Frequency range : GHz – 20. GHz ii. Sound pressure: 0,00002 N/mm – 200 N/mm 2. Describe the equation used for the calculation of sound pressure level. What is the unit used to express SSP? It is a logarithmic ratio between a measured quantity and the reference and the threshold of hearing. SSP-guppy Unit is db (decibel) 3. Give meanings to these terms: i. A-weighting network: a calculation algorithm included in sound level meters that targets some frequencies more than others. A network is specific in calculating occupational noise exposure. Ii.
Exchange rate: is a method the allowed exposure time when the exposure level increases under a given criterion level. Ii. Criterion level: it’s the level permitted for a full 8-hour work shift per day. 4. Name the factors that affect the degree and extent hearing loss. Among these, which of them are considered in the setting of occupational noise exposure criteria? Intensity of noise Frequency characteristics of noise Duration of exposure per day Total work duration Individual susceptibility Age of the worker Coexisting hearing loss and ear disease Non-occupational noise exposure 5.
Briefly explain these performance characteristics of a sound level meter: i. Type 1 and 2: type 1 is for precise measurements in the field and type 2 is general repose measurements ii. Slow/Fast/Peak response: the slow meter response uses an average time constant of one second; fast meter response uses an average time constant of O. 125 second. Peak is used for impact noise and uses an average of 20 to 50 sec and will display the peak noise. Iii. Leg: is the measure of percent noise dose or time-weighted average level over the sampling period 6. Briefly explain the purposes of noise level measurements using i.
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Dosimeter: Dosimeter is usually worn by the worker for long period of time to determine the personal exposure compared to exposure criteria. Ii. Octave band analyzer: it is usually used for noise measurements related to hearing conservation and noise abatement purposes. 7. Describe how area noise measurement results are used in occupational noise assessment. It is used to determine the presence of a noise hazard, prepare a noise map, analyze areas where engineering controls are required and define areas where hearing protection is required 8. Describe how personal noise measurement results are used in occupational noise assessment.
It is used to determine the degree of personal noise exposure and compliance with applicable exposure limits, to evaluate appropriate control assures and provide data for the training and instruction of workers 9. Name three noise control measures pertaining to: i. Engineering controls: changing the method of processing, add an enclosure to the noise SOUrce and evaluate/change the acoustical design of the machinery. Ii. Hearing protection: supply of appropriate types of hearing protection, designation of mandatory hearing protection areas and posting of signs regarding hearing protection 10.
Explain these terms: i. Audiometric testing: testing done to determine the hearing thresholds of a person. Ii. Audiogram: a report or graph that shows the earring threshold assured in each ear at the specified test frequencies. II. Numerical and Essay Questions (1% of total course mark) 11. The sound levels generated by four machines are tested individually and recorded the following results: Machine A: 97 dab; Machine B: 89 dab; Machine c: 92 dab; Machine D: 101 dab. What is the expected sound level when all four machines are operated simultaneously in the same area.
Machine A (97) – Machine B (89) = 8 Add 1 db 98 db- 89 db -9 99 db -92 = 7 100 db- 101 = 1 Add 3 db Total is 1 03 db when the machines are operated simultaneously in the same area 12. A noise dosimeter is set to measure noise using the criteria of 85 dab for 8 hours, 3 dab exchange rule. What is the TWA sound level in dab, when, at the end of the 8 hours measurement, the dosimeter gives dosage readout of 800%? 85 dab for errs = 100% 88 dab = 200% 91 dab 400% 94 dab = 800% The exposure condition is 94 dab for the 8 hours measurement. 3. A noise survey was conducted to assess a worker’s noise exposure for the purposes of determining compliance with the COACH noise TTL. A) Outline the type of instrument and instrumental settings required for this survey. The instrument must meet specified ANSI standards. It must be a Type 2 sound measurement device and allow measurement of A-weighted sound with a slow meter response b) This survey found that the worker was exposed to noise in the following three areas over his 7. 5 hrs. Per day work shift.
Area – Duration Levels Recorded (dab) A -5 hrs 85 B. 1. 5 hrs 91 C -IR 82 Comment on whether the worker’s exposure is excessive or not and give reasons to support your conclusion. Calculation: (CIA/IT + CO/TO + 100 – % (5/8+ 1. 5/2 + 1/16) (0. 625 + 0. 75 + 0. 0625) * 100 = % 1. 4375 * 100 = 144% of exposure limit This is well above the exposure limit allowed even if the exposure time of the ark shift is only 7,5 hours. Part B: Module 11 – Ventilation 14. Briefly explain the four reasons of providing ventilation in a workplace.
To supply fresh air containing oxygen to a work space To promote worker comfort by controlling heat, humidity, suppressing doors and maintaining acceptable air quality To control possible contaminants by dilution or removal of the contaminant To control flammable or explosive concentration of air contaminants hence reducing fire or explosion hazard 15. Explain the relationship between the air capacity observed at a given ventilation system and the air pressure within the ductwork of the ventilation yester.
