Occupational Hygiene Survey - Essay Example

Occupational Hygiene Survey Report Introduction The study produced a result of potential hygiene hazards posting to sawmill workers. The purposes of the study are to: To survey the occupational hygiene for a local sawmill. To identify type of hazards existing in a sawmill environment. To determine the level of dust hazards in the sawmill. To recommend ways to prevent hazards and reduce the impact of hazards. The study was conducted at the Lafarge Sawmill Ltd. Process Description In this particular sawmill, there are a few job groups each with is located at different area in the plant and with different responsibilities. Due to their difference in functions, their exposure to dust is different. Following is a table showing the job groups. Area Personnel Involved No. of Personnel Sawmill - front end Sawyers, rig operator, canter operator, Mark II operator, edgers, gateman, dropsort. 16 Sawmill - other Rover, utility, trimmerman, trim saw, bio attendant, stacker, stick placer, quality control, labourer 15 Planer - front end Tilt hoist, planer feeder, planerman 10 Planer - other Grader, bin attendant, stacker, bander, utility, cleanup, piler, quality control 22 Lumber yard Sawmill outfeed, kiln operator, planer infeed, blocker, forklift operator, trackmobile operator 12 Log yard Le Tourneau, log loader, yard equipment operator, bucker, bander, scalet. 12 Clean-up Clean-up, general utility, general labourer 9 Methods and Measurements Sampling method The study was conducted in between of 10th February to 9th March, 2007. Sampling was conducted on twice a week on Monday and Wednesday. The study was replicated for 6 times in within three weeks. Subjects (workers) of study were required to collect dust sample by using filters attached to pumps hung on the belts. The weight of dust sample was used to determine the exposure level of dust. Besides, the samples were chemically analyzed to determine the level of resin acids. In addition to that the details of the subject, environmental factor like temperature and relative humidity was recorded Air samples were collected too for analysis of microbiological content. Sampling was done several areas. Samples were collected simultaneously for a sampling period of 5 minutes. A sample was collected outside the gate of the factory to be a representative of ambient condition. Samples were then sent back to the laboratory for analysis. Inhaled dust sampling and analysis A seven-hole inhalable dust sampler (JS holdings, UK) was used to collect dust sample. The sampler was with 0.45m pore sizes, 25mm diameter Teflon Filters (Costar). This device was used to collect sample inhalable, as if inhalation through one's nose. The resemblance of the mechanism allowed study on health hazards by the dust inhaled. Teflon filter were used in order to collect particles for resin acids analysis. In the study, air was drawn through the sampler at the speed of 2 litre/minute. Four samples were taken for each location respectively. The weight of dust was determined by subtracting the pre-weight of the filter from the post-weight. All the weight measurement was conducted on the micto-balance (0.001mg sensitivity). Samples were equilibrated to the same temperature and relative humidity. All readings were taken at temperature 20+0.5 C and 50% relative humidity. Resin Acid Analysis There are two categories of resin acids: abietic and pimaric acid. The amount of acids exist in the dust depends on the species, maturity and storage condition. Method used to analyze resin acid was developed by Victor Leong and Mary Ellen Cassinelli (Pengelly, 1994). The quantity of abietic and pimaric acid was determine by a gas chromatography methodology. From the previous analysis, the Teflon filters were shifted into 100mm glass tubes with phenolic caps. 3ml of dichloromethane was used to extract the filters under ultrasonic bath for 30minutes. The extract was filtered with 24mm diameter 0.45 m pore nylon syringe filters. It was then washed with 0.5 ml of dichloromethane for two times before transferred to a clean glass tube. The dichloromethane was then allowed to be evaporated under a slow stream of nitrogen to dry. After evaporation of the solvent, the resin acids were derivatized to methyl ester by adding 100 l of dichloromethane and 50 l of N,N-dimethylformamide dimethyl acetal followed by 30 minutes heating at 60 C using a water bath. The samples were again evaporated to near dryness under a slow stream of nitrogen followed by addition of 1ml of methyl stearate internal standard (35mg of methyl stearate in 100ml dichloromethane). The solution was ready for gas chromatography. The gas chromatography unit used for this assay was Varian Model 3400 GC equipped with Septum programmable injector and a 30 Meter x 0.25 mm ID x 0.25m PTE-5 column. Helium was used as the carrier gas. The flowrate was 44cm/second measured at 150 C. The injector was set at 250C and the GC was set from between 150 to 250 C to 285 C and finally at 300 C for 2.6minutes. Saturn II Mars Spectrometer in EI mode was used to detect the chemical compounds. The