In the event that you do not identify the correct answer, if you show your work and how you arrived at your result, you may receive partial credit. However, if you do not show your work and the answer is not correct, zero credit will be given for that problem.
1. Suppose the sound pressure level of each of three individual noise sources is measured at a point such that with each source running individually, the sound pressure is as follows:
Source 1 - 88 dB
Source 2 - 86 dB
Source 3 - 91 dB
What is the sound pressure level with all three running? (Show your work).
2. A compressor in a mechanical room was measured at 8 feet from the source to have a sound pressure level of 92 dB. What would the sound pressure level be at 16 feet from the source?
3. A compressor in a mechanical room was measured at 8 feet from the source to have a sound pressure level of 92 dB. What would the sound pressure level be at 4 feet from the source?
4. A compressor in a mechanical room was measured at 8 feet from the source to have a sound pressure level of 92 dB.
a. If a second identical compressor was placed immediately next to the first, what would the resulting sound pressure level measurement at 8 feet be?
b. If a third identical compressor was placed immediately next to the first two, what would the resulting sound pressure level measurement at 8 feet be?
5. A mechanic must work in an area where three air-handling units are present. Each air handling unit individually generates a sound level of 95 dB at 5 feet from the source.
a. If the worker is positioned 20 feet from the first source, 10 feet from the second source, and 5 feet from the third source, and all three units are running continuously, to what sound level is the worker exposed? Show all your work.
b. If the unit 20 feet from the worker is turned off and the other two are running, to what level is the worker exposed?
c. If the unit 5 feet from the worker is turned off and the other two are running, to what level is the worker exposed?
d. Assuming all units are running and the worker's job requires him or her to stay in that location (20 feet from the first source, 10 feet from the second source, and 5 feet from the third source)for 4 hours and work in another location with exposure below 65 dBA for the remaining 4 hours, what is the 8 hour TWA of the exposure of the worker?
i. Does the employee need to be included in a hearing conservation program?Why or why not
ii. Does the employee need hearing protection?Why or why not?
iii. If the worker does not have a threshold shift, under OSHA, to what level must an employer attenuate exposure?
iv. If the worker has a threshold shift, under OSHA, to what level must an employer attenuate exposure?
v. Identify at least one engineering, one administrative, and one protective equipment control that could be implemented by the employer to reduce the worker's exposure.
vi. If the employer chooses to use protective ear plugs with an NRR rating of 25, to what level (using the OSHA Technical Manual and Oregon OSHA method) would the hearing protection attenuate the exposure?
6. If an employee is exposed to continuous sound levels for 3 hours at 94 dB and is then exposed to sound levels of 80 dB for the rest of the 8-hour day, what is the employees' 8 hour TWA in dB using OSHA's calculations?
a. Does this employee exceed OSHA's PEL?
b. Does this employee need to be in a hearing conservation program?
7. An employee is working with a jackhammer that causes significant vibration in the hands and body. Identify at least three potential health effects associated with exposure to this kind of vibration?
8. Identify at least three methods of minimizing the effects of vibration on a worker.
9. Given the following measurements taken in direct sunlight:
Globe Temp (F) 94
Dry Bulb Temp (F) 91
Natural Wet Bulb Temp (F) 83
a. What is the calculated WBGT in degrees Fahrenheit?
b. What is the calculated WBGT in degrees Celsius?
c. What is the ACGIH range of recommended percent of work in a one to two hour cycle for moderate work for acclimatized workers?
d. What is the ACGIH range of recommended percent of work in a one to two hour cycle for light work for unacclimatized workers?
10. Given the following measurements taken in the shade:
Globe Temp (F) 92
Dry Bulb Temp (F) 95
Natural Wet Bulb Temp (F) 88
a. What is the calculated WBGT in degrees Fahrenheit?
b. What is the calculated WBGT in degrees Celsius?
c. What is the ACGIH range of recommended percent of work in a one to two hour cycle for moderate work for acclimatized workers?
11. Given the following measurements:
Botsball reading: 81 (F)
Dry Bulb Temperature: 86 (F)
a. What is the calculated WBGT in degrees Fahrenheit?
b. What is the calculated WBGT in degrees Celsius?
c. What is the ACGIH range of recommended percent of work in a one to two hour cycle for light work for unacclimatized workers?