Safety, Health, and Environment
Protecting people, plant, and environment, measured with the formulas OSHA and EPA actually use.
Hazard and control
The hierarchy of controls, from most to least effective: elimination, substitution, engineering controls, administrative controls, then personal protective equipment. PPE is the last line of defense, not the first. Hazard analysis tools: HAZOP applies guide words to process nodes; FMEA scores risk priority number = severity × occurrence × detection; fault trees reason deductively from a top event; job safety analysis breaks a task into steps and hazards. Lockout/tagout controls hazardous energy during maintenance, and confined-space entry requires atmospheric testing, ventilation, an attendant, and a permit.
Exposure measurement
OSHA noise: 90 dBA time-weighted average over 8 hours as the permissible exposure limit, 85 dBA action level for hearing conservation, and a 5 dB exchange rate - so 95 dBA is allowed for only 4 hours. Heat stress is assessed with WBGT plus acclimatization and work/rest cycles. Industrial hygiene limits include TLV-TWA, STEL, and ceiling; an 8-hour exposure is concentration × time ÷ 8 hours.
Metrics
Incidence rate = (recordable cases × 200,000) ÷ hours worked, where 200,000 = 100 workers × 40 hours × 50 weeks. DART counts days away, restricted, or transferred cases. First aid is generally not recordable; medical treatment beyond first aid is.
Environment
Clean Air Act, Clean Water Act, RCRA (cradle-to-grave hazardous waste; large quantity generator ≥ 1,000 kg/month), CERCLA, and EPCRA/SARA Title III reporting. Pollution prevention hierarchy: source reduction, recycling, treatment, disposal.
Traps
Calling PPE an engineering control; using a 3 dB instead of 5 dB exchange rate; using 100,000 instead of 200,000 in the incidence rate; treating a first-aid case as recordable.
Worked example
Seven recordable cases over 450,000 hours: (7 × 200,000)/450,000 = 3.11 cases per 100 full-time workers.