area for peaks for methyl stearate, methyl pimarate (pimaric acid) and methyl abietiate (abietic acid) were quantified using area counts. Airborne Microbial Load Analysis The air samples were collected using a Merck MAS-100 air sampler. The amount of air drawn for sampling was 2 litres at a flowrate of 1 litre/minute. A standard 100ml agar plate filled with agar was placed inside the air sampler. Agars used were Malt Extract Agar (MEA) for fungal cultivation and Tripticase Soy Agar (TSA) for thermophilic bacterial cultivation. Air samples were drawn through a cover with 300 pores, and impact with the agar surface. Eight MEA and four TSA respectively were used at each location. After sampling, the agar plates were removed and covered. Four MEA plates were incubated at room temperature for 5 days for study of mesophilic fungal. Four other MEA plates were incubate at 37C for 48 hours for cultivation of thermophilic fungi. TSA plates were incubated at 55C for 48 hours for cultivation of potential pathogenic thermophilic bacteria. Colony forming units (CFU) for each plate were counted after incubation. Biochemical tests were carried out using API kit for bacteria identification. Results and discussion Inhaled Dust Level Table 1: Mean Inhalable Dust level (mg / m3) by area. Area / workers Mean Standard Deviation Sawmill - front end 0.65 0.45 Sawmill - other 1.59 1.41 Planer - front end 2.61 1.95 Planer - other 0.67 0.32 Lumber yard 1.84 1.52 Log yard 3.54 5.10 Clean-up 5.36 6.89 From table 1, it was obvious that the clean-up area had the highest dust level, which is 5.36 mg / m3. This is followed by the log yard, 3.54 mg / m3 and front end of planer, 2.61 mg / m3. The cleaning personnel who frequently used the compressed air to blow down recorded the highest level of dust inhaled. The level of inhaled dust was lower for those cleaners which used the compressed air less. The compressed air blown the dust to which causes a higher inhalation rate. Besides, it was noticed that the dust level was higher when the temperature of the environment gets is higher, especially on a hotter day. The increased in temperature increased the dryness of the dust. Thus, the density of the dust decreased and this make it lighter and could be blown into the air easier. Resin Acid Exposure Table 2: Mean Resin Acid level (g / m3) by area. Area / workers Abietic Acid Pimaric Acid Mean Standard Deviation Mean Standard Deviation Sawmill - front end 12.68 13.29 1.38 1.63 Sawmill - other 17.65 13.72 1.78 1.78 Planer - front end 63.05 55.36 3.55 3.77 Planer - other 10.23 13.62 0.63 0.80 Lumber yard 2.54 1.96 0.37 0.84 Log yard 4.76 5.57 0.44 0.56 Clean-up 99.50 90.69 7.19 7.27 As for the resin acids content, the results for seven different areas were recorded in table 2. The amount of abietic acid was about 8 times higher than pimaric acid from all areas. The highest resin acid occurred in the clean-up area followed by the front end of planer. Meantime, the lowest resin acid level was found in the lumber yard. The level of resin acid did not parallel with the inhalable dust level. Possible reasons could be due to different composition of wood dust. There were three types of woods being processed in this factory: spruce, fir and balsam. Different type of tree species would have different resin acid profile. Thus, perhaps a detailed study could be carried out to determine the level of resin from each species respectively. Microbial Exposure Table 3: Airborne Micobial Levels (CFU/litre) by area Area Mesophilic Mould Thermophilic Mould Thermophilus bacteria Sawmill 16,656 989 Nil Planer 856 16 Nil Lumber Yard 943 15 Nil Log Yard 4,379 6 Nil Outside Gate 658 8 Nil The results from the microbial analysis were tabulated in table 3. The highest exposure to both mesophilic and thermophilic mould was at the sawmill area. Second highest mesophilic mould exposure was at the log yard. The sawmill and log yard were places where a lot of wood dust was created. When the relative humidity increased in these two places, the wood dust became the best nutrition for mould growth. Meantime, there was no thermophilus bacteria detected in this factory during the study. Thus, there was not potential initiator for disease like pneumonia. But the high level of dust would definitely post respiratory hazards to the employees. Conclusions and Recommendation In short, the sawmill workers were exposed to a series of respiratory hazards caused by wood dust, resin acids and mould. This is especially serious at the areas like sawmill and log yard. The study on the respiratory health of the employee should be carried out to determine the exposure-response level. Below are a few recommendations to reduce the hazards which could be done by the sawmill: Supply outside air to the area with high dust exposure. Used of face mask during work. Reduce the relative humidity to less than 70% to prevent mould growth. Minimize used of compressed air to blown down for wood dust cleaning. References: Pengelly, M. et al (1994) An investigation into the composition of solder fume. Annal Occupational Hygiene 1984: (38)753-763. Read More