Study guide
18.7 Abrasive Blasting and Surface Preparation
CIH Certified Industrial Hygienist Exam
Track your progress as you read
Finished sections get a check mark.
1 Chapter 1: The CIH Exam and How to Use This Guide
1.1 CIH Exam Format, Scoring, and Test-Day Logistics 1.2 Eligibility, Application Windows, Fees, and Certification Maintenance 1.3 The BGC Blueprint, Subject Areas, and a Calculation-First Study Plan
2 Chapter 2: Basic Science & Calculations
2.1 Gas Laws and Vapor Calculations 2.2 Unit Conversions: ppm, mg/m³, and Standard Temperature/Pressure 2.3 Fluid Mechanics and Airflow Fundamentals
3 Chapter 3: Air Sampling & Instrumentation
3.1 Active and Passive Air Sampling Strategies 3.2 Particulate and Aerosol Sampling 3.3 Direct-Reading Instruments and Calibration
4 Chapter 4: Analytical Chemistry & Lab Methods
4.1 Gas Chromatography and Mass Spectrometry 4.2 High-Performance Liquid Chromatography and Ion Chromatography 4.3 Spectroscopy and Elemental Analysis 4.4 Gravimetric, Microscopy, and Wet Chemical Methods 4.5 Laboratory Quality Assurance, Chain of Custody, and Desorption Efficiency
5 Chapter 5: Biostatistics & Epidemiology
5.1 Lognormal Distributions and Exposure Data Statistics 5.2 Upper Confidence Limits (UCL95) and Compliance Decision Rules 5.3 Epidemiological Study Designs and Measures of Association 5.4 Sampling Strategy: Sample Size, Power, and Worker Selection
6 Chapter 6: Toxicology & Biological Monitoring
6.1 Dose-Response Relationships and Points of Departure 6.2 Toxicokinetics: Absorption, Distribution, Metabolism, and Elimination 6.3 Aerosol Deposition, Clearance, and Respiratory Tract Dosimetry 6.4 Hepatic, Renal, Neurologic, and Hematologic Target Organ Toxicity 6.5 Pulmonary Toxicology, Carcinogenicity, and Reproductive Hazards 6.6 OEL Frameworks, Classifications, and Excursion Limits 6.7 Chemical Mixtures and Extended Work-Shift OEL Adjustments 6.8 Biological Exposure Indices (BEIs) and Biomonitoring
7 Chapter 7: Biohazards & Indoor Environmental Quality
7.1 Mold, Fungi, and Microbial Contaminants 7.2 Infectious Agents, Bloodborne Pathogens, and Biosafety Levels 7.3 Indoor Environmental Quality (IEQ) Investigations 7.4 Sanitation, Potable Water, and Personal Hygiene Programs
8 Chapter 8: Community Exposure & Environmental Health
8.1 Clean Air Act Framework, NAAQS, and New Source Review 8.2 Hazardous Air Pollutants, CEMS, and EPA Reference Methods 8.3 Atmospheric Stability, Lapse Rates, and Plume Morphology 8.4 Gaussian Plume Modeling, Plume Rise, and Environmental Fate 8.5 HAZWOPER Scope, Mandates, and Training Tiers 8.6 Protection Levels, Site Zoning, Incident Command, and Decontamination 8.7 Water Pollution, Hazardous Waste, and Community Right-to-Know
9 Chapter 9: Health Risk Analysis & Hazard Communication
9.1 GHS Hazard Classification: Health and Physical Hazard Criteria 9.2 GHS Labels, Safety Data Sheets, and Trade Secret Rules 9.3 The AIHA Exposure Assessment Strategy and Similar Exposure Groups 9.4 Qualitative Exposure Profiling and the AIHA Risk Matrix 9.5 Quantitative Health Risk Characterization: HQ, HI, and ELCR 9.6 NIOSH Occupational Exposure Banding 9.7 Risk Communication and Reporting to Affected Parties
10 Chapter 10: Industrial Ventilation Principles & LEV Design
10.1 Elimination, Substitution, Isolation, Containment, and Process Change 10.2 LEV Hood Taxonomy and Capture Velocity Selection 10.3 Hood Airflow Equations, Entry Losses, and Hood Static Pressure 10.4 Particulate Transport Aerodynamics and Duct Sizing 10.5 Duct Friction, Fitting Losses, and System Balancing 10.6 Fan Categories and Pressure Dynamics Across the Fan 10.7 System Curves, the Fan Laws, and Density Corrections
