What is Industrial Hygiene?
Industrial hygiene is the science of anticipating, recognizing, evaluating, and controlling workplace conditions that may cause workers' injury or illness. It's a cornerstone of occupational health protection.
The Industrial Hygiene Framework
Anticipation: Identifying potential hazards before they cause harm
Recognition: Identifying existing hazards in the workplace
Evaluation: Measuring exposure levels and assessing risk
Control: Implementing measures to eliminate or reduce hazards
Types of Workplace Health Hazards
Chemical Hazards
Forms of chemical exposure:
Dusts (solid particles)Fumes (metal vapors that condense)Mists (liquid droplets)Gases (formless substances)Vapors (gaseous form of liquids)Routes of exposure:
Inhalation (most common)Skin absorptionIngestionInjectionPhysical Hazards
NoiseVibration (hand-arm and whole-body)Temperature extremes (heat and cold)Radiation (ionizing and non-ionizing)Pressure extremesBiological Hazards
BacteriaVirusesFungiParasitesBloodborne pathogensErgonomic Hazards
Repetitive motionsForceful exertionsAwkward posturesContact stressExposure Limits
Occupational Exposure Limits (OELs):
OSHA Permissible Exposure Limits (PELs):
Legal limits enforceable by OSHAMany are outdated (based on 1968 ACGIH TLVs)Apply to 8-hour time-weighted average (TWA)NIOSH Recommended Exposure Limits (RELs):
Science-based recommendationsMore protective than many PELsNot legally enforceableACGIH Threshold Limit Values (TLVs):
Updated annually based on current scienceWidely recognized best practicesNot legally enforceable but often usedTypes of limits:
TWA (Time-Weighted Average):: 8-hour average concentrationSTEL (Short-Term Exposure Limit):: 15-minute averageCeiling:: Never-to-exceed limitAction Level:: Trigger for medical surveillance (typically 50% of PEL)Exposure Monitoring Methods
Air Sampling
Personal sampling:
Sample collected in worker's breathing zoneRepresents actual worker exposureRequired for most OSHA compliance determinationsArea sampling:
Sample collected at fixed locationUseful for identifying sourcesNot representative of personal exposureSampling methods:
Integrated sampling:
Collects sample over extended periodProvides TWA concentrationUses pumps, tubes, filters, badgesDirect-reading instruments:
Provide real-time measurementsUseful for peak exposures and source identificationSome lack specificity (may respond to multiple substances)Biological Monitoring
Measures:
Parent compound in body (blood, urine)MetabolitesBiochemical effectsAdvantages:
Accounts for all routes of exposureReflects individual differences in absorptionValidates effectiveness of controlsExamples:
Blood lead for lead exposureUrine cadmium for cadmium exposureCarboxyhemoglobin for carbon monoxideNoise Monitoring
Noise exposure requirements:
Action level: 85 dBA TWA
Requires hearing conservation programAnnual audiometric testingHearing protection availabilityPEL: 90 dBA TWA
Engineering or administrative controls requiredHearing protection mandatoryFeasibility considerations applyMonitoring methods:
Noise dosimeters (personal exposure)Sound level meters (area noise levels)Octave band analyzers (frequency analysis for control selection)Conducting Exposure Assessments
Step 1: Characterize the Workplace
Gather information on:
Processes and operationsChemicals used and generatedPhysical agents presentNumber of workers exposedWork practices and patternsExisting controlsStep 2: Create Similar Exposure Groups (SEGs)
Group workers with similar exposure profiles:
Same job tasksSame work environmentSame exposure duration and frequencySame control measuresStep 3: Determine Monitoring Strategy
Options:
Qualitative assessment (judgment-based)Quantitative assessment (measurement-based)Combination approachConsider:
Severity of potential health effectsLikelihood of overexposureRegulatory requirementsAvailable exposure dataStep 4: Conduct Monitoring
Sampling considerations:
Representative of typical exposureCapture worst-case conditionsSufficient samples for statistical validityProper quality assuranceStep 5: Interpret Results
Compare to:
Applicable OEL (PEL, REL, TLV)Action levelsPrevious monitoring resultsStatistical analysis:
Account for sampling and analytical variabilityDetermine confidence in conclusionsConsider upper confidence limit of meanStep 6: Communicate Results
Inform:
Workers of their exposuresManagement of needed controlsMedical providers for surveillanceDocument:
Methods usedResults and interpretationRecommendationsControlling Exposures
Apply hierarchy of controls:
Elimination/Substitution:
Remove the hazard entirelyUse less hazardous materialsEngineering Controls:
Local exhaust ventilationEnclosure of processIsolation of workersWet methods for dustAdministrative Controls:
Work practice changesJob rotationSchedulingTrainingPersonal Protective Equipment:
Last resort when other controls inadequateRequires proper selection, fit, trainingOngoing program managementOSHA Substance-Specific Standards
Some substances have detailed requirements:
Lead (29 CFR 1910.1025)Asbestos (29 CFR 1910.1001)Benzene (29 CFR 1910.1028)Silica (29 CFR 1910.1053)Hexavalent chromium (29 CFR 1910.1026)Typical requirements:
Exposure monitoringMedical surveillanceWritten exposure control planTrainingRecordkeepingBuilding an Industrial Hygiene Program
Key elements:
Qualified personnel (CIH or supervised)Hazard recognition processExposure assessment strategyControl implementationMedical surveillance integrationRecordkeeping systemProgram evaluationCritical Dynamics provides comprehensive industrial hygiene services including exposure assessments, program development, and regulatory compliance support. Contact us to protect your workers from health hazards.