Dust Hazards by Gary Rowe, CEO Safety Action
In this article we explore the safety issues associated with dust in the workplace, the different forms it takes, and explain the main health effects of excessive exposure to dust. In our follow-up (part 2) article we will describe how to protect yourself and others from the various forms of harmful dust.
What is dust?
Dust is a generic term that most of us use regularly, but do we understand what this means in relation to workplace safety and potential sources of harm? Dust is essentially solid particles scattered or suspended in air.
Where does dust come from?
The natural erosion of soil, sand and rocks and abrasion between materials (such as handling cardboard boxes or carpet) are the most common sources of dust in the workplace.
Wind can also introduce dust into the workplace from nearby areas and cause worker discomfort, eye irritation or a negative health reaction to pollens or microscopic organisms e.g. hay fever. High dust levels can also contribute to poor visibility and potential traffic accidents.
Dust generated by workplace activities
Dust generated from work activities include:
- Wood dust from carpentry sawing and sanding.
- Stone dust and silica dust from cutting or grinding stone.
- Toxic dusts and fumes from man-made timbers, such as formaldehyde being released from medium density fibreboard (MDF).
- Toxic dusts from cutting, grinding or heating heavy metals such Cadmium which is used extensively in electroplating and other processes.
- Dust released from abrasion between internal and external work surfaces, fittings and materials - such as when handling carpets or cardboard boxes or vehicles running over roadway surfaces.
The common sources of harmful or toxic dusts in the workplace include:
- Medium Density Fibreboard (MDF) used in office desks and kitchen tops.
- Asbestos products such as (AC) cement sheeting, insultation, tiles, fire door core (note: asbestos products were totally banned in Australia from 2004, so asbestos will more likely be found in older facilities).
- Toxic dust from gas and electric welding .
- Abrasion, grinding or heating of heavy metals such as lead or cadmium as used in electroplating.
- Nanoparticles e.g. microscopic particles with at least one dimension less than 100 micrometre (0.1mm).
Health effects of excessive dust exposure
The potential health effects of dust exposure can range from mild discomfort to serious or fatal illness, as outlined below:
- Mild discomfort and taste of grit in the mouth
- Irritation of the eyes
- Skin irritation or rash
- Coughing and breathing difficulty
- Asthmatic attack
- Chronic breathing problems
- Lung disease
- Poisoning from ingestion of toxic substances
- Tumours and cancers
Types of dust
For purpose of this article we are going to use a couple of simple definitions to categorise the diverse types of dust.
Particles in the broad size range from 0.001mm to 1 mm (e.g. 1 to 100 microns) are generally referred to as dust. Any larger particles are considered grit and will generally be too heavy to remain airborne. A human hair is about 0.1mm in diameter.
Respirable dust vs inhalable dust
Inhalable dust is commonly defined as the solid airborne material, up to 100 micrometres (0.1mm) in diameter, which enters the nose and mouth during breathing and deposits in the upper respiratory tract.
Respirable dust is commonly defined as the smaller particles, less the 10 micrometres (0.01mm), that is capable of reaching deep into the lungs where the gas exchange takes place e.g. into the alveolar.
Toxic dust vs non-toxic dust
Some dusts can contain harmful substances, or they may consist of fibres or crystalline structure which are capable of reaching deep into the lungs and if insoluble can cause irritation, tumours or malignant tumours (e.g. cancer) to develop.
What is nuisance dust?
Inhalable dust which has no particular toxic properties is typically referred to as nuisance dust. The ACGIH (American Conference of Governmental Industrial Hygienists) describe airborne inhalable particulates which have little or no harmful effect on the lungs and do not produce significant disease or harmful effects when exposures are kept within reasonable levels as nuisance dust.
Is nuisance dust harmful?
The short answer to this question is “anything other than clean fresh air is not good for our lungs.”
Of course, it is not possible in the real world to never breathe in dust, as it is present in the air everywhere, even if you can’t see it, and dust accumulates on surfaces, even in the cleanest work environments.
Legislation and codes
Legislation in each state sets exposure limits for known hazardous chemicals.
Nuisance dust has no formal exposure limit in Australia, but the Australian Institute of Occupational Hygienists (AIOH) have recommended nuisance dust exposure be limited to:
- Inhalable Dust – 5mg/cubic metre (8hr TWA *), and
- Respirable Dust (which can reach the lungs) – 1mg/cubic metre (8hr TWA).
* TWA - Time weighted average
For a full copy of this article or our self-assessment checklist give us a call, or email Zara at email@example.com.