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IHMM CSMP practice questions

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Question 1Safety management

Under OSHA's Hazard Communication Standard, which document must employers make readily accessible to workers for each hazardous chemical in the workplace?

  1. The respiratory protection medical clearance
  2. The Safety Data Sheet Correct answer.
  3. The facility emergency action plan
  4. The process hazard analysis report

Explanation

HazCom requires employers to maintain a Safety Data Sheet for each hazardous chemical and keep it readily accessible to employees during each work shift. SDSs convey the 16-section hazard information that supports labeling and training obligations.

Question 2Safety management

A safety manager is establishing a hierarchy of controls for a noisy grinding operation. Which control strategy sits highest in the hierarchy?

  1. Eliminating the grinding task through process redesign Correct answer.
  2. Posting noise hazard signage
  3. Rotating workers to limit exposure time
  4. Issuing hearing protection to operators

Explanation

The hierarchy of controls ranks elimination and substitution above engineering, administrative, and PPE controls. Redesigning the process to remove the noise source is an elimination strategy and is therefore the most effective.

Question 3Safety management

Which of the following best describes the primary purpose of a job hazard analysis?

  1. To assign blame after an injury occurs
  2. To break a task into steps and identify hazards and controls for each step Correct answer.
  3. To determine the disciplinary consequences for unsafe acts
  4. To satisfy annual insurance audit documentation

Explanation

A job hazard analysis systematically breaks a job into sequential steps, identifies the hazards associated with each step, and defines controls before work is performed. It is a proactive risk assessment tool rather than an incident investigation or disciplinary process.

Question 4Safety management

An employee suffers a work-related injury that requires more than basic first aid but does not result in days away from work. Under OSHA recordkeeping rules, how is this generally classified on the OSHA 300 log?

  1. As a medical treatment case Correct answer.
  2. As a restricted duty case regardless of medical treatment
  3. As a fatality case
  4. As a first aid case only

Explanation

Injuries requiring medical treatment beyond first aid are recordable and are entered as medical treatment cases when no days away or restricted duty result. First aid cases are not recordable, and fatality classification applies only to work-related deaths.

Question 5Safety management

Which element is a required component of an employer's written Hazard Communication program?

  1. An inventory of finished goods awaiting shipment
  2. A copy of the corporate annual report
  3. A roster of employee home addresses
  4. A list of hazardous chemicals known to be present in the workplace Correct answer.

Explanation

The written HazCom program must include an inventory of hazardous chemicals known to be present, along with labeling, SDS, and training provisions. The chemical list is the foundation that ties labels, SDSs, and training together.

Question 6Safety management

In a permit-required confined space program, which duty belongs to the entry attendant?

  1. Testing the atmosphere before entry
  2. Maintaining a count of entrants and summoning rescue if needed Correct answer.
  3. Performing the initial hazard evaluation of the space
  4. Issuing the entry permit

Explanation

The attendant remains outside the space, tracks the number and identity of entrants, communicates with them, and summons rescue without leaving the post. Atmospheric testing and permit issuance are entrant and entry supervisor responsibilities.

Question 7Safety management

Which metric is commonly used to express injury experience as the number of recordable injuries per 100 full-time workers over a period?

  1. DART rate
  2. Lost workday severity rate
  3. Total case incidence rate Correct answer.
  4. Experience modification rate

Explanation

The total case incidence rate normalizes recordable injury counts to 100 full-time equivalent workers, allowing comparison across sites of different sizes. DART and severity rates address days away or restricted time, and the experience modification rate is an insurance pricing factor.

Question 8Safety management

A behavior-based safety process relies most directly on which activity to improve safe work practices?

  1. Disciplining workers who are observed at risk
  2. Observing behaviors, providing feedback, and reinforcing safe acts Correct answer.
  3. Posting monthly incident statistics
  4. Rewarding low reported injury counts

Explanation

Behavior-based safety uses structured observation of work practices followed by timely feedback and positive reinforcement to shape safe behavior. It depends on observation and coaching rather than punitive or outcome-based approaches.