11 Chapter 11: General Ventilation, Air Cleaning & Diagnostics
11.1 Dilution Ventilation Principles and Steady-State Modeling 11.2 Transient Purging and Air Distribution Geometry 11.3 Particulate Air Cleaning: Cyclones, Baghouses, Scrubbers, and ESPs 11.4 Gaseous Emission Control and Air Cleaner Selection 11.5 Ventilation System Troubleshooting and Testing
12 Chapter 12: Noise Measurement & Hearing Conservation
12.1 Acoustic Physics and Decibel Mathematics 12.2 Sound Propagation, Octave Bands, and Frequency Weighting 12.3 Noise Dose Metrics and OSHA versus ACGIH Criteria 12.4 Exchange Rates, Extended Shifts, and Dosimetry Field Protocols 12.5 Engineering Noise Controls and Hearing Protector Attenuation 12.6 Hearing Conservation Programs and Standard Threshold Shifts 12.7 Hand-Arm and Whole-Body Vibration
13 Chapter 13: Thermal Stress Assessment & Control
13.1 Wet Bulb Globe Temperature (WBGT) and Heat Stress Indices 13.2 Heat-Related Disorders, Acclimatization, and Work/Rest Regimens 13.3 Cold Stress Evaluation and Wind Chill
14 Chapter 14: Ionizing Radiation Protection
14.1 Ionizing Radiation Physics and Radioactive Decay Kinetics 14.2 Radiation Units, Radiobiology, and Health Effects 14.3 ALARA, Stay-Time, and the Inverse Square Law 14.4 Shielding Physics, Material Selection, and Gamma Constants 14.5 Radiation Detection Instruments and Spectrometry 14.6 Personnel Dosimetry, Dose Limits, and Contamination Surveys
15 Chapter 15: Non-Ionizing Radiation & Laser Safety
15.1 The Non-Ionizing Spectrum and Static/ELF Field Exposures 15.2 Radiofrequency and Microwave Exposure: SAR, Standards, and Surveys 15.3 Ultraviolet, Visible, and Infrared Radiation Hazards 15.4 Laser Safety Classifications and Optical Density Calculations 15.5 Illumination, Lighting Design, and Visual Performance
16 Chapter 16: Non-Engineering Controls & Personal Protective Equipment
16.1 Respiratory Protection Programs and Assigned Protection Factors 16.2 Maximum Use Concentration, Oxygen Deficiency, and Breathing Air 16.3 Particulate Filters, Sorbent Cartridges, and Change Schedules 16.4 Respirator Fit Testing Protocols 16.5 Chemical Protective Clothing and Dermal Exposure Control
17 Chapter 17: Ergonomics & Workstation Design
17.1 Soft-Tissue Biomechanics and WMSD Pathophysiology 17.2 Ergonomic Risk Factors and Their Interaction Effects 17.3 The Revised NIOSH Lifting Equation 17.4 RULA, REBA, the Strain Index, and the ACGIH HAL TLV 17.5 Anthropometry and Workstation Geometry 17.6 VDT Workstations, Hand Tool Design, and Administrative Ergonomics
18 Chapter 18: Work Environments & Industrial Processes
18.1 Welding Fume Emissions, Metal Fume Fever, and Cr(VI)/Manganese Toxicology 18.2 Foundry Operations and Hot Work Fire Prevention 18.3 Vapor Degreasing, Pickling, Electroplating, and Cyanide Baths 18.4 Spray Coatings, Isocyanates, and Semiconductor Manufacturing 18.5 Confined Spaces and High-Hazard Industrial Operations 18.6 Asbestos, Lead, and Silica: Regulated Substance Programs 18.7 Abrasive Blasting and Surface Preparation
19 Chapter 19: IH Program Management & Professional Ethics
19.1 The BGC Code of Ethics: Canons and Enforcement 19.2 Professional Liability, Standard of Care, and Expert Testimony 19.3 Occupational Health & Safety Management Systems (ISO 45001, ANSI Z10) 19.4 Exposure Records Access and Medical Surveillance 19.5 OSHA Injury and Illness Recordkeeping and Enforcement
18.7 Abrasive Blasting and Surface Preparation
Key Takeaways Explain This Topic AI
Silica sand as an abrasive is the classic preventable exposure; NIOSH recommends substitution with lower-silica media such as steel grit, garnet, or staurolite.
