1. Explain different types of hazards (physical and biological agents) and their effects and doseresponse

Transcription

1 UNIT V STUDY GUIDE Recognition of Hazards (Part 2: Physical Agents) Course Learning Outcomes for Unit V Upon completion of this unit, students should be able to: 1. Explain different types of hazards (physical and biological agents) and their effects and doseresponse relationships. 2. Contrast sampling for noise, radiation, and thermal stress. 3. Describe the elements of an exposure assessment program for physical and biological agents. 4. Explain the process for determining if an exposure is acceptable or unacceptable. Reading Assignment Chapter 9: Industrial Noise Chapter 10: Ionizing Radiation Chapter 12: Thermal Stress Unit Lesson Physical agents make up a group of occupational health hazards that include noise, vibration, ionizing and nonionizing radiation, and thermal stress. Noise According to OSHA: Noise, or unwanted sound, is one of the most common health problems in American workplaces. The National Institute for Occupational Safety and Health (NIOSH) estimates that 30 million workers in the U.S. are exposed to hazardous noise. Exposure to high levels of noise may cause hearing loss, create physical and psychological stress, reduce productivity, interfere with communication, and contribute to accidents and injuries by making it difficult to hear warning signals. (n.d.) Noise can produce both temporary and permanent hearing loss, or a combination of temporary and permanent hearing loss. The loss can be irreparable if caused by high intensity noise over a long period of time. To prevent noise-induced hearing loss, an employer should implement a hearing conservation program (HCP) that includes the identification of high noise areas, training of employees, and medical monitoring under the direction of a physician. Noise is a stressor that needs to be evaluated along with chemicals. Noise can be found in most occupational environments. The Occupational Safety and Health Administration has a standard that addresses hearing health (29 CFR ). OSHA s website describes these requirements as follows: OSHA requires employers to determine if workers are exposed to excessive noise in the workplace. If so, the employers must implement feasible engineering or administrative controls to eliminate or reduce hazardous MOS 6301, Advanced Industrial Hygiene 1

2 levels of noise. Where controls are not sufficient, employers must implement an effective hearing conservation program. (n.d.) Noise has triggers, just like chemical exposures. A properly calibrated dosimeter will provide you with the information that you need to determine if an HCP is needed and if you are in compliance with regulations. When exposures are between dba-twa (90 db thresholds), the employer must evaluate the "feasibility" of implementing noise controls. When exposures are >100 dba-twa, the employer must implement feasible engineering or administrative controls to reduce noise. OSHA 29 CFR Specific Trigger Points: PELs (5 db exchange, 80 dba threshold) Table G-16 & G16-a o 90 dba 8 hr. TWA o 85 dba 8 hr. TWA (action level) implement a hearing conservation program o 115 dba 15 minutes o 140 dba Ceiling Engineering/Administrative Controls o dba-twa (90 dba threshold): Evaluate o Above100 dba-twa (90 dba threshold): Implement In order to determine which of the elements above apply to a facility, a sound level survey and employee exposure assessment is necessary. Initial Monitoring Requirements o Sound level survey to characterize area sound levels o Dosimetry to characterize employee exposures Follow-up Monitoring Requirements o Within 90 days of process or equipment change (where the anticipated noise levels will increase) o Every five years Sound level survey Dosimetry (only required for job classifications where sound levels have significantly increased. e.g., greater than 3 dba) Types of Noise Monitoring Equipment Sound Level Meter (SLM) Noise Dosimeter Octave Band Analyzer Human Ear Human response to noise is an excellent initial screening tool to indicate that additional monitoring may be needed. Perhaps an explanatory sentence here to help the student understand this is needed. There are many types of SLMs Type 0 - Lab Standard Type 1 Precision Type 2 - General Purpose - what we have Type S - Special Purpose MOS 6301, Advanced Industrial Hygiene 2

