Industrial hygiene (IH) is the science and art of anticipating, recognizing, evaluating, and controlling workplace environmental factors and stresses that may cause sickness, impaired health, or significant discomfort among workers. Chemical hazards represent one of the most prevalent and complex challenges in industrial hygiene practice.
The Hierarchy of Controls
The National Institute for Occupational Safety and Health (NIOSH) hierarchy of controls provides a framework for selecting chemical hazard control strategies, ranked from most to least effective: Elimination (physically removing the hazard), Substitution (replacing the hazard with a less dangerous chemical or process), Engineering Controls (isolating workers from the hazard through ventilation, enclosures, or process changes), Administrative Controls (changing how work is done through procedures, job rotation, and training), and Personal Protective Equipment (PPE) (providing protective gear such as respirators and gloves as the last line of defense).
Exposure Monitoring and Assessment
Quantitative exposure assessment is a cornerstone of industrial hygiene practice. Industrial hygienists use air sampling techniques — including area monitoring and personal breathing zone sampling — to measure worker exposures and compare them against established occupational exposure limits (OELs). OSHA Permissible Exposure Limits (PELs), ACGIH Threshold Limit Values (TLVs), and NIOSH Recommended Exposure Limits (RELs) serve as benchmarks for acceptable exposure levels.
Ventilation as a Key Control Strategy
Local exhaust ventilation (LEV) systems are among the most effective engineering controls for chemical exposures. LEV systems capture contaminants at their source before they can disperse into the work environment. Proper design, installation, maintenance, and regular testing of LEV systems are essential. General dilution ventilation, while less effective than LEV for hazardous chemicals, can be appropriate for low-toxicity substances when properly designed. Industrial hygienists also play a key role in conducting workplace chemical inventories, reviewing Safety Data Sheets, and developing chemical hygiene plans.
