CIH Study Guide 2026

When dual hearing protection is used, OSHA and NIOSH recommend adding approximately 5 dB to the higher NRR because bone conduction limits the combined attenuation achievable.

Noise, particularly at levels exceeding 85 dB, is categorized as a physical hazard in industrial hygiene. Physical hazards are environmental factors that can cause harm through physical mechanisms, distinct from chemical or biological interactions. Prolonged exposure to high noise levels can lead to permanent hearing loss, stress, and other adverse health effects, making it a critical concern for industrial hygienists.

Butyl rubber gloves provide superior resistance to ketones, esters, and many polar organic solvents, making them the preferred selection for these chemical classes.

States can develop and enforce their own occupational safety and health programs, known as State Plans, in lieu of federal OSHA enforcement. A fundamental requirement for OSHA approval of a State Plan is that the state's standards and enforcement must be "at least as effective" as federal OSHA's. This ensures workers receive comparable or better protection, even if the specific rules differ from the federal ones.

The TLV-TWA (Threshold Limit Value - Time-Weighted Average) is defined as the time-weighted average concentration for a normal 8-hour workday and a 40-hour workweek. This value represents the average exposure over this period that nearly all workers can be repeatedly exposed to without adverse health effects.

Administrative controls involve implementing policies, procedures, and work practices that reduce exposure to hazards, such as limiting time in hazardous areas, job rotation, or developing safe work procedures. These controls directly manage how workers interact with the hazard, effectively minimizing exposure duration or intensity. In many scenarios, especially when engineering controls are not fully feasible or sufficient, well-designed administrative controls can be the most practical and effective means to significantly reduce or remove occupational health risks.