Coal dust exposure reduction using water mist system: A case study

Quantification of airborne dust exposure is an essential step in eliminating lung diseases caused by overexposure to dust. A large number of workers employed in coal boilers are potentially exposed to significant amount of airborne coal dust during the work period. The objective of the study was to assess the efficiency of water mist system in reducing airborne coal dust concentration in the working atmosphere near a coal fired boiler. Samples from eight workers were taken, representing approximately 80% of the total workforce involved in the coal handling operations. Exposure monitoring was conducted for 480 min during regular working hours. A personal dust sampler was used to capture the airborne coal dust (PM5) before and after installation of water mist system. After quantification and comparison, it was observed that the water mist system successfully reduced up to 81% of airborne dust from the worker's breathing zone. Further, the airborne dust concentration was reduced from 7.17 to 1.26 mg/m3 which is significantly below ACGIH recommended Threshold limit value (TLV) of 2 mg/m3. The same technology may be used in comparable work environments to reduce high airborne dust levels.