Question 9Safety management

During a process hazard analysis, a team applies a guideword-based method to examine deviations from design intent in a covered process. Which technique is being used?

  1. HAZOP Correct answer.
  2. LOTO audit
  3. Root cause analysis
  4. Job safety analysis

Explanation

A hazard and operability study uses guidewords such as no flow, more pressure, or reverse flow to systematically examine deviations from design intent. It is a recognized PHA method for process safety management covered processes.

Question 10Safety management

A safety professional is calculating a total recordable case rate. The site recorded 12 recordable cases and 480,000 hours worked. Using the OSHA 200,000-hour base, what is the incidence rate?

  1. 2.5
  2. 5.0 Correct answer.
  3. 0.5
  4. 12.0

Explanation

The formula is (number of cases times 200,000) divided by hours worked. Twelve cases times 200,000 equals 2,400,000, and dividing by 480,000 hours yields 5.0 cases per 100 full-time workers.

Question 11Safety management

An investigation team wants to move beyond the immediate cause of a fall from a ladder. Which approach best identifies underlying management system deficiencies?

  1. Reviewing the ladder manufacturer's warranty
  2. Comparing the site's rate to the industry average
  3. Recording the injured worker's discipline history
  4. Applying a structured causal analysis such as the five-why or fishbone method Correct answer.

Explanation

Structured causal methods such as five-why analysis or cause-and-effect diagrams trace an incident back through contributing factors to root causes in management systems. They reveal deficiencies in training, planning, or oversight that a single immediate cause obscures.

Question 12Safety management

Which control measure is an example of an engineering control for a welding operation?

  1. Training welders on fume health effects
  2. Requiring welders to wear flame-resistant clothing
  3. Installing local exhaust ventilation at the welding point Correct answer.
  4. Rotating welders between tasks every two hours

Explanation

Engineering controls modify the workplace or equipment to reduce exposure at the source, and local exhaust ventilation removes welding fume before it reaches the breathing zone. Clothing, rotation, and training are PPE and administrative measures.

Question 13Safety management

In a lockout/tagout program, which step must occur before a machine is locked out for maintenance?

  1. Notification of affected employees and identification of energy sources Correct answer.
  2. Return of the machine to normal production
  3. Verification of isolation after energy control
  4. Removal of the lock by the maintenance worker

Explanation

Before applying locks, the authorized employee must understand the energy sources and notify affected employees of the impending shutdown. Verification of isolation follows lockout, and lock removal occurs at the end of the task.

Question 14Safety management

A safety manager is selecting leading indicators for a construction project. Which measure is a leading indicator?

  1. Workers' compensation claim costs
  2. Count of completed pre-task safety planning sessions Correct answer.
  3. Number of lost-time injuries
  4. Total recordable case rate

Explanation

Leading indicators measure preventive activities performed before harm occurs, such as completed pre-task planning sessions. Injury counts, incidence rates, and claim costs are lagging indicators that reflect outcomes already realized.

Question 15Safety management

Which practice best demonstrates management commitment as a foundational element of a safety management system?

  1. Assigning safety responsibilities only to the safety department
  2. Delegating all safety decisions to the safety committee
  3. Relying on posters to communicate safety priorities
  4. Having senior leaders participate visibly in safety activities and resource decisions Correct answer.

Explanation

Visible leadership participation and resource allocation signal that safety is a core value and shape worker behavior throughout the organization. Safety management systems depend on accountable leadership rather than delegation to a single function.

Question 16Safety management

An emergency action plan for a facility should address which of the following?

  1. Procedures for reporting emergencies and accounting for employees Correct answer.
  2. The annual capital budget for safety equipment
  3. Job descriptions for maintenance technicians
  4. Preferred suppliers for replacement equipment

Explanation

An emergency action plan must cover reporting procedures, evacuation routes, accounting for employees after evacuation, and rescue duties. These elements ensure orderly response and confirm that all personnel are accounted for.

