Slide 001: Respiratory Hazards in Abrasive Blasting¶
Slide Visual¶
Slide Overview¶
This slide identifies the specific respiratory hazards generated by abrasive blasting, explains how particle size determines health risk, and introduces occupational exposure limits relevant to makerspace operations.
Instruction Notes¶
Particle Size and Health Impact¶
Not all dust is equally dangerous. Particle size determines where inhaled material deposits in the respiratory system:
- Inhalable fraction (>10 μm): Trapped in nose and throat. Causes irritation but limited deep lung penetration.
- Thoracic fraction (4–10 μm): Penetrates to bronchi and large airways. Causes bronchitis, airway irritation.
- Respirable fraction (<4 μm): Reaches the gas-exchange region (alveoli). This is the dangerous fraction — causes silicosis, pneumoconiosis, and lung cancer depending on composition.
Abrasive blasting generates all three fractions. As media impacts the surface, both media fragments and substrate particles are aerosolized. Particles shatter progressively smaller with reuse.
Key Respiratory Diseases¶
Silicosis — caused by respirable crystalline silica (quartz). Irreversible fibrosis of lung tissue. Three forms: - Chronic: 10–30 years of moderate exposure - Accelerated: 5–10 years of heavy exposure - Acute: weeks to months of extreme exposure (fatal)
This is why silica sand blasting is banned or heavily restricted. Alternative media (aluminum oxide, garnet, glass bead) do not contain crystalline silica.
Mixed-Dust Pneumoconiosis — caused by inhaling combinations of mineral dusts. Even "safe" alternative media generate respirable dust that causes lung irritation over time.
Metal Fume Fever — caused by inhaling zinc, copper, or magnesium fumes from blasting galvanized or plated metals. Flu-like symptoms 4–8 hours after exposure.
Occupational Exposure Limits¶
| Substance | OSHA PEL (8-hr TWA) | ACGIH TLV | NIOSH REL |
|---|---|---|---|
| Crystalline silica | 50 μg/m³ | 25 μg/m³ | 50 μg/m³ |
| Aluminum oxide (total) | 15 mg/m³ | 1 mg/m³ (respirable) | 10 mg/m³ |
| Particulates NOS (total) | 15 mg/m³ | 3 mg/m³ (respirable) | — |
| Garnet (total) | 15 mg/m³ | 3 mg/m³ (respirable) | — |
| Lead dust | 50 μg/m³ | 50 μg/m³ | 50 μg/m³ |
Makerspace Context¶
Even with cabinet blasting and dust collection, exposure can occur during: - Media loading and unloading - Dust collector filter changes - Cabinet maintenance and cleaning - Cabinet seal failures during operation
Key Talking Points¶
- Particle size, not just composition, determines health risk
- Silicosis is 100% preventable by avoiding silica sand and using proper controls
- Even "safe" media generate respirable dust — controls are always needed
- Exposure limits represent maximum allowable — aim for zero exposure where possible
Learning Objectives (Concept Check)¶
- Explain the difference between inhalable, thoracic, and respirable particle fractions
- Identify the occupational diseases associated with abrasive blasting
- State the OSHA PEL for respirable crystalline silica
Last Updated: 2026-03-19