OHST cheat sheet

OSH Act Section 5(a)(1), the General Duty Clause, requires employers to furnish a workplace free of recognized hazards likely to cause death or serious physical harm where a feasible means of abatement exists.

Total Recordable Incident Rate = (number of OSHA recordable cases x 200,000) / total employee hours worked; the constant 200,000 represents 100 employees working 40 hours for 50 weeks.

DART rate uses the same 200,000 multiplier but counts only cases involving days away from work, restricted work activity, or job transfer.

29 CFR 1904.39 requires reporting a work-related fatality to OSHA within 8 hours and an inpatient hospitalization, amputation, or loss of an eye within 24 hours.

Hierarchy of controls ranked from most to least effective: elimination, substitution, engineering controls, administrative controls, then personal protective equipment.

Leading indicators (inspections completed, near-miss reports, training hours) predict future performance; lagging indicators (TRIR, DART, severity rate) describe outcomes already realized.

ANSI/ASSP Z10 and ISO 45001 both apply the Plan-Do-Check-Act cycle: policy, planning, implementation and operation, evaluation, and management review.

Written programs such as hazard communication, permit-required confined space, and lockout/tagout are triggered by the presence of the hazard, not by employer size.

Incident investigation should trace causal factors to management-system weaknesses (training, design, procurement, supervision) rather than stopping at worker error.

Exposure limits come from three sources: OSHA PELs (29 CFR 1910 Subpart Z, Table Z-1), NIOSH RELs, and ACGIH TLVs; PELs are legally enforceable, RELs and TLVs are not.

A TLV-STEL is a 15-minute time-weighted average permitted no more than four times per workday, with at least 60 minutes between excursions.

Ceiling limits (TLV-C, PEL-C) must never be exceeded at any instant and take precedence over 8-hour averages for fast-acting substances.

Convert ppm to mg/m3 at 25 C and 1 atm: mg/m3 = (ppm x molecular weight) / 24.45; use 22.4 as the molar volume constant at 0 C.

Noise dose D = 100 x sum of (time exposed at a level / time allowed at that level); a dose of 100 percent equals the permissible exposure limit.

OSHA uses a 5 dBA exchange rate (90 dBA for 8 hours, 95 dBA for 4 hours); NIOSH uses 3 dBA, so NIOSH limits are more protective at high levels.

The OSHA action level of 85 dBA as an 8-hour TWA triggers a hearing conservation program: monitoring, audiometric testing, hearing protection, training, and recordkeeping.

Mixed exposures are evaluated with the additive formula: sum of (concentration / limit) for each agent; a sum greater than 1 indicates overexposure.

Oxygen deficiency is below 19.5 percent by volume and oxygen enrichment is above 23.5 percent; both conditions change fire and entry risk in confined spaces.

Excavations 5 feet or deeper require a protective system (sloping, benching, shoring, or shielding) unless a competent person determines there is no indication of collapse; at 4 feet a means of egress is required within 25 feet of lateral travel.

Spoil piles, equipment, and materials must be kept at least 2 feet back from the edge of an excavation to prevent surcharge loading and collapse.

Fall protection thresholds: 6 feet in construction (29 CFR 1926 Subpart M), 4 feet in general industry (1910.28), and 10 feet for scaffolds.

Portable ladders are set at a 4:1 slope, extend at least 3 feet above the landing surface, and are secured against displacement.

29 CFR 1910.147 requires the authorized employee to verify a zero energy state after applying locks and tags, typically by attempting startup or testing for residual energy.

A job hazard analysis follows four steps: select the job, break it into sequential steps, identify hazards in each step, and determine and document controls.

Risk score = likelihood x severity; scores are plotted on a risk matrix to rank hazards and set control priority.

HAZOP applies guide words (no, more, less, reverse, part of, as well as, other than) to process parameters to find deviations from design intent.

A space is a permit-required confined space when it contains a hazardous atmosphere, engulfment potential, entrapment configuration, or any other recognized serious hazard.

The fire tetrahedron consists of fuel, oxygen, heat, and a self-sustaining chemical chain reaction; removing any one element extinguishes combustion.

Extinguisher classes: A ordinary combustibles, B flammable liquids and gases, C energized electrical equipment, D combustible metals, K commercial cooking oils.

No extinguisher with a C rating alone is listed; Class C protection requires a rating on an A or B extinguisher that is safe on energized electrical equipment.

OSHA 1910.157 travel distances: Class A extinguishers within 75 feet of employees, Class B within 30 to 50 feet depending on hazard level, Class D within 75 feet.

PASS technique: Pull the pin, Aim at the base of the fire, Squeeze the handle, Sweep side to side; portable extinguishers are for incipient-stage fires only.

29 CFR 1910.38 requires a written emergency action plan when 11 or more employees are present; smaller employers may communicate the plan orally.

Exit routes must be at least 28 inches wide at all points and kept unobstructed; NFPA 101 sets a 90-minute duration for emergency lighting.

NFPA 101 limits travel distance to the nearest exit to about 200 feet in unsprinklered spaces and 250 feet in sprinklered spaces for most occupancies.

Standard sprinkler heads in ordinary-hazard occupancies activate at about 165 F; the 1910.38 and 1910.157 elements must be covered in employee training.

RCRA hazardous waste characteristics are ignitability (flash point below 140 F), corrosivity (pH of 2 or less, or 12.5 or greater), reactivity, and toxicity (TCLP).

Generator categories: very small quantity generator below 100 kg/month, small quantity generator 100 to 1,000 kg/month, large quantity generator 1,000 kg/month or more.

Accumulation limits without a permit: 90 days for a large quantity generator, 180 days for a small quantity generator, and up to 270 days if the treatment facility is more than 200 miles away.

A CERCLA release of a hazardous substance at or above its reportable quantity must be reported immediately to the National Response Center.

EPCRA Section 312 Tier II inventory reports are due by March 1 each year; Section 313 Toxic Release Inventory Form R is due by July 1.

The waste management hierarchy is source reduction first, then reuse, recycling, treatment, and disposal as the last option.

An SPCC plan is required for oil storage capacity above 1,320 gallons aboveground or 42,000 gallons underground with a potential discharge to navigable waters.

The Clean Water Act requires an NPDES permit for point-source discharges and a stormwater pollution prevention plan for industrial stormwater discharges.

Universal wastes (batteries, lamps, mercury-containing equipment, and certain pesticides) may be managed under relaxed accumulation rules but remain banned from ordinary disposal.