Question 17Safety management

Which factor most directly determines the level of respiratory protection required for an airborne contaminant?

  1. The number of employees on the shift
  2. The exposure concentration relative to the assigned protection factor Correct answer.
  3. The age of the ventilation system
  4. The color of the respirator cartridge

Explanation

Selection depends on comparing the measured exposure concentration with the contaminant's exposure limit and the respirator's assigned protection factor. The chosen respirator must reduce exposure to at or below the applicable limit.

Question 18Safety management

A safety professional is designing training for adult workers. Which approach best reflects established principles of adult learning?

  1. Testing employees only on definitions from the written program
  2. Delivering a single lecture covering all policies at orientation
  3. Connecting content to learners' job tasks and allowing practice with feedback Correct answer.
  4. Relying on signed attendance sheets as evidence of competence

Explanation

Adult learners retain and apply information better when training is relevant to their tasks and includes hands-on practice with feedback. This approach builds competence rather than merely documenting attendance.

Question 19Safety management

Which element distinguishes a safety management system from a collection of standalone safety programs?

  1. A larger budget for personal protective equipment
  2. A documented system with defined policy, planning, implementation, evaluation, and corrective action Correct answer.
  3. A longer list of written procedures
  4. A higher number of posted warning signs

Explanation

A safety management system integrates policy, planning, implementation, evaluation, and corrective action into a continuous improvement cycle. Standalone programs lack this interconnected structure and feedback loop.

Question 20Safety management

A worker reports chest tightness and wheezing that improves on weekends away from a chemical process. Which exposure control priority should the safety professional apply first?

  1. Substitute the sensitizing agent or enclose the process to prevent exposure Correct answer.
  2. Provide the worker with additional break time
  3. Issue a respirator and continue the current process
  4. Schedule the worker for annual spirometry only

Explanation

Symptoms that improve away from work suggest a work-related sensitization, which calls for source controls such as substitution or enclosure. Reducing exposure at the source is more protective than relying on PPE or administrative measures.

Question 21Safety management

During a process hazard analysis, the team identifies a scenario in which a relief valve is undersized for a runaway reaction. Which recommendation category should be prioritized?

  1. Revising the operating procedure to reduce batch size
  2. Installing an independent high-temperature interlock and reviewing relief capacity Correct answer.
  3. Increasing operator training frequency
  4. Adding a warning sign near the reactor

Explanation

Inherently safer design and engineered safeguards such as independent interlocks and adequate relief capacity address the hazard directly. Administrative measures like signage, procedures, and training are less reliable for high-consequence scenarios.

Question 22Safety management

A site's total recordable case rate is stable, but near-miss reports have declined sharply over two quarters. What is the most defensible interpretation for a safety professional?

  1. The workplace has become inherently safer
  2. The lagging indicators confirm effective controls
  3. The decline proves training was effective
  4. The reporting culture may have weakened, masking ongoing risk Correct answer.

Explanation

Falling near-miss reports without a corresponding change in exposure often signal underreporting rather than reduced risk. A safety professional should investigate reporting barriers and verify whether hazards are being identified and corrected.

Question 23Safety management

An employer operates a covered process subject to process safety management. Which activity is required at least every five years for each covered process?

  1. Revalidation of the process hazard analysis Correct answer.
  2. Replacement of all pressure relief devices
  3. Recertification of every operator
  4. Reissuance of the emergency action plan

Explanation

PSM requires that each process hazard analysis be updated and revalidated at least every five years to confirm it remains current and accurate. Relief device replacement, operator recertification, and plan reissuance follow different schedules.

Question 24Safety management

An organization wants to integrate contractor safety into its management system. Which practice best reduces risk at the owner-contractor interface?

  1. Allowing contractors to self-manage all hazard controls
  2. Pre-qualifying contractors, aligning hazard controls, and coordinating site-specific orientation Correct answer.
  3. Relying on the contractor's injury rate as the sole selection criterion
  4. Requiring contractors to sign a general liability waiver

Explanation

Effective contractor management combines pre-qualification, shared hazard assessment, and site-specific orientation so that controls are coordinated across the interface. Injury rates alone are lagging and do not confirm control alignment.

