What is in the dust
HSE groups construction dust into three types: silica dust, wood dust, and lower-toxicity dust from materials with little or no silica, such as gypsum in plasterboard, limestone, marble and dolomite. Plasterers and drylining teams can meet several of these in the same week.
- Gypsum plasters and plasterboard. Gypsum (calcium sulfate) is what plasterboard is made from and the main ingredient of gypsum plasters.
- Jointing and filling compounds. These are often based on gypsum, limestone (calcium carbonate) or both. Some also contain other minerals such as mica, and small amounts of quartz can be present as an impurity. The safety data sheet tells you what is in the product you are using.
- Masonry backgrounds, renders and sand and cement. HSE says silica is found in most rocks, sand and clay, and is a major part of bricks, tiles, concrete and mortar. Cutting, chasing, drilling or grinding these materials creates respirable crystalline silica (RCS) dust. Cement powder is also a respiratory irritant.
Why it matters
HSE says regular exposure to construction dust can lead to lung cancer, asthma, chronic obstructive pulmonary disease (COPD) and silicosis, and that these diseases cause permanent disability and early death. Silica is the most serious: HSE believes over 500 construction workers die from exposure to silica dust every year.
Lower-toxicity dust such as gypsum is not harmless. Sanding is often done in small rooms or overhead, which puts the dust straight into your breathing zone, and HSE found that sanding taped plasterboard joints without controls quickly produces peaks of around 10 mg/m³, well above the 4 mg/m³ limit for the fine respirable dust.
Workplace exposure limits
Workplace exposure limits (WELs) are set out in HSE’s EH40/2005. The current edition dates from 2020, and when this guide was checked in October 2026 the limits below had not changed. All are 8-hour time-weighted averages.
| Substance | Inhalable dust | Respirable dust |
|---|---|---|
| Gypsum | 10 mg/m³ | 4 mg/m³ |
| Plaster of Paris | 10 mg/m³ | 4 mg/m³ |
| Limestone | 10 mg/m³ | 4 mg/m³ |
| Portland cement | 10 mg/m³ | 4 mg/m³ |
| Mica | 10 mg/m³ (total inhalable) | 0.8 mg/m³ |
| Respirable crystalline silica | No inhalable limit | 0.1 mg/m³ |
Under COSHH, dust present at more than 10 mg/m³ inhalable or 4 mg/m³ respirable, averaged over 8 hours, counts as a substance hazardous to health even if it has no WEL of its own. A WEL is a maximum, not a target, so aim to keep exposure as low as you can