objective reasons cannot be achieved at the present time, it provides for a phased reduction of emissions and determines the temporarily agreed emission in accordance with current technical capabilities.
One of the important approaches to reduce emissions is to define the boundaries of the sanitary protection zone around the enterprise.
Sanitary Protection Zone (SPZ) is a special area with a special, which is set around production facility and enterprise, which causes adverse impacts on the environment and human health. In other words, SPZ is the distance (radius) from the production facility to the point where the concentration of pollutants does not exceed the MPC.
Thus, determination of the boundaries of SPZ around the production facility is aimed at reducing air pollution levels to the values of established hygienic standards.
The size of SPZ is established according to the sanitary classification of enterprises, manufacturing and industrial objects (ДСП№ 201 [3.1]). This classification takes into account the emission efficiency, the nature, properties and amount of harmful substances released into the environment (Table 3.2).
Table 3.2
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