The substrate matters as much as the abrasive: blasting painted steel can release lead, cadmium, or chromium regardless of how clean the medium is.
OSHA 29 CFR 1910.94(a) requires blast-cleaning enclosures to be exhaust ventilated so that a continuous inward flow of air is maintained at all openings.
Abrasive-blasting operators must use a NIOSH-approved type CE supplied-air respirator with a hood or helmet, not an air-purifying respirator.
Blasting generates noise routinely exceeding 105 dBA, heat stress inside the hood, and injection injuries from the abrasive stream, so the hazard assessment must be multi-agent.
Last updated: August 2026
Abrasive Blasting and Surface Preparation
Abrasive blasting appears in the BGC Work Environments and Industrial Processes subject area alongside welding, spray painting, and vapour degreasing. It is worth studying carefully because it is a multi-agent operation: a single task simultaneously produces respirable silica, toxic metals, extreme noise, heat stress, and a physical injection hazard, and each requires a different control.
1. Two Independent Sources of Exposure
The most common analytical error in blasting assessment is attributing all exposure to the abrasive. ABRASIVE MEDIUM SUBSTRATE COATING
- (what you shoot) (what you shoot at)
- | |
- Silica, metals, Lead, cadmium,
- trace contaminants chromium, zinc,
- | coal tar, PCBs
- | |
- +------------> AIRBORNE <------------+
- DUST
Blasting a lead-painted bridge with a silica-free abrasive still produces a lead exposure , frequently far above the PEL, and the resulting spent media is likely a toxicity-characteristic hazardous waste. The exposure assessment must always cover both the medium and the coating.
2. Abrasive Media
Medium Silica content Notes
Silica sand Very high The classic cause of accelerated silicosis in blasters; banned or heavily restricted in many jurisdictions and strongly discouraged by NIOSH
Coal slag / boiler slag Low crystalline silica Widely used, but can contain beryllium, arsenic, and other trace metals; requires its own hazard evaluation
- Garnet Low Good performance, low free silica
- Staurolite Low Low free silica alternative
- Steel shot and grit None Recyclable, low dust generation, but heavy and requires recovery equipment
Aluminium oxide, silicon carbide None (silicon carbide is not crystalline silica) Aggressive cutting, higher cost
Sodium bicarbonate, dry ice, plastic media None Low-aggression options for sensitive substrates; dry ice adds a CO₂ asphyxiation hazard in confined areas
NIOSH's long-standing recommendation is substitution away from silica sand , which is the highest-order control available for the medium. Note the exam trap: silicon carbide is not crystalline silica , and a low-silica medium does not address the coating hazard at all.
Wet and vacuum blasting methods suppress dust at the point of generation and are a process-change control that reduces both worker exposure and site contamination.