3 The industrial hygienists will still need dosimeter data to accurately define employee exposures. Calibration must always be completed - PRE and POST measurements. The calibrator must be serviced on an annual basis by the manufacturer. Documentation is critical. If you do not have documentation of the calibration and annual service, an assessment will not be valid. Most dosimeters today can also function as a SLM. As a result, industrial hygienist no longer needs to buy both. Costs are around $ per unit. Dual function noise dosimeters can measure the following: Measures TWA exposure Microprocessor Technology o 8-hour TWA o Peak sound levels o Histograms Dose (%) versus TWA (dba) Noise reports may present results in units of dose (%) or TWA (dba). This formula shows you how to convert between them. Noise dose is a percentage of the PEL o 100 % = 90 dba o 50% = 85 dba Conversion: TWA = log (Dose/100) + 90 o To convert 70% dose to TWA TWA = log (70/100) + 90 TWA = 87 dba How to Conduct a Sound Level Survey: Obtain a map of the facility (an Emergency Evacuation Plan works well) Calibrate the SLM Collect sound level measurements with an SLM at employee workstations (other areas as needed) Explain to employees what you're doing Obtain process/production information Calibrate the SLM Noise SLM surveys should be updated every time there is a change in process equipment or a significant, permanent change is processed. Using a sound level survey, walk around the facility and record the noise levels. A simple hand drawn map will be sufficient. However, if you would like to be more professional, you can use simple mapping software. Figure 10 shows an example: MOS 6301, Advanced Industrial Hygiene 3

4 Dosimetry Is Needed When: Figure 10. Example Diagram for a Sound Level Survey. (AIHC, 2012) Employees are mobile Machines cycle on/off and rates change o Paper machines, winders o Planer, trimmer, debarker o Fork trucks, palletizer, conveyors, o Knuckle booms, loaders, diesels Noise sources are not continuous Some jobs may not need dosimetry, if the employee is in the same area for extended periods of time (> than 60 min.), then the exposure can be calculated using an SLM. Once you have completed your SLM noise survey, and have reviewed the data, you will need to determine if noise dosimetry is needed. OSHA requires that you identify employees with TWA exposures above 85 dba to include in a hearing conservation program. The best way to accomplish this is using dosimetry. How To Conduct Noise Dosimetry: Identify similarly exposed employees Monitor employees for at least seven hours Explain to employees what you re doing Record employee/process information on the exposure forms Calibration!! For employees working extended shifts (10 or 12 hours) we recommend that you still conduct seven hours of exposure monitoring but try to capture the noisiest part of the shift. The OSHA PEL for a 12-hour shift is 82 dba and for 10-hour shift is 83 dba. If you identify employees with TWA exposures to noise above 90 dba, OSHA requires that hearing protection be used. For TWA s above 100 dba, OSHA requires an employer to investigate feasible engineering controls to reduce exposures. For a hearing conservation program to be effective, employee participation is essential. MOS 6301, Advanced Industrial Hygiene 4