Air pressure in a ventilation system is usually created by a fan. Increase pressure will make the air move within the system. The mass of air remains the same, the velocity of the air will be in relationship with the amount of pressure applied and the air conditions (temp, humidity and barometric pressure) 16. Briefly explain the three applications of dilution ventilation in workplace health and safety. Control of air contaminants: Dilution ventilation mixes contaminated air with clean air, hence lowering the concentration of contaminants.
Control of explosion and fire hazard: dilution ventilation will educe the concentration of flammable gases/vapors within an enclosure below the acceptable limits Control of heat and humidity: is provided to prevent a build-up of heat and/or humidity from work processes. 17. What does HAVE stand for? How does HAVE system improve air quality? Heating, Ventilation and Air-Conditioning. HAVE system are designed to control the air supplied to the occupied space. 18. Name the five basic components of a local exhaust ventilation system.
Use two to three sentences to describe the functions of each component. A hood or enclosure, to contain, collect or receive the air contaminants Duct work to rainspout air and air contaminant An air cleaning device both to remove harmful contaminant and pollution An air moving device to produce airflow that moves the air in the system A stack to disperse the contaminants to the ambient air 19. Briefly describe the three basic local exhaust hood designs. Give an example of each of these types of hood in the workplace. Enclosure hoods.
They normally surround the point of emission of contaminants as completely as possible (ex. Laboratory fume hood) Receiving hood. They are designed to receive the emission which has some initial velocity imparted to it by the emitting source (ex. Canopy hood) Capturing Hood. They capture the air contaminants generated from outside the hood itself (ex. Flexible duct external hood in welding operation) 20. Describe the two types of hood air velocity measurement that are important in describing the exhaust characteristics of an exhaust hood and explain why.
Capture velocity: air velocity in front of the hood that is required to overcome opposing air current. Face velocity is the velocity of air at the hood opening 21. What is air resistance within a duct? How does air resistance affect ventilation system performance? Give three examples as to how air resistance can be minimized. Air resistance causes drop in capacity of the ventilation system. It has two main causes: Friction and turbulence. Turbulence is caused by duct screen, entry ports, angles and branches in the ducts.
Friction is caused by the air coming in contact between the air ventilation components like air cleaner, filter, the material used for the ducts. To help maximizing the efficiency of the duct system, the duct runs must be as short as possible, as straight as possible and elbows should have a wide radius to prevent turbulence. 22. Name three useful applications of smoke tube tests. It shows the pattern of contaminant dispersion It help to identify air movement and direction in a closed space and the effects of cross drafts It indicates whether an area is under positive or negative air pressure 23.
Explain the similarities and differences of these three devices: a) Swinging vane anemometer: b) Thermal anemometer c) Pivot tube The three of them are used to measure air velocity. Both the Swinging vane and thermal anemometer requires calibration before being used. Both the swinging vane and Pivot tube are using air pressure to measure velocity, and the thermal anemometer used the variance in electrical resistance. The Pivot tube is insider a primary standard for measurements of air velocity in ducts. II.
Essay and Numerical Questions (1% of total course mark) 24. Using a table, compare and contrast the advantages and disadvantages of using “Dilution Ventilation” versus “Local Exhaust Ventilation” in occupational health. Dilution Ventilation Local exhaust ventilation Installation cost Much Lower (and equipment is also less costly) Specific application may be very costly Energy cost Requires large volume of air to be efficient, increasing cost Lower amount of air moved, decreasing the cost Flammable and dangerous gases elimination
It dilutes the gases efficiently, but cannot handle large quantities of air contaminant or highly toxic air contaminants Very efficient because of capture at the source, and removal from the environment Control of air quality (humidity and temperature) Very effective Not able to control these parameter Effective against particles of specific processes generating contaminant irregularly Ineffective, and also inefficient against surges in contaminant if the process is irregular Can handle all types of contaminants including dusts and metal fumes and is the only choice for highly toxic contaminants Maintenance Simple to maintain
Regular maintenance, cleaning and inspection is required 25. A Pivot tube is used to measure the air pressure at a point of a ventilation duct. The following are recorded: TAP = 0. 9 “w. G. SP = 0. 2″ w. G. Given that air is at standard conditions: 70 OF, 29. 92” Hag, air density Calculate the duct velocity. 0. 9-0. 2 UP = 0. 7 w. G. Velocity = MM Velocity = 400507 Velocity = 4005*0. 837 Velocity = 3352. 2 CFML Note: Report the calculated value in three significant figures Part C: Module 12 – Lighting I. Short-Answer Questions (2% of total course mark) 26. Briefly explain the five reasons for providing lighting in a workplace.
To acclimate the completion of visual tasks To reduce eye fatigue and related symptoms To provide a sense of well-being and comfort To enhance productivity by reducing error related to visual tasks To provide visibility for safety consideration 27. What is “Luminance”? What are the units used to describe luminance. The word luminance refers to the amount of light that falls on any surface. It is calculated in lug (lax)for the SSL system and in footfall (FCC) in the English system. 28. Name the organization that makes recommendations about luminance for workplaces. The Illuminating Engineering Society of North America (SEES) 9.
