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18.6 Asbestos, Lead, and Silica: Regulated Substance Programs

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CIH Certified Industrial Hygienist Exam

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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

18.6 Asbestos, Lead, and Silica: Regulated Substance Programs

Key Takeaways Explain This Topic AI

The asbestos PEL is 0.1 fibre per cubic centimetre as an 8-hour TWA with an excursion limit of 1.0 f/cc over 30 minutes.

Construction asbestos work is divided into Classes I through IV by the material disturbed and the nature of the work, with Class I being the most stringent.

The lead PEL is 50 µg/m³ with an action level of 30 µg/m³; medical removal is required at a blood lead of 60 µg/100 g or an average of the last three tests at or above 50, with return below 40.

The respirable crystalline silica PEL is 50 µg/m³ with an action level of 25 µg/m³, and medical surveillance must be offered to employees exposed at or above the action level for 30 or more days per year.

The construction silica standard offers Table 1 specified exposure control methods as an alternative to exposure monitoring for named tasks.

Last updated: August 2026

Asbestos, Lead, and Silica: Regulated Substance Programs

Three substances account for a large share of the industrial hygienist's regulatory workload, and each is governed by a comprehensive, expanded standard with its own limits, triggers, and programme elements. The exam tests these numbers directly, and it tests the differences between them.

1. The Numbers at a Glance

  • Asbestos Lead Respirable crystalline silica
  • General industry standard 29 CFR 1910.1001 29 CFR 1910.1025 29 CFR 1910.1053
  • Construction standard 29 CFR 1926.1101 29 CFR 1926.62 29 CFR 1926.1153
  • PEL (8-h TWA) 0.1 f/cc 50 µg/m³ 50 µg/m³
  • Action level 0.1 f/cc (no separate AL; monitoring triggers apply) 30 µg/m³ 25 µg/m³
  • Excursion limit 1.0 f/cc over 30 minutes none none

Analytical method Phase contrast microscopy (PCM); TEM for clearance and speciation Flame AAS or ICP after acid digestion X-ray diffraction or FTIR on a respirable sample

2. Asbestos

Exposure limits. 0.1 f/cc as an 8-hour TWA and 1.0 f/cc averaged over 30 minutes as an excursion limit. Both must be met.

Counting rules. Phase contrast microscopy counts fibres longer than 5 µm with an aspect ratio of at least 3:1 . PCM cannot distinguish asbestos from other fibres, so a PCM count in a fibrous but non-asbestos environment overstates asbestos exposure; transmission electron microscopy provides speciation and counts thin fibres PCM cannot resolve.

Construction work classes. The construction standard assigns every job to a class, and the class drives the required controls:

Class Work Examples

I Removal of thermal system insulation and surfacing asbestos-containing material Pipe lagging, sprayed-on fireproofing

  • II Removal of other asbestos-containing material Floor tile, roofing, siding, transite
  • III Repair and maintenance operations that disturb ACM Cutting into a wall containing ACM to reach a valve
  • IV Custodial activities cleaning up dust and debris from Class I–III work Housekeeping in a regulated area

Class I is the most stringent, requiring critical barriers, negative-pressure enclosures, decontamination units, and supervision by a competent person.

Regulated areas are required wherever exposure exceeds or can reasonably be expected to exceed a limit, with demarcation, restricted access, warning signs, and no eating, drinking, smoking, or applying cosmetics.

Presumed asbestos-containing material (PACM). Thermal system insulation and surfacing material in buildings constructed before 1981 is presumed to contain asbestos unless a rebuttal is established by a qualified person.

Notification: results of monitoring within 15 working days of receipt.

Clearance. After abatement, air clearance is commonly performed by aggressive sampling with PCM at 0.01 f/cc, or by TEM where higher confidence or regulatory requirement demands it.

3. Lead

Exposure limits. PEL 50 µg/m³ as an 8-hour TWA; action level 30 µg/m³ , which triggers exposure monitoring, biological monitoring, and training.

Biological monitoring and medical removal are the defining features of the lead standard:

  • Trigger Requirement (general industry)
  • Exposure at or above the AL for more than 30 days per year Blood lead and ZPP at least every 6 months
  • Blood lead at or above 40 µg/100 g Testing at least every 2 months until two consecutive results are below 40

Blood lead at or above 60 µg/100 g , or an average of the last three tests at or above 50 µg/100 g Medical removal from lead exposure

  • Return to work Two consecutive blood lead results below 40 µg/100 g
  • Blood lead at or above 40 µg/100 g Individual written notification within 5 working days of receipt
  • Air monitoring results Notification within 15 working days of receipt

Medical removal protection benefits preserve earnings, seniority, and benefits for up to 18 months, which is what makes removal practicable rather than punitive.

A crucial currency caveat. The OSHA blood lead triggers date from 1978 and are far above modern health-based guidance. The ACGIH BEI for lead is 20 µg/100 g, and public health bodies recommend removal from exposure at levels well below the OSHA figures. An exam item may ask for the OSHA regulatory number; professional practice should be guided by the lower health-based values.

Hygiene facilities. Change rooms with separate storage for street and work clothing, showers where feasible, and lunchrooms with filtered positive-pressure air. Employer laundering; no removal of contaminated clothing from the workplace by employees; no compressed air or shaking to clean clothing.

4. Respirable Crystalline Silica

Exposure limits. PEL 50 µg/m³ as an 8-hour TWA; action level 25 µg/m³ .

Two compliance routes in construction. The construction standard offers a choice:

Table 1 — specified exposure control methods. For eighteen named tasks (stationary masonry saws, handheld power saws, drilling rigs, jackhammers, walk-behind saws, rig-mounted core saws, dowel drilling, vehicle-mounted drilling, and others) the standard specifies engineering controls — typically integrated water delivery or a shroud with dust collection — plus work practices and, for some tasks and durations, respiratory protection. A fully compliant Table 1 employer need not perform exposure monitoring at all.

The alternative exposure control method. Assess exposure by monitoring or objective data and control to the PEL.

Table 1 is the reason the construction silica standard changed field practice so quickly: it converts an assessment problem into an equipment specification.

Programme elements. A written exposure control plan identifying the tasks, the controls, the housekeeping practices, and the procedures to restrict access; a competent person in construction to implement and inspect it; and housekeeping restrictions that prohibit dry sweeping and compressed-air cleaning where a safer alternative is available.

Medical surveillance must be offered to employees exposed at or above the action level for 30 or more days per year in general industry, and includes a chest X-ray read by a NIOSH B-reader, spirometry, and a tuberculosis test, repeated at least every three years.

Notification: within 15 working days after completing an exposure assessment.

Analysis. Respirable samples are collected with a cyclone at the 4 µm 50% cut point and analysed for crystalline silica content by X-ray diffraction or infrared spectroscopy — a bulk gravimetric result alone does not measure silica.

5. What the Three Standards Have in Common

Every expanded health standard follows the same architecture, and recognising it lets you reason about a standard you have not memorised: Exposure assessment -> Regulated area / access control

  • | |
  • v v
  • Engineering & work-practice controls first, respirators after
  • |
  • v
  • Medical surveillance -> Removal / referral where triggered
  • |
  • v
  • Hygiene facilities -> Training -> Recordkeeping (30 yr / duration + 30 yr)
  • |
  • v
  • Written programme, competent person, and employee notification

The differences that matter for the exam are the numbers and the substance-specific twists : asbestos has an excursion limit and work classes, lead has biological monitoring and medical removal protection, and silica has Table 1 and a B-reader chest X-ray.