5 Workers must properly wear hearing protection in all high noise areas or they will not provide the desired level of protection. Without worker cooperation, the program will not succeed! Radiation As previously mentioned, almost all workplaces will have noise hazards to control. A much smaller number of workplaces will have to deal with radiation hazards. Chapter 10 in our textbook will cover the typical issues related to ionizing radiation. Ionizing radiation is a term for charged particles that are capable of knocking electrons out of their shell. If the cells are in the human body, they can produce significant cellular damage. The potential damage from ionizing radiation depends on the type of particle. Below are some examples: Ionizing Radiation o Produces changes (ionizations) in biological systems Types of Ionizing Radiation o Alpha (can t penetrate the skin) Radon-226, Polonium-210 o Beta (stopped by a thin sheet of metal) Krypton-85, Stronium-90 o Gamma (high energy, more penetrating) Cobalt-60, Cesium-137 Some typical industrial sources are radiation include, but are not limited to the following: Pipe/Equipment Scale (Naturally Occurring Radioactive Materials [NORM]) o scale (Radon-226 alpha, and possibly Strontium-90 beta) Density Gauges o Accuracy/K-Ray thickness gauge (Krypton-85 beta) Level Gauges o tank level gauges (Cesium-137 gamma) Electron Beam Dryers o x-ray producing equipment The regulatory environment for radiation sources is very complex. Regulators include the Federal Nuclear Regulatory Commission (NRC) and various state agencies in agreement states. Regulatory requirements include: Regulate Radiation Sources License of Sources o General vs. Specific Permissible Occupational Dose Limits o 2 mrem/hour (whole body: head, trunk, arms, legs) o 100 mrem/year (whole body) Notice To Employees There are two types of radiation licenses issued: Specific License: A specific license is granted to the company where the device is installed. For example, the company owns the source. General License: A general license is granted to the manufacturer, and the manufacturer retains ownership of the source. Each license will specify requirements that the facility must meet as part of their radiation safety plan. These include the following items/activities: Physical Inventory o Every 6 months (or as specified by the state/license) o Name of person performing inventory, Date, Isotope, Activity, Source Manufacturer, Serial Number Maintenance Test o Wipe Test (every 6 months or as specified by the state/license) MOS 6301, Advanced Industrial Hygiene 5

6 o Not required for radioactive gases WHY? Because a gas will quickly escape and will not linger in the workplace. Shutter Test (every 6 months or as specified by the state / license) The permissible occupational dose limits are for an Unrestricted Area are always expressed as a whole body. Restricted Area permissible occupational dose limits will have specific limits for extremities, skin, eyes, etc. The restricted area is established to control exposure (don t confuse this with a radiation area). A radiation area is an area where the radiation in the area measures 5 mrem/hour at a distance of 12 inches from the source. Radiation signs are required for: Radiation Area vs. Radioactive Material Radiation Area o 5 mrem/hour at 12 inches from the source Radioactive Material o Contains a radioactive material Figure 11. Radioactive Materials Sign (RPC Physics, 2010) Thermal Stress Thermal stress is the generic term used for both heat and cold stress. Chapter 12 in our textbook provides a detailed review of these hazardous health conditions. Thermal stress may involve heat stress or cold stress. Heat stress (increase in core temperature) Cold stress (decrease in core temperature) Cold stress effects include hypothermia, frostbite, and Raynaud s Syndrome (White Fingers). Hypothermia symptoms include: Shivering Sensation of cold Slow irregular heartbeat Weak pulse Blood pressure changes To prevent cold stress, you should implement the following controls: Wear appropriate clothing Remove wet clothing Protect workers from drafts Provide for employee acclimatization Provide awareness training Heat stress includes: heat rash, heat collapse, heat cramps, heat exhaustion, and heat stroke. Symptoms of heat exhaustion include: MOS 6301, Advanced Industrial Hygiene 6

7 Headache Nausea Dizziness Weakness Thirst Giddiness To prevent heat stress, you should implement the following controls: Provide for fluid replacement Limit diuretic intake Provide adequate rest periods Provide personal protective equipment Provide for employee acclimatization Provide awareness training Both heat and cold extremes represent a potential hazard to workers. Humans can learn to work and live in both hot and cold climates and conditions. Providing awareness training and providing for adequate acclimation, in addition to proper PPE and work/rest regimens, can be very effecting in controlling the potential risks. References Bullock, W. (2012). Example Diagram of a Sound Level Survey [Figure 10]. Retrieved from paper presented at the American Industrial Hygiene Conference, Portland, OR. Occupational Safety and Health Administration. (n.d.). Noise and hearing conservation. Retrieved from: Radiological Physics Consultants. (2010). Radioactive Materials Sign [Figure 11]. Retrieved from: Suggested Reading Occupational Safety and Health Administration. (n.d.). Noise and hearing conservation. Retrieved from MOS 6301, Advanced Industrial Hygiene 7