What general factors are considered in the prescription of luminance requirements in a workplace? What are the tasks? What is the visual environment? How much time is spent on task? How important is the task How important is accuracy How important is speed How difficult is the task (visually) What are the age (or average) of the workers 30. What does “Quality of Illumination” mean? It refers to alighting condition that all luminance contribute favorably to visual performance, visual comfort, ease of seeing, safety and aesthetics for the specific visual task. 31. What is “Luminance? What are the units used to describe luminance.
It refers to the amount of light emitted or reflected from any surface such as a light fixture or object. The unit in the SSL system is candela per square meter (CD/mm) and in the English system it’s the foot-Lambert (FL) 32. Explain the meaning for each of these terms: Luminance distribution: is the distribution of luminance of the task/object and the surroundings and its effect on the eye function. Discomfort glare: is the sensation of discomfort or annoyance felt when the level of light are greater than the level which the eye have adapted, but performance of visual task is till possible.
Disability glare: levels of light to high for to maintain the ability to discern objects in the visual field. Reflectance : It is a ratio calculated by dividing the amount of light falling on a surface by the amount of light reflected from the same surface. Veiling reflection : It is caused by reflected glare is produced within the visual task itself. Luminance : Is defined by the complete lighting unit (the lamp or lamps, with the parts designed to distribute, position and protect the lamp. 33.
Briefly describe three workplace design considerations that would affect the quality of lighting in a workplace. The room dimensions are important, as large rooms need more light. Colors and reflectance of the surfaces (walls, floors, ceiling) as a direct effect on light distribution General lighting (how many luminance, what type of lamps, how they are mounted and what type of reflector/ diffuser are installed 34. Briefly describe three aspects of a lighting maintenance program. Regular inspection: that component should include general condition inspection, old lamps replacement as needed.
Regular cleaning: The general environment should be clean regularly as dust and other debris may reduce the efficiency f the luminance and clean surfaces increase the lighting output of the visual environment. Adequate record keeping of all maintenance activities would help in identifying problem areas, faulty equipment and could be used in planning. Part D: Module 13 – Biological Monitoring 35. What is “Tectonics’s” and how does it relate to biological monitoring? It is the study of absorption, distribution, metabolism, beatifications, accumulation and excretion/elimination of taxicabs in the body.
We need to have proper knowledge of tectonics’s to properly evaluate the exposure through all routes. To monitor possible exposure/accumulation, to monitor the efficacy of engineering controls and personal protection measures and to evaluate exposure in retrospect. 36. Briefly explain the purposes of biological monitoring. Give an example in each case. It provides a measure of a worker individual response to exposure. It also represent the worker work practices, physiological characteristics and provide information about exposure through all possible routes. 37. What are the four basic types of biological monitoring measurements?
Give an example in each case. The amount of the chemical in blood or urine: By lab analysis, checking lead in blood. The amount of metabolite in a biological media: testing for hipper acid in urine to assess toluene exposure The concentration of gases in exhaled air: testing for CO in exhaled air of workers exposed to it. The amount of change of a characteristic endeavors biological or biological change induced by the chemical. A good example is the depression of cholinesterase activity as a result of exposure to some pesticides (archbishoprics compounds) 38. Briefly explain the similarities and differences between TTL versus BEE.
BEE is an index of a worker’s internal dose of the agent of concern through ALL possible out of absorption, as TTL are airborne level. BEE are related directly to the development of adverse effects. 39. What are the three common types of biological specimen used in biological monitoring? Use two to three sentences to summarize the characteristics of each. Exhaled air: this sample is suitable for volatile, stable and/or hydrophobic types of determinants. It is considered a non-invasive monitoring technique. Blood samples: Blood sampling measurements are suitable for most determinants.
One of the issue is that the determinant may be distributed unevenly in all the blood constituents. It should be clear when doing blood analysis which component of blood must be analyses. Urine samples: Urine is most suitable for measurements of hydrophilic chemicals, metals and metabolites. It can be a direct measurement, or as a proportion with creating. The main disadvantage is the variability of urine output. Urine is a non-invasive sampling method 40. Regarding the BEES for each of these chemical agents: CO, lead, and parathion. Describe their: a. Determinants: b. Sampling time and implications c.
Notations, footnotes, and implications Chemicals Determinant(s) Sampling time Notations co Chronologically CO in exhaled air End of shift CO is eliminated rapidly, hence the need to sample as soon as possible after exposure B, NSA CO may be present in non-occupational environment (background). In addition, it can be present in the sample because of other chemicals hence the Non- Specificity of the results Lead Lead in blood Not critical (lead is present and still will be hours/days after exposure) None Parathion Total p-interpretation in urine NSA Specificity of the result 41.
Briefly summarize the advantages and useful applications of using biological monitoring as a tool of occupational exposure assessment. It provides a more accurate assessment of adverse health effects compared to air monitoring from substances that exert their toxicity after entering the body It takes into consideration exposure from all routes (inhalation, ingestion and absorption) It can monitor the effectiveness of personal protective measures It may help in monitoring the adequacy of personal hygiene practices.
It takes into account the variability and sensitivity of the individual worker It helps to identify proper medical treatment following an acute or emergency exposure 42. Briefly summarize the disadvantages and limitations of using biological monitoring as a tool of occupational exposure assessment.
