What is industrial hygiene?
Industrial hygiene is based on a simple idea: many work-related illnesses are not caused by a single event, but by repeated exposure to something present in the air, on surfaces, or in the physical environment of the workplace. Silica dust, solvents, welding fumes , noise , vibrations, radiation, heat, and biological agents are all examples. This exposure is often invisible to the worker, and its effects appear years later. Therefore, a discipline is needed to anticipate, measure, and control it.
In Spain, industrial hygiene is one of the four preventive specialties recognized by the Regulations for Prevention Services, along with occupational safety, ergonomics and applied psychosocial factors, and occupational medicine. Prevention services must have specialists in this field, and higher-level functions in industrial hygiene require the training regulated in Annex VI of Royal Decree 39/1997.
Occupational hygiene differs from workplace safety in the type of harm it prevents (illness and deterioration of health versus injury from accidents) and from occupational medicine in its focus (the environment and exposure versus the individual and its effects). The three are complementary: health surveillance detects effects that hygiene must explain and correct.
Agents studied by industrial hygiene
- Chemical agents. Substances and mixtures in the form of gas, vapor, aerosol, dust, fiber, or liquid that can be absorbed by inhalation, skin contact, or ingestion. Regulated by Royal Decree 374/2001 and, for carcinogens, mutagens, and reprotoxicants, by Royal Decree 665/1997.
- Physical agents. Noise (Royal Decree 286/2006), mechanical vibrations (Royal Decree 1311/2005), ionizing and non-ionizing radiation, electromagnetic fields, artificial optical radiation, thermal environment and lighting.
- Biological agents. Microorganisms, cell cultures and endoparasites capable of causing infection, allergy or toxicity, regulated by Royal Decree 664/1997.
Each family has its own regulations, reference values, and measurement methods, but shares the same action plan: identify, evaluate, control, and verify.
How is exposure assessed?
- Identification: inventory of agents present based on safety data sheets, processes, materials and working conditions.
- Initial assessment: qualitative estimation of exposure to decide where measurement is necessary and where exposure is clearly negligible or clearly unacceptable.
- Measurement: personal or environmental sampling using standardized methods, under representative conditions, and laboratory analysis where appropriate; comparison with occupational exposure limit values , in Spain those published annually by the INSST for chemical agents and the values set by each regulation for physical agents.
- Assessment: conclusion on whether the exposure is acceptable, uncertain or unacceptable, taking into account the variability and uncertainty of the measurement and the existence of particularly sensitive people.
- Control: measures ordered according to the hierarchy of controls, agent substitution, source control, ventilation and extraction, work organization and, ultimately, individual protection.
- Periodic verification: repetition of measurements according to the deadlines of the applicable regulation and whenever conditions change.
Limit values are not boundaries between safe and dangerous, but references for management: exposure must be reduced to the lowest technically possible level and, in the case of carcinogens, the limit value does not exempt from the obligation of substitution and minimization.
Organizational application
Industrial hygiene is integrated into the preventive management system through:
- Prevention service. It provides the expertise, plans the measurements and prepares the evaluation reports; external services must have it and the appropriate measurement equipment.
- Purchasing and engineering. Product substitution and the design of facilities with source control are the most effective measures and depend on these areas.
- Controls and maintenance. They ensure that extraction systems, enclosures and equipment are maintained and function as designed.
- Health surveillance. Agent-specific protocols allow for the early detection of effects and provide feedback for hygiene assessment.
- Workers and their representatives. Information on the agents and their risks, training in the use of controls, and consultation on measurements and their results.
Exposure records have long-term value: for carcinogens and biological agents, regulations require maintaining records and lists of exposed individuals for decades. Digital systems allow this history to be maintained by person and by job position and linked to health surveillance.
Limits and common mistakes
- Measuring without prior identification: measurements without an inventory of agents or exposure hypotheses produce data without conclusions.
- Taking a single point measurement as representative of the usual exposure, ignoring the variability between days, tasks and people.
- Considering exposure acceptable only because it is below the limit value, without applying the principle of reducing to the lowest possible level.
- Relying on respiratory protection as the primary measure instead of substituting or controlling at the source.
- Forgetting the dermal route and ingestion in the evaluation of chemical agents.
- Do not repeat measurements after changes in process, products, or work pace.
Industrial hygiene alone does not cover the safety risks of the same agents (fire, explosion, dangerous reactions), which are assessed with other techniques, nor the ergonomic and psychosocial risks of the job.
Practical example
Situation: An industrial carpentry workshop with thirty people detects several cases of rhinitis in health surveillance and suspects exposure to wood dust.
- Identification. Inventory of woods used, including hardwoods classified as carcinogenic, and of dust-generating operations: cutting, sanding, cleaning with compressed air.
- Measurement. Personal sampling of inhalable fraction at three stations during two days, using a standardized method and analysis in an accredited laboratory.
- Results. Unacceptable exposure during manual sanding and cleaning with compressed air; acceptable with extraction in cutting machines.
- Measures. Prohibition of blowing and replacement with vacuuming, sanders with integrated extraction, review of the extraction system, respiratory protection during the transition, training and information, and updating of the list of people exposed to carcinogens.
- Verification. New measurement at six months and follow-up in health surveillance with the specific protocol.
Regulatory framework in Spain
- Royal Decree 39/1997, articles 34 to 37 and annex VI . Industrial hygiene as a preventive specialty and higher level training.
- Royal Decree 374/2001 . Protection against risks related to chemical agents during work; assessment, limit values and measures.
- Royal Decree 665/1997 . Protection against carcinogenic, mutagenic and reprotoxic agents during work.
- Royal Decree 286/2006 . Protection against the risks arising from exposure to noise.
- Royal Decree 664/1997 . Protection against risks related to exposure to biological agents.
- Occupational exposure limits for chemical agents in Spain (INSST, annual edition) . Environmental and biological reference limit values adopted in Spain.
Spanish legislation transposes European directives on chemical agents (98/24/EC), carcinogens (2004/37/EC, as amended), noise (2003/10/EC), vibrations (2002/44/EC), and biological agents (2000/54/EC). In other countries, this discipline is called occupational hygiene, and its limit values are derived from organizations such as the ACGIH, which has no legal force in Spain.
