NIOSH SHO Hazard Control cheat sheet

Anticipation means predicting hazards before a process, chemical, or task exists; identification means recognizing hazards in an existing operation; both precede control selection.

Exposure pathway model: hazard source → release/emission → transport through air, water, or surface → entry route (inhalation, dermal, ingestion, injection) → exposed worker.

Walk-through survey outputs: task inventory, agent inventory (chemicals, physical agents, biologicals), exposed worker groups, and duration/frequency of exposure per task.

Similar Exposure Groups (SEGs) group workers with comparable tasks, agents, and controls; exposure monitoring and controls are then managed at the SEG level rather than per individual.

Material Safety Data Sheet (now Safety Data Sheet) review yields: CAS number, physical state, vapor pressure, boiling point, flash point, PELs, and known target organ effects.

Vapor pressure and boiling point predict airborne concentration potential: higher vapor pressure at a given temperature means greater potential for inhalation exposure.

Physical hazard categories to screen: noise, vibration, heat/cold stress, ionizing and non-ionizing radiation, illumination, ergonomic stressors, and pressure extremes.

Sampling strategy options: full-period consecutive sampling, partial-period sampling, grab sampling, and worst-case or peak sampling; selection depends on whether the agent has a ceiling limit or short-term limit.

NIOSH hierarchy, most to least effective: elimination, substitution, engineering controls, administrative controls, then personal protective equipment (PPE).

Elimination removes the hazard entirely (e.g., discontinue a process); substitution replaces it with a less hazardous agent, material, or process.

Engineering controls act on the hazard or the pathway at the source or along the transmission path and do not depend on worker behavior for effectiveness.

Administrative controls change how work is done (procedures, scheduling, training, rotation); they depend on worker compliance and supervision.

PPE is the last line of defense because it places the barrier on the worker and fails when fit, maintenance, or use is poor.

Control selection inputs: agent toxicity and physical properties, exposure magnitude versus the occupational exposure limit, number of exposed workers, task duration, and feasibility.

Interim controls may be used while engineering controls are designed or installed, but the plan must state a timeline and a verification endpoint.

Controls should be selected to protect the most sensitive exposed group, including workers with pre-existing conditions, pregnant workers, and contractors on site.

Local exhaust ventilation (LEV) captures contaminant at or near the source; components are hood, duct, air cleaner, fan, and exhaust stack.

Capture velocity is the air speed needed at the source to capture the contaminant; it is distinct from transport (duct) velocity, which keeps material moving in the duct.

Duct transport velocity must exceed the settling velocity of the particulate; too low causes buildup, too high causes abrasion, noise, and energy waste.

Hood design rules: enclose the source where possible, keep the hood close to the source, and avoid placing the worker between the source and the hood.

Push-pull ventilation uses a supply jet to push contaminant toward an exhaust hood; it is used for open-surface tanks and large welding or plating operations.

General dilution ventilation lowers concentration by mixing with clean air; it is unsuitable for highly toxic agents, and it cannot handle high emission rates or confined spaces.

Dilution ventilation airflow is estimated from the generation rate divided by the acceptable concentration difference between room air and supply air, adjusted by a mixing factor.

Static pressure is the pressure exerted against duct walls; velocity pressure is the pressure due to air movement, and total pressure is the sum of the two.

Balance and commissioning of a new LEV system should confirm hood face velocities and duct velocities against design specifications before the system is accepted.

Written programs required by OSHA standards include hazard communication, respiratory protection, hearing conservation, and permit-required confined space entry.

Training must be delivered in a language and at a literacy level the workers understand, and it must cover the specific hazards and controls at that site.

Job rotation reduces individual cumulative exposure but does not reduce total exposure and can spread exposure across more workers; use it only when engineering controls are not feasible.

Work-rest schedules for heat stress balance metabolic heat production against evaporative cooling; acclimatization and fluid replacement are part of the schedule design.

Housekeeping and hygiene practices: no eating, drinking, or smoking in contaminated areas, and handwashing before breaks and at the end of the shift.

Preventive maintenance schedules for ventilation, alarms, and monitoring instruments are administrative controls and must be documented.

Contractor and visitor coordination: the host employer must communicate site hazards and controls, and the contractor must inform the host of hazards brought on site.

Lockout/tagout and confined space entry permits are administrative controls that depend on strict adherence; they are not substitutes for engineering isolation.

Respirators: atmosphere-supplying respirators (SCBA, airline) are used for oxygen-deficient or IDLH atmospheres; air-purifying respirators require adequate oxygen and a known contaminant with an available cartridge.

Assigned Protection Factor (APF) is the workplace level of respiratory protection expected for a properly fitted and used respirator class; required APF = airborne concentration ÷ occupational exposure limit.

Maximum use concentration for a respirator class equals the APF multiplied by the exposure limit, and it must not exceed the cartridge or canister service limit.

Respirator fit testing: qualitative methods (saccharin, Bitrex, irritant smoke) rely on the wearer's response; quantitative methods (portacount, controlled negative pressure) measure leakage numerically.

Fit testing is required before initial use and annually thereafter; a user seal check is performed each time the respirator is donned.

Chemical protective clothing selection considers permeation (molecular breakthrough), degradation (material breakdown), and penetration (flow through closures and seams).

Glove selection: consult manufacturer permeation and degradation data for the specific chemical, concentration, and temperature; no single glove material resists all chemicals.

Hearing protection: Noise Reduction Rating (NRR) is a laboratory value; derate it (commonly by 50 percent for earmuffs and 70 percent for formable plugs) when estimating workplace protection.

Eye and face protection must be selected for the hazard type: impact, heat, chemical splash, dust, or optical radiation, and must meet ANSI Z87.1.

Verification confirms that a control was installed and functions as designed; validation confirms it actually reduces exposure to the intended level.

Exposure monitoring results are compared with the occupational exposure limit to calculate the hazard quotient or exposure ratio; a ratio above 1 indicates overexposure.

Full-shift personal sampling is the reference method for comparing results with 8-hour time-weighted average limits; short-term and ceiling limits require different sampling durations.

Statistical evaluation of exposure data should account for the geometric distribution of exposures; the geometric mean and geometric standard deviation describe typical exposure profiles.

Control banding tools (e.g., based on hazard band and exposure potential) can prioritize controls when quantitative exposure data are limited.

Medical surveillance is triggered by exposure above an action level, specific agent standards, or symptoms; results feed back into the hazard assessment cycle.

Program evaluation metrics include control downtime, respirator fit-test pass rates, training completion, and the trend of exposure monitoring results over time.

Reassessment triggers: process change, new chemical introduction, new equipment, reported symptoms, near misses, or a change in the exposure limit.