Question 25Safety management

A safety professional is evaluating whether a control is functioning as intended after implementation. Which activity provides the strongest evidence?

  1. Reviewing the written procedure that describes the control
  2. Confirming the control was included in the budget
  3. Conducting periodic field verification and exposure monitoring Correct answer.
  4. Documenting the control in the training roster

Explanation

Verification through field observation and exposure monitoring confirms that a control actually performs as designed in practice. Written procedures and budget records document intent, not real-world effectiveness.

Question 26Industrial hygiene

In industrial hygiene practice, the primary purpose of an occupational exposure limit (OEL) such as an OSHA permissible exposure limit is to:

  1. Define the airborne concentration above which acute toxicity is guaranteed
  2. Specify the respirator class required whenever the substance is present
  3. Establish a legal or advisory ceiling intended to protect most healthy workers over a working lifetime Correct answer.
  4. Replace the need for exposure monitoring in general industry

Explanation

OELs are health-based values, adopted as legal limits or guidance, intended to protect the large majority of healthy adult workers from adverse effects across a working lifetime. They are not thresholds for guaranteed harm and do not by themselves dictate control technology or respirator selection.

Question 27Industrial hygiene

An 8-hour time-weighted average exposure is calculated by which approach?

  1. Using only the peak concentration recorded during the shift
  2. Summing all measured concentrations and dividing by the number of samples
  3. Averaging the highest and lowest concentrations measured during the shift
  4. Multiplying each concentration by its sampling duration, summing the products, and dividing by the total sampled time Correct answer.

Explanation

A TWA weights each concentration by the time spent at that level, so the products of concentration and duration are summed and divided by total time. This reflects cumulative dose rather than a simple arithmetic mean of samples.

Question 28Industrial hygiene

The hierarchy of controls places engineering controls above administrative controls because engineering controls:

  1. Eliminate the need for any personal protective equipment
  2. Remove or reduce the hazard at its source without relying on worker behavior Correct answer.
  3. Are always less expensive to install and maintain
  4. Require less documentation under OSHA recordkeeping rules

Explanation

Engineering controls such as local exhaust ventilation act on the source and do not depend on consistent worker action, which makes them more reliable than administrative measures. They are often costlier up front and may still require PPE as a supplement.

Question 29Industrial hygiene

A local exhaust ventilation hood captures contaminant most effectively when it is placed:

  1. At the worker's breathing zone on the downwind side
  2. Near the ceiling to capture rising hot air
  3. Downstream of the general dilution airflow in the room
  4. As close as practicable to the point of contaminant generation Correct answer.

Explanation

Capture velocity falls off rapidly with distance from the hood face, so proximity to the generation point is the dominant design factor. Positioning near the ceiling or downstream relies on dilution rather than capture.

Question 30Industrial hygiene

A substance assigned a skin notation in an exposure limit table indicates that:

  1. Cutaneous absorption can contribute significantly to total body burden Correct answer.
  2. Dermal exposure is impossible under normal handling
  3. The substance is a sensitizer only and has no inhalation hazard
  4. The substance is a confirmed human carcinogen

Explanation

The skin notation warns that absorption through intact skin may be a meaningful route of exposure, so air monitoring alone may underestimate dose. It does not mean the substance is exclusively a dermal hazard or that it is a confirmed carcinogen.

Question 31Industrial hygiene

Which of the following best describes the purpose of a workplace exposure assessment strategy such as that described in the AIHA guidance?

  1. To determine the exact number of workers who will develop disease
  2. To certify that a facility is permanently free of occupational health risk
  3. To characterize exposure profiles and support decisions about the adequacy of controls Correct answer.
  4. To satisfy insurance requirements for property coverage

Explanation

Exposure assessment characterizes the magnitude, frequency, and variability of exposures so that controls can be judged adequate and priorities set. It does not certify the absence of risk or predict individual disease outcomes.

