STSC Health Hazards and Hygiene 2 — Questions and Answers
Question 1: Silica dust exposure in construction is primarily associated with which occupational disease?
- Asbestosis
- Silicosis (Correct answer)
- Coal worker's pneumoconiosis
- Byssinosis
Correct answer: Silicosis
Crystalline silica dust causes silicosis, a progressive, irreversible lung disease, and is also a recognized carcinogen associated with lung cancer.
Silicosis is caused by inhaling crystalline silica dust generated during construction activities such as: cutting, grinding, drilling, or blasting concrete, masonry, sand, gravel, or stone. Silica particles lodge in lung tissue, causing fibrotic scarring that progressively reduces lung function. There are three types: chronic silicosis (10+ years exposure), accelerated silicosis (5-10 years), and acute silicosis (weeks to 5 years with very high exposures). OSHA's silica standard (29 CFR 1926.1153) sets an action level of 25 μg/m³ and a PEL of 50 μg/m³ as an 8-hour TWA.
Question 2: OSHA's construction standard for crystalline silica (29 CFR 1926.1153) requires engineering controls for tasks that generate silica dust. The most effective engineering control is:
- Requiring workers to wear N95 respirators
- Using wet methods or local exhaust ventilation (LEV) to capture dust at the source (Correct answer)
- Scheduling silica-generating work at night
- Posting 'Silica Hazard' warning signs around the work area
Correct answer: Using wet methods or local exhaust ventilation (LEV) to capture dust at the source
Wet methods (water suppression) and LEV capture silica dust at the source before it becomes airborne, providing the most effective protection.
OSHA's silica standard requires that, for specified tasks (Table 1), employers implement engineering and work practice controls. The most effective include: wet drilling (water suppression reduces dust generation by >90%); integrated water delivery systems on cutting saws and grinders; local exhaust ventilation (LEV) systems that capture dust at the point of generation; and enclosed cabs with HEPA filtration for equipment operators. Respirators serve as supplemental protection when engineering controls alone cannot maintain exposures below the PEL.
Question 3: Which of the following is a construction health hazard caused by repeated vibration exposure to the hands and arms?
- Carpal tunnel syndrome
- Hand-arm vibration syndrome (HAVS)/vibration white finger (Correct answer)
- Rotator cuff tear
- Cubital tunnel syndrome
Correct answer: Hand-arm vibration syndrome (HAVS)/vibration white finger
HAVS is caused by prolonged use of vibrating hand tools (jackhammers, grinders, saws) and causes damage to blood vessels, nerves, and joints in the hand and arm.
Hand-Arm Vibration Syndrome (HAVS), also known as vibration white finger, results from prolonged use of vibrating power tools (jackhammers, chipping hammers, grinders, chain saws). It causes: vascular damage (Raynaud's phenomenon — fingers turn white/blue in cold); neurological damage (tingling, numbness, loss of sensation); and musculoskeletal damage (loss of grip strength, joint damage). Prevention includes: using anti-vibration tools; limiting daily exposure time; using anti-vibration gloves; and health surveillance. HAVS is progressive and irreversible.
Question 4: What is the primary route of exposure that makes lead paint removal in construction a significant health hazard?
- Dermal absorption through the skin
- Inhalation of lead dust and fume (Correct answer)
- Ingestion through contaminated food
- Eye contact with lead-containing surfaces
Correct answer: Inhalation of lead dust and fume
Inhalation of lead dust or fume (from grinding, sanding, heating lead paint) is the primary exposure route in construction lead work.
When lead-based paint is disturbed during construction (abrasive blasting, grinding, dry sanding, open-flame burning, or torch cutting), lead particles become airborne as dust and fume. Inhalation is the primary exposure route in construction because these activities generate very fine particles that are easily inhaled deep into the lungs and absorbed into the bloodstream. Ingestion (hand-to-mouth) is a secondary route. OSHA 29 CFR 1926.62 requires air monitoring, engineering controls, respiratory protection, hygiene facilities, biological monitoring (blood lead levels), and medical surveillance.
Question 5: Heat illness prevention on construction sites primarily involves:
- Providing sunscreen to all workers
- Hydration (water every 15-20 minutes), rest in shade, and acclimatization for new workers (Correct answer)
- Scheduling all outdoor work before 6 AM
- Requiring workers to wear cooling vests at all times
Correct answer: Hydration (water every 15-20 minutes), rest in shade, and acclimatization for new workers
OSHA's heat illness prevention program focuses on water, rest, and shade — plus acclimatization for workers not yet adapted to heat.
OSHA's heat illness prevention strategy (applicable to construction under the General Duty Clause and state OSHA programs) emphasizes: Water — cool water near the work area, 1 cup every 15-20 minutes regardless of thirst; Rest — regular cool-down rest breaks in shaded or air-conditioned areas; Shade — accessible shade structures; and Acclimatization — gradually increasing workload and heat exposure for new workers over 7-14 days (the most critical factor, as 80% of heat fatalities occur in the first week of work in heat). Training supervisors to recognize heat illness symptoms is also essential.
Question 6: Adequate sanitation facilities on construction sites include potable water for drinking at a minimum rate of:
- 1 quart per worker per day (Correct answer)
- 1 quart per worker per 4-hour period
- 1 pint per worker per hour in heat
- 2 liters per worker per shift
Correct answer: 1 quart per worker per day
OSHA requires a minimum of 1 quart of potable water per person per hour during heavy work in heat, but baseline requirement is 1 quart per worker per day.
OSHA 29 CFR 1926.51 requires that an adequate supply of potable water be provided for drinking. The standard requires at minimum 1 quart per person per day (when not working in heat), but OSHA's heat illness prevention guidance recommends 1 cup (8 oz) every 15-20 minutes during heavy work in the heat — equivalent to approximately 1 quart per hour. Water containers must be clearly marked as potable, kept clean, and equipped with individual cups or fountains (common drinking cups are prohibited).
STSC Health Hazards and Hygiene 2
Silica dust exposure in construction is primarily associated with which occupational disease?