In a work environment, the air may contain hazardous airborne contaminants that pose risks when breathed in.
During an eight-hour workday, an individual can inhale over 3,000 liters of air on average, and this can increase to 10,000 liters during strenuous physical activities. In many workplaces, this air may carry contaminants generated from various work activities or processes.
Airborne contaminants, which can manifest as vapors, dusts, particles, fibers, fumes, gases, or combinations thereof, contribute to the contamination of workplace air.
Contaminants are often released into the air during the use of hazardous chemicals or while conducting work processes such as:
- Employing rotating tools and parts, e.g., sanders, circular saws, routers, lathes, drills
- Performing hot processes, e.g., furnaces, soldering, brazing, welding
- Dealing with falling materials (solids, liquids, or powders), transferring powders, mixing
- Engaging in activities like spraying painting or abrasive blasting
- Undertaking processes involving the fracturing of solid material, e.g., crushing rock
- Conducting abrasion activities like sanding, grinding, polishing, fettling
- Participating in cleaning and waste handling tasks, e.g., sweeping or using compressed air for cleanup.
Various workplace activities or tasks can produce airborne contaminants, contributing to potential health risks.
Table 1: Examples of some common airborne contaminants and their properties (Courtesy of the Health and Safety Authority (HSA)).
| Name | Example |
|---|---|
| Gas | Carbon monoxide and carbon dioxide |
| Vapour | Acetone, ethanol, chloroform, styrene, petrol |
| Fibres | Asbestos and glass |
| Mist | Solution being sprayed (e.g. paint, steam, electroplating baths) |
| Fume | Solder or welding fumes |
| Dust | Flour dust, concrete/cement dust (generated by grinding cutting, crushing, drilling etc.) and silica from stone cutting. |
Impact on Health While the respiratory system employs defense mechanisms to eliminate certain contaminants, prolonged exposure to high levels or continuous exposure to low levels can overpower these defenses, leading to the development of diseases.
Various factors influence the impact of contaminants, including particle size, chemical composition, the concentration in the air, and individual characteristics of the person exposed to the contaminants.
Occupational exposure to certain airborne contaminants has the potential to cause or worsen a wide range of serious respiratory diseases including:
- asthma
- cancers of the respiratory system
- chronic obstructive pulmonary disease (also called COPD)
- mesothelioma
- silicosis.
Workplace Exposure Standards
In the workplace, exposure standards set the legal maximum concentrations of specific chemicals or substances to which workers may be exposed. There are three types of exposure standards:
Time-weighted average (TWA): This represents the maximum average airborne concentration of a substance over an eight-hour working day across a five-day working week.
Peak Limitation: This is the maximum or peak airborne concentration of a substance determined over the shortest analytically practicable period, not exceeding 15 minutes.
Short Term Exposure Limit (STEL): This is the time-weighted average maximum airborne concentration of a substance calculated over a 15-minute period.
Safe Work Australia publishes these exposure standards for Australia, and guidance on interpreting them is available in Safe Work Australia's "Guidance on the Interpretation of Workplace Exposure Standards for Airborne Contaminants."
It's essential to note that exposure standards may not protect all workers, as some individuals may experience health effects at levels below these standards. Even substances without published exposure standards, like diesel particulate matter (DPM), can be harmful, necessitating controls to minimize worker exposure to airborne contaminants.
Personal Air Monitoring:To determine airborne contamination levels or verify the effectiveness of controls, personal air monitoring can be conducted. A competent person, such as an occupational hygienist, can perform this monitoring.
Managing Exposures:
Identification:
- Consider tasks, processes, and technical information sources when identifying potential airborne contaminants.
- Utilize technical information from product labels, safety data sheets (SDS), equipment manuals, and suppliers.
- Refer to hazard-specific guidance for various substances.
Control the Risks:
- Focus on reducing the airborne concentration of contaminants rather than relying solely on respiratory protective equipment (RPE).
- Strategies include:
- Stopping or reducing exposure by using safer products or altering work processes.
- Implementing local exhaust ventilation (LEV) systems.
- Utilizing water or fine mist suppression for dust control.
- Isolating work processes outdoors or away from other workers.
- Using respiratory protective equipment (RPE) as a last resort, combined with higher-order controls.
- Combining multiple control measures for enhanced effectiveness.
In conclusion, effective risk management involves identifying, controlling, and minimizing exposures to airborne contaminants in the workplace.
Training:When dealing with airborne contaminants, it is crucial to educate workers about:
- The types of airborne contaminants that may be present in the workplace and the potential harm they can cause.
- The preventive controls in place and how to use them effectively.
Maintaining and Reviewing Controls:Even if the right controls are in position, it's essential to ensure their ongoing effectiveness. Consider the following:
- Regularly check when the controls were last inspected.
- Verify if workers consistently use the controls when required.
- Evaluate if there are more effective control measures available.
Two primary control measures requiring meticulous maintenance are local exhaust ventilation and personal protective equipment. Personal air monitoring by a competent person, such as an occupational hygienist, is necessary to confirm the effectiveness of control measures.
Controls should undergo a review at least once every five years or sooner in specific situations. For detailed information on when control measures should be reviewed, refer to section 5.2 of the Managing Risks of Hazardous Chemicals in the Workplace Code of Practice 2021.
Health Monitoring:Health monitoring serves to identify changes in an individual's health due to exposure to airborne contaminants. It becomes imperative when there is a significant risk to health.
Explore more about airborne contaminants that necessitate health monitoring to ensure a comprehensive approach to worker well-being.