Sysco Environmental Ltd recently conducted a thorough assessment of dust exposure at a construction training facility focused on trades like carpentry and brickwork. This study aimed to understand the airborne characteristics of wood dust particles, such as their size, suspension time, and the risk of exposure to workers. In fields like carpentry, where dust is generated constantly, inhaling dust over long periods can lead to serious respiratory issues. By following COSHH (Control of Substances Hazardous to Health) guidelines, this assessment supports creating a safer, healthier working environment.
Tutors and apprentices working with softwood and hardwood produce varying sizes of dust particles during tasks like sawing, sanding, and assembling. Around 90% of the wood used in the carpentry area is softwood, while the remaining 10% is hardwood, creating a mix of airborne particles. These particles are categorised based on their aerodynamic properties, which affect their behaviour in the air and potential health risks. The key classifications are inhalable, thoracic, and respirable fractions.
- Thoracic Fraction: Particles under 30 microns that penetrate past the larynx and into the trachea and bronchi.
- Respirable Fraction: These are the smallest particles, under 10 microns, capable of reaching the alveoli in the lungs where gas exchange occurs. They pose the greatest risk for chronic respiratory conditions due to their deep penetration.
Inhalable Particles (10–100 microns): Larger particles generally settle faster, usually within seconds to minutes in still air. However, in spaces with high air movement, they can remain airborne longer.
Settling Speed and Air Movement: Larger particles, between 50–100 microns, typically settle within seconds to a minute in still air, while 10-micron particles can take up to 8 minutes. Active ventilation reduces suspension time and helps prevent dust build-up.
In a workplace setting where wood dust is constantly generated, good ventilation and dust control measures are essential. Without them, respirable particles—those most harmful to respiratory health—may stay airborne for hours, raising the risk of inhalation. Local exhaust ventilation (LEV) can play a significant role in reducing airborne dust duration by capturing particles near the source.
- Static Sampling: Monitors were set near high-dust equipment like chop saws and along key areas in the facility to gauge background dust dispersion.
- Chronic Exposure: With repeated exposure to fine, respirable particles, risks increase for conditions like asthma, chronic bronchitis, and possibly COPD. Hardwood dust is classified as a carcinogen, heightening cancer risks with prolonged exposure.
- Recommendation: Enhance LEV systems with regular maintenance and add flexible hoses for targeted extraction. This will improve dust capture at the source, reducing airborne concentrations of both inhalable and respirable dust particles, and limiting how long particles stay suspended in the air.
- Recommendation: Face-fit testing ensures that RPE fits correctly, especially important for high-dust activities. Designating RPE zones near carpentry equipment will reinforce RPE use in critical areas, providing consistent protection against airborne particles.
- Recommendation: Switching to vacuum cleaning with HEPA filters or wet cleaning methods will prevent dust clouds from forming. If dry sweeping is necessary, RPE should be worn to reduce inhalation risks, especially in high-use areas.
Tomas Gabor
0800 433 7914