3. Enclosure and Ventilation Requirements
OSHA 29 CFR 1910.94(a) governs abrasive blasting ventilation, and the core requirement is directional:
The blast-cleaning enclosure shall be exhaust ventilated in such a way that a continuous inward flow of air will be maintained at all openings of the enclosure during the blasting operation.
Associated requirements:
Doors must be flanged and tight when closed; doors on the ends of blast enclosures containing conveyors must overlap the opening.
Exhaust ducts must not discharge into the workroom ; the dust collector must be located outside the blasting enclosure area where practicable.
Visibility inside the enclosure must be maintained by adequate ventilation, since a blaster who cannot see is both less productive and less safe.
Blast cleaning rooms that operators enter require sufficient air changes and a supply of make-up air.
Static electricity must be controlled by bonding and grounding, since dry abrasive flowing through a hose generates substantial charge.
The pressure logic is the mirror image of the operator booth discussed under isolation and containment: the blast enclosure is negative relative to the room, while any operator enclosure is positive relative to the room.
4. Respiratory Protection: Type CE Is Mandatory
This is the most frequently tested single fact about abrasive blasting.
Operators performing abrasive blasting must wear a NIOSH-approved type CE abrasive-blasting respirator — a supplied-air respirator with a hood or helmet that also protects the head and neck from rebounding abrasive. Type CE respirators are approved in continuous-flow and pressure-demand configurations.
An air-purifying respirator is not acceptable for the blasting operator , for several converging reasons:
Dust concentrations inside a blast hood routinely reach hundreds of times the exposure limit, exceeding any air-purifying respirator's maximum use concentration.
The blast stream carries no warning properties and no reliable end-of-service indicator.
A hood is required for impact protection from rebounding abrasive regardless of the respiratory question.
Breathing air must meet CGA Grade D or better : 19.5 to 23.5% oxygen, carbon monoxide no more than 10 ppm, carbon dioxide no more than 1,000 ppm, condensed hydrocarbons no more than 5 mg/m³, and no objectionable odour. Where an oil-lubricated compressor supplies the air, a carbon monoxide alarm or high-temperature alarm is required, because compressor overheating produces CO directly at the intake side of the system. Compressor intakes must be sited away from vehicle exhaust and other combustion sources.
Helpers and adjacent workers who are not inside the blast stream still require respiratory protection selected on the basis of their own measured exposure — commonly a half-mask or full facepiece with a P100 filter, but that determination must be made from data.
5. The Other Agents
Noise. Abrasive blasting is among the loudest routine industrial operations, commonly exceeding 105 dBA at the operator and often higher inside an enclosure where reverberation adds several decibels. Dual hearing protection is frequently necessary, and the blast hood itself provides little attenuation. A worker at 105 dBA reaches 100% OSHA dose in under an hour.
Heat stress. The hood, the protective suit, and the supplied air combine to impair evaporative cooling. Supplied air can be conditioned with a vortex tube or air-conditioning device, which is a genuine engineering heat-stress control rather than a comfort item. Work/rest scheduling and hydration must be planned before the job, not improvised.
Physical injury. The abrasive stream can cause severe injection injury and subcutaneous emphysema on contact with skin. Controls include a dead-man control valve on the nozzle that stops flow when released, nozzle-hose coupling restraints and whip checks to prevent hose whipping if a coupling fails, and prohibiting the practice of directing the nozzle at another person.
Confined space. Blasting inside tanks, vessels, and ship hulls combines all of the above with a permit-required confined space: the operation itself generates the atmospheric hazard, so continuous monitoring, forced ventilation, an attendant, and rescue provisions are required.
6. Waste and Environmental Considerations
Spent abrasive contains both the medium and everything removed from the substrate. Where the coating contained lead, cadmium, or chromium, the spent media frequently fails the Toxicity Characteristic Leaching Procedure and must be managed as hazardous waste. Outdoor blasting also requires containment — shrouding, negative-pressure enclosures, or ground sheeting — to prevent site and off-site contamination and to protect adjacent workers and the community.