Our real time dust monitoring allows the Occupational Hygienists and your employees to see peaks in air exposures as well as dust settling times.
From this, you can see how long those pesky particles really stay in the air for, and how long after finishing a job you should keep your mask on for.
These peaks can at times be significantly higher than the Workplace Exposure Limits but not show up in the 8-hour Time Waited Averages. That may not be a problem from a ‘compliance’ viewpoint, but it can be from a health perspective.
Real time dust monitoring helps you manage exposure at source, contributes to your training programmes and supports employee understanding & compliance.
What is silica dust air monitoring?
Silica can be found in a variety of rocks, sand and clay used within the construction industry. However other industry fields will also have the potential for exposure to silica. Silica dust is created when we undertake cutting, drilling, grinding and polishing activities. Without good control measures and adequate respirable protective equipment (RPE) the fine silica dust can enter deep into your lungs. We call this fine dust respirable crystalline silica but it will also be referred to as silica or silica dust.
The Workplace Exposure Limit (WEL) for respirable crystalline silica dust is 0.1mg/m3 over a time weighted average over an 8 hour shift. To make sure you are compliant with this you will need to risk assess your exposure in accordance with the Control of Substances Hazardous to Health (COSHH) regulations. This can be achieved in a number of ways; however, the most common approach is to carry out silica dust monitoring in air. Personal sampling is carried out in accordance with the Health & Safety Executives Methods of the Determination for Hazardous Substances (MDHS) guidance. These are:
- MDHS 14/4 – General methods for sampling and gravimetric analysis of respirable, thoracic and inhalable aerosols
- MDHS 101/2 – Crystalline silica in respirable airborne dust
Silica dust monitoring is more than just the analysis of the samples and the reporting. As processed generated respirable crystalline silica is classed as a carcinogen, we have a legal duty to reduce this exposure to a low as reasonably practicable. This is why our Occupational Hygienist Consultants will spend their monitoring time on site looking for the improvement of control measures; training & educating the workers; and identifying the often over looked peak exposure to silica dust. Peak exposure to silica dust can lead to accelerated silicosis.
Further information can be found on the Health & Safety Executive web site: Cancer and Construction.
How do you monitor dust levels?
We carry out exposure monitoring for a number of reasons. Even though this list is not exhaustive we carry out exposure (in air) monitoring for:
- Supporting your COSHH risk assessment – assessing the effectiveness of control measures in place and assessing your compliance with the Workplace Exposure Limits
- Risk assess exposure to substances which present a series risk to health
- Where respiratory protection is our last resort in the Hierarchy of control, exposure monitoring will identify that your RPE is correct and provides good protection
- Establishing a compliant based Health Surveillance programme
You may be asked to carry out exposure monitoring after a H&SE has visited or you have been issued with an enforcement notice. At this stage it is important you engage with a competent person and not only with your exposure monitoring but for other areas too. This may include health surveillance, peak exposure, guarding, working at height/confined space, COSHH risk assessment to name a few.
How do you know what to monitor for?
All potential substances hazardous to health should be on your COSHH risk management register. Sometimes there are substances which are classified as respiratory and skin sensitisers, carcinogens and mutagens which you may be unfamiliar with. The majority of the time you can find these in Section 3: Composition/information in ingredients however, we recommend that you send through your safety data sheets to your Occupational Hygiene consultants to ensure that your are monitoring for the correct hazardous substances.
Examples for exposure monitoring:
- Welding/fabrication – Metal welding suite for analysis. Some compounds will require measurement at respirable level as well as total inhalable levels
- Construction/ground works – Respirable Crystalline Silica
- Stone masonry – Respirable Crystalline Silica and isocyanate-based adhesive
- Spray painting – Isocyanate and xylene/toluene-based paints. Dust can also be present during the preparation stage
- Food industry – Flour dust however, all food products with a protein has the potential to cause occupational work-based asthma. For example, gluten free flour-based products using potato, buck wheat, soya beans, tea leaves to name a few
- Composting activities – biohazards, such as viable particles, moulds and spores
- CNC manufacturing/Aerospace – working metal fluids
- Chemical Engineering – monitoring for specific compounds/elements and ten top 10 chemical analysis suites
- Manufacturing – general dust however there are often other substances hazardous to health which you may be unaware off
- Joinery/carpentry – wood based particulate matter and adhesives
- Education/Colleges – technical course will require exposure monitoring for their specific areas. For example Plumbing will require colophony and hot metal working fumes, Building courses will require respirable crystalline silica; Hair & Beauty for volatile organic compounds
The range of industries we cover is very varied with common substance used and not so common substances. We strongly recommend that you share you safety data sheets with your Occupational Hygiene consultant to ensure you are monitoring for the correct substances.
How long should you monitor for dust?
One of the main questions we are asked is how long we should be monitoring for? This is what the HSE recommend:
9 Air monitoring should be representative of the working periods of the individuals exposed. General guidance on workplace monitoring is given in Monitoring strategies for toxic substances (HSG173).
10 A longer sampling time ensures a heavier deposit and reduces potential weighing inaccuracies. So sampling times should be as long as is reasonably practicable:
(a) The maximum sampling time should be the entire shift, and 15 minutes for short-term samples. Task-specific sampling should cover the period of the task being performed.
(b) For an 8-hour time-weighted average (TWA) estimation of exposure, the minimum sampling period should be at least 25% of the shift, though it is preferable if sampling times are no less than four hours.
11 To avoid sampler overloading where dust concentrations are high, several consecutive samplers should be employed for comparison with workplace exposure limits (WELs), though enough information may be obtained from one sample.
MDHS 14/4 HSE
The priority should be covering a full shift as this will give an accurate exposure analysis in support of your COSHH risk assessment. It is important the set up at the start of shift and clean down at the end of the shift are covered as this is where the potential for peak exposure may occur. Occasionally certain task/activities are undertaken as part of the working day, so a careful monitoring and analysis strategy is agreed prior to sampling. Be cautious of monitoring only part of an 8 hour shift as this can lead to analysis which may not be representative of actual exposure.