Dust Exposure - The Complete Guide
Posted 8th May 2020
Every year, thousands of workers are made ill from exposure to dust in the workplace that could result in an increase of lung diseases including Occupational Asthma, COPD and even Cancer.
Dust is not always an obvious health hazard in the workplace as the particles which cause the most damage are often invisible to the naked eye, and the health effects of exposure can take many years to develop.
Dust can be a problem in almost every industry. The hazards of dusts can be life threatening and come in many different forms including stone, cements and masonry dust, wood dusts, grain and flour dusts, cotton and wool process dust, asbestos, diesel engine emmissions and general nuisance dust.
Exposure to all such dusts needs to be prevented or, at least adequately controlled if the dust is one of the main aspects of an employee’s job or working environment.
Do you have a problem with Dust in your business?
If you think dust could be a problem, ask yourself the following questions:
Are the materials you use naturally dusty?
Does the work you do create dust mechanically or other means?
Is dust liable to be disturbed on a regular basis?
Here are some examples of activities that can create dust – do you do any of the following?
- Filling bags or emptying them into skips or other containers
- Weighing loose powders
- Cutting of materials
- Sieving and screening operations
- Conveying materials by mechanical means or by hand
- Stockpiling large volumes of processed materials
- Crushing and grading
- Activities involving diesel engines
- Milling, grinding, sanding down or other similar operations
- Cleaning and maintenance work
- Clearing up spillages
The workplace exposure limit (WEL) for general respirable and inhalable dust is 4mg/m3 and 10mg/m3 respectively based on an eight-hour working shift. Other more specific types of dust have lower exposure limits as they are considered to be more harmful.
When considering exposure limits for a particular type of dust it is also important to consider whether or not it has been classed as a respiratory sensitiser or carcinogen and therefore should be given special considerations. For these types of dust, it is a requirement to reduce levels as low as reasonably practicable regardless of the measured exposure levels.
Inhaling aerosol particles
Materials hazardous to health often occur in the workplace in the form of aerosols. The term ‘aerosol’ is used to describe any suspension of particles in air, whether they constitute dust, fibres, fume, smoke or liquid droplets which consist of a wide range of particle diameters.
The behaviour, deposition and fate of any particle after entry into the human respiratory system are determined by the chemical nature and the size of the particle in question.
For occupational hygiene purposes it is important to consider the concentration and the size fractions present. It is possible to define aerosol size fractions that relate to the region of the respiratory tract where they deposit.
These are the inhalable, thoracic and respirable size fractions:
(a) Inhalable fraction – this approximates to the fraction of airborne material that enters the nose and mouth during breathing and is therefore available for deposition anywhere in the respiratory tract.
(b) Thoracic fraction – this is the fraction of inhaled airborne material penetrating beyond the larynx.
(c) Respirable fraction – this is the inhaled airborne material that penetrates to the lower gas exchange region of the lung.
As previously mentioned there are a number of dust types that require special considerations when carrying out a risk assessment as follows:
Respirable Crystalline Silica (RCS)
Silica is a natural substance found in most rocks, sand and clay and in products such as bricks and concrete. Silica is also used as filler in some plastics. In the workplace these materials create dust when they are cut, sanded, carved etc. Some of this dust may be fine enough to breathe deeply into your lungs and cause harm to your health. The fine dust is called Respirable Crystalline Silica (RCS) and is too fine to see with normal lighting. The amounts needed to cause ill health are not large. (100 x less than the general dust exposure limits).
Assessing the risk from this type of exposure should take into consideration the fact that any mesaurements obtained require a specific sampling and analysis technique different to general dust monitoring.
Click to learn more about RCS exposure
Flour dust is a daily occurrence in facilities including plant bakeries, craft bakeries, semi-automated craft bakeries, in-store bakeries, pizza and pastry manufacturing facilities and biscuit manufacturing which means that approximately 95,000 people working in the UK baking industry encounter it daily.
Flour dust is classed as a respiratory sensitiser and therefore employers should make all efforts to reduce exposure to as low as reasonably practicable. Flour dust does not have a respirable exposure limit only a total inhalable exposure limit of 10mg/m3.
Flour dust may look harmless, well in fact it can cause serious lung diseases like Asthma which can result in attacks of breathlessness and tightness in the chest.
Other side effects of using flour and inhaling its dust include:
- Irritation to the eyes (conjunctivitis), resulting in watering and painful eyes
- Irritation to the nose (rhinitis), resulting in a runny nose
- Occupational dermatitis, resulting in redness, itching and blistering of the skin
Once a person becomes sensitised to this form of dust, exposure to even a very small amount of it can bring on an asthmatic attack, it is then possible that the person will never be able to work in a flour dust environment again.
Carpenters and joiners are four times more likely to get asthma and other lung diseases due to working closely with wood dust on a very regular basis.
Other conditions can also develop particularly from hardwood dust such as Cancer - particularly of the nose which is why it’s very important to be aware of the workplace exposure limits and assess your workforce on a regular basis.
Both hardwood and softwood dusts have a total inhalable Workplace Exposure Limit (WEL) of 5mg/m3 which must not be exceeded. These limits are created based on the amount of dust in the air, averaged over a typical eight-hour working day. However, you must reduce exposure to wood dust to as low as reasonably practicable as both hard and soft wood dusts act as respiratory sensitisers.
Providing dust extraction (also known as local exhaust ventilation or LEV) at woodworking machines to capture and remove dust before it can spread is imperative.
It will be the responsibility of the employer to keep the extraction system properly maintained and working correctly (it is a legal requirement to have it examined by a competent person at least every 14 months).
Never sweep up or use compressed air lines as this will disturb the dust and allow it to become inhaled. Always clean up using a suitable industrial vacuum cleaner which is fitted with a HEPA filtration system.
Engine Emmissions (DEEEs)
DEEEs stands for Diesel Engine Exhaust Emissions that contain a complex mixture of gases, vapours, liquid aerosols and particulate substances. These substances are the products of combustion.
Exhaust emissions from diesel engines are usually more visible than those emitted from petrol engines because they contain over ten times more soot dust. The soot particulates in DEEEs have hundreds of organic substances adsorbed onto their surface, some of which are potentially more harmful to health than others. The soot content in DEEEs varies from 60% to 80% depending on the fuel used and the type and condition of the engine.
When planning any monitoring startegy or risk assessment for DEEEs it is important to not only measure soot dust levels but a range of other substances assocaited with this type of emmissions.
How can Euro Environmental help?
Our consultants are here to help you and can develop and implement monitoring strategies to identify if maximum exposure limits are being exceeded with respect to general dust or those dusts assigned with specific WEL's in the workplace.
Our team will advise on appropriate measures to be taken to reduce the risk of exposure and ensure you comply with the Control of Substances Hazardous to Health Regulations.