Question 32Industrial hygiene

A material safety data sheet or safety data sheet is most useful to the industrial hygienist primarily because it:

  1. Certifies that the product has been tested for carcinogenicity
  2. Replaces the need for air sampling in all cases
  3. Provides the legally enforceable exposure limit for the substance
  4. Identifies hazard information, physical properties, and exposure controls to guide evaluation Correct answer.

Explanation

An SDS summarizes hazard identification, physical and chemical properties, and recommended exposure controls, which helps the hygienist plan monitoring and controls. It does not establish legal exposure limits or substitute for sampling.

Question 33Industrial hygiene

Which sampling approach is designed to collect the contaminant fraction that would penetrate to the gas-exchange region of the lung?

  1. Respirable particulate sampling Correct answer.
  2. Inhalable particulate sampling
  3. Total dust sampling by open-face cassette
  4. Thoracic particulate sampling

Explanation

Respirable samplers use a size-selective inlet to approximate the fraction of particles reaching the alveolar region, roughly those below about 4 micrometers. Inhalable and thoracic conventions target the nose and tracheobronchial regions respectively.

Question 34Industrial hygiene

A worker is exposed to 60 ppm of substance A for 4 hours and 20 ppm for the remaining 4 hours of an 8-hour shift. The PEL for A is 50 ppm as an 8-hour TWA. What is the 8-hour TWA exposure?

  1. 30 ppm
  2. 60 ppm
  3. 50 ppm
  4. 40 ppm Correct answer.

Explanation

The TWA equals (60 x 4 + 20 x 4) / 8, which is (240 + 80) / 8 = 40 ppm. This is below the 50 ppm PEL, though short-term or peak limits should also be checked separately.

Question 35Industrial hygiene

A contaminant has a PEL of 100 ppm. A worker's measured 8-hour TWA is 80 ppm while wearing a half-mask air-purifying respirator with an assigned protection factor of 10. What does the exposure indicate?

  1. The protected exposure is 80 ppm and the respirator is inadequate
  2. The exposure cannot be evaluated without a fit test record
  3. The protected exposure is about 8 ppm and is acceptable Correct answer.
  4. The respirator provides no protection because the PEL is exceeded

Explanation

The workplace exposure of 80 ppm divided by an assigned protection factor of 10 gives an estimated in-facepiece exposure of about 8 ppm, well below the 100 ppm PEL. The APF is a planning value, so program elements such as fit testing and medical clearance still apply.

Question 36Industrial hygiene

A solvent has an 8-hour PEL of 200 ppm and a 15-minute short-term exposure limit of 250 ppm. A worker performs a task for 10 minutes at 400 ppm. How should this be evaluated?

  1. Not acceptable, only if the 8-hour TWA also exceeds 200 ppm
  2. Not acceptable, because the 15-minute STEL is exceeded Correct answer.
  3. Acceptable, because the 8-hour TWA will likely remain below 200 ppm
  4. Acceptable, because the exposure lasted less than 15 minutes

Explanation

A 15-minute STEL applies to any 15-minute period, so a 10-minute excursion at 400 ppm exceeds the 250 ppm limit even though the full 8-hour TWA may be low. Both the TWA and the short-term limit must be satisfied independently.

Question 37Industrial hygiene

A substance has an OSHA permissible exposure limit but no OSHA action level. When does an employer's obligation to establish regulated-area and monitoring practices typically begin?

  1. Whenever employees may be exposed above the PEL Correct answer.
  2. Only when exposure exceeds the PEL by a factor of two
  3. Only when the SDS lists the substance as toxic
  4. Only after an employee files a complaint

Explanation

Where no action level is specified, the exposure limit itself serves as the trigger for required monitoring and related program elements. Complaints and SDS language do not define the regulatory trigger.

