Introduction: The growth of technology and industry has brought prosperity to mankind on the one hand, but on the other hand, it has caused the creation of physical, chemical, and biological pollutants in the environment and by creating unfavorable conditions in the work environment, it has endangered the basis of a healthy life. Suspended particles (Particulate Matter (PM)), sulfur oxides (SOx), nitrogen oxides (NOx), and carbon monoxide (CO) are among the standard and important pollutants in air pollution. In this research, the pollutants emitted from the chimneys of Semnan gypsum industries including carbon monoxide, sulfur dioxide, nitrogen oxides, particulate matter (PM₁₀), and dry dust have been studied in five Semnan gypsum factories.
Materials and Methods: The concentration of PM₁₀ and dry dusts was determined using a particle measuring device (TCR-Tecora) and a Testo 350-M/XL device was used to measure gaseous pollutants. Sampling of industrial chimneys as well as the space around the factories has been done in four places. Also, risk assessment has been done by the William-Fine technique, which is a systematic risk assessment method to identify possible risks, estimate the level of risk in risk management, and reduce it to an acceptable level.
Results: In this study, the amount of NOx is between 24.5 and 39 ppm, the concentration of SO₂ is between 33.44 and 321 ppm, the concentration of CO is between 5 and 100 ppm, the concentration of PM₁₀ pollutant is between 2.68 and µg/m³ 97.66, ​​and the concentration of dry dust between 53.23 and 31896 mg/m³ was reported in the five investigated industries. For environmental assessment, 40 environmental aspects were identified using the William-Fine technique. For pollutants CO, SO₂, NOx, PM₁₀ and dry particles according to the risk priority number (RPN) calculated and according to the results of the category length, 4 risk classes were obtained with titles of very high, high, medium and low risk. Based on the ranking of 40 environmental aspects, the frequency of low category was 22, average category was 4, high category was 4, and very high category was 10. In gypsum units No. 3 and 4, the risks of PM₁₀ suspended particles were among very high risks. Also, the risk related to dust dry in both chimney of factory No. 5 was reported at a very high level.
Discussion: The concentrations of carbon monoxide, sulfur dioxide, nitrogen oxides, and dry dusts are lower than the standard values ​​of the Environmental Protection Agency (EPA) related to chimney emissions (carbon monoxide: 435 ppm, sulfur dioxide: 800 ppm, nitrogen oxides: 350 ppm and Dry particles: 600 mg/m³). The concentration of PM₁₀ based on the standard of the World Health Organization (WHO) was higher than the permissible limit (50 µg/m³), while it was lower than the permissible limit based on the EPA (150 µg/m³). The entry of PM₁₀ suspended particles into the atmosphere and also the accumulation of dusts in the environment around the factory is one of the important environmental problems of gypsum factories. Based on the classification, 55% of the aspects were at the low risk level, 10% of the aspects were at the medium risk level, 10% of the aspects were at the high-risk level, and 25% were at the very high-risk level. Finally, in order to reduce the level of risk and for the effective management of these industries, measures such as changing the used fuel to clean fuel, regular monitoring of the quantity and quality of the exhaust gas flow from the industrial chimney, using filter masks when in contact with dust, replacing bag filters Impact type with jet pulse type is remarkable.