Question 38Industrial hygiene

When designing a local exhaust ventilation system, capture velocity is most appropriate as a design criterion when the contaminant is:

  1. Released as a buoyant vapor from an open heated tank
  2. Generated by evaporation from a large open surface with minimal air movement
  3. Emitted with significant momentum from a grinding operation Correct answer.
  4. Liberated as fine dust during manual sweeping across a wide area

Explanation

Capture velocity is used when contaminant is released with momentum and must be caught before dispersing, as with grinding or welding. Buoyant or diffuse sources are better addressed by other approaches such as enclosures or receiving hoods.

Question 39Industrial hygiene

A noise measurement of 90 dBA over an 8-hour shift is recorded. Using the OSHA 5 dB exchange rate, what is the permissible exposure duration at that level?

  1. 16 hours
  2. 12 hours
  3. 8 hours Correct answer.
  4. 4 hours

Explanation

Under the OSHA 5 dB exchange rate, 90 dBA is the 8-hour permissible level, and each 5 dBA increase halves the allowed duration. Thus 95 dBA would permit 4 hours, and 85 dBA would permit 16 hours.

Question 40Industrial hygiene

A worker's noise exposure is 95 dBA for 4 hours and 85 dBA for 4 hours. Using the OSHA exchange rate of 5 dB, what is the 8-hour TWA?

  1. 95 dBA
  2. 92 dBA
  3. 88 dBA
  4. 90 dBA Correct answer.

Explanation

Using the 5 dB exchange rate, 95 dBA for 4 hours equals a dose of 100 percent for that half shift, and 85 dBA for 4 hours equals 25 percent. Total dose of 125 percent corresponds to an 8-hour TWA of about 90 dBA.

Question 41Industrial hygiene

A heat stress assessment uses the wet bulb globe temperature index because it:

  1. Integrates temperature, humidity, radiant heat, and air movement into a single index Correct answer.
  2. Replaces the need for work-rate and clothing adjustments
  3. Directly measures core body temperature of the worker
  4. Measures only air temperature and ignores humidity

Explanation

WBGT combines natural wet bulb, globe, and dry bulb temperatures to reflect humidity, radiant load, and air movement. Work rate, clothing, and acclimatization are still applied through the associated exposure limits.

Question 42Industrial hygiene

An industrial hygienist finds that a solvent's measured airborne concentration is consistently 30 percent of its PEL, and the substance has a skin notation. What is the most appropriate conclusion?

  1. The skin notation is irrelevant because airborne levels are low
  2. Airborne exposure is below the PEL but dermal absorption may still add to the body burden Correct answer.
  3. Airborne exposure is adequately controlled and no further action is needed
  4. The exposure must be reduced to zero because a skin notation exists

Explanation

A concentration below the PEL addresses the inhalation route, but a skin notation signals that cutaneous absorption may contribute substantially to total dose. The hygienist should evaluate dermal contact and consider biological monitoring where available.

Question 43Industrial hygiene

Which statement correctly distinguishes a ceiling limit from a short-term exposure limit?

  1. A ceiling limit applies only to carcinogens, while a STEL applies to all substances
  2. A ceiling limit must never be exceeded at any time, while a STEL is a 15-minute average Correct answer.
  3. Both are identical in duration and application
  4. A STEL is an instantaneous value, while a ceiling limit is a shift average

Explanation

A ceiling is an instantaneous upper bound that should not be exceeded, whereas a STEL is averaged over a defined short period, typically 15 minutes. The two differ in duration and in how compliance is judged.

Question 44Industrial hygiene

A general dilution ventilation system is being considered for a solvent with a low PEL. Which condition most limits its suitability?

  1. The solvent is released at a steady, predictable rate
  2. The solvent vapor is lighter than air
  3. The room has adequate makeup air
  4. The solvent is highly toxic and requires tight control at the source Correct answer.

Explanation

Dilution ventilation relies on mixing and dilution and cannot reliably hold highly toxic substances to low limits near the source. Local exhaust or enclosure is preferred when toxicity is high or the PEL is low.

Question 45Industrial hygiene

Which of the following is the most appropriate first step when an employer receives an employee complaint about indoor air quality in an office building?

  1. Issue respirators to all occupants
  2. Immediately install HEPA filtration throughout the building
  3. Conduct a walkthrough and gather information on symptoms, timing, and building systems Correct answer.
  4. Sample for every possible volatile organic compound

Explanation

Indoor air quality investigations begin with systematic information gathering and a building walkthrough to identify patterns and likely sources before any sampling. Targeted sampling follows only when the walkthrough suggests specific agents.

Question 46Industrial hygiene

A substance is regulated with an 8-hour PEL of 1 ppm and a 15-minute STEL of 5 ppm. A worker's 8-hour TWA is 0.8 ppm, but a 15-minute sample during a task reads 6 ppm. What is the compliance status?

  1. Noncompliant, because the STEL is exceeded during the task Correct answer.
  2. Compliant, because the 8-hour TWA is below the PEL
  3. Compliant, because the STEL applies only to the shift average
  4. Noncompliant, because the 8-hour TWA exceeds the PEL

Explanation

The 8-hour TWA of 0.8 ppm is below the 1 ppm PEL, but the 15-minute result of 6 ppm exceeds the 5 ppm STEL. Each limit must be met independently, so the exposure is noncompliant.

Question 47Industrial hygiene

A worker exposed to a mixture of two solvents, each with its own PEL, has measured TWAs of 40 ppm for solvent A (PEL 100 ppm) and 30 ppm for solvent B (PEL 60 ppm). Assuming additive effects, what is the mixture exposure evaluation?

  1. The mixture ratio cannot be computed without knowing vapor pressures
  2. Only the component with the highest ratio needs to be evaluated
  3. The mixture is acceptable because each component is below its individual PEL
  4. The mixture exceeds unity and requires additional controls Correct answer.

Explanation

For additive effects, the fractions are summed: 40/100 plus 30/60 equals 0.4 plus 0.5, or 0.9. Values approaching or exceeding 1.0 indicate that the combined exposure is at or above the acceptable level and controls should be strengthened.

Question 48Industrial hygiene

A quantitative fit test yields a fit factor of 50 for a tight-fitting half-mask respirator. What does this result most directly indicate?

  1. The measured fit is adequate for the half-mask class, whose minimum passing fit factor is 100 only for full-facepieces
  2. The respirator provides an assigned protection factor of 50 in all workplaces
  3. The respirator should be discarded because any leakage disqualifies it
  4. The measured fit factor of 50 meets the commonly required passing level of 100 for half-mask respirators Correct answer.

Explanation

OSHA requires a minimum passing fit factor of 100 for half-mask tight-fitting respirators in quantitative fit testing. A result of 50 falls short of that criterion, so the respirator must be readjusted or a different size tried and retested.

Question 49Industrial hygiene

An employer uses a substance with an OSHA PEL and an action level of half the PEL. Exposure monitoring shows an 8-hour TWA above the action level but below the PEL. What is the most likely regulatory consequence?

  1. The employer must immediately cease the operation
  2. Only medical surveillance is required regardless of exposure duration
  3. No obligations arise until the PEL itself is exceeded
  4. Periodic monitoring and other program elements triggered by the action level apply Correct answer.

Explanation

An action level is a trigger below the PEL that activates requirements such as periodic monitoring and, depending on the standard, medical surveillance or training. Exceeding the action level does not generally require shutting down the operation.

Question 50Industrial hygiene

A ventilation system's duct velocity is found to be well below the recommended transport velocity for a dust with high settling tendency. What is the most likely operational consequence?

  1. Reduced fan power consumption with no adverse effect
  2. Dust accumulation and possible duct blockage Correct answer.
  3. Increased capture efficiency at the hood face
  4. Improved dilution of the contaminant in the workspace

Explanation

Transport velocity must be high enough to keep particulate suspended; if it falls too low, dust settles in the ductwork and can cause blockage or re-entrainment. Capture efficiency is not improved by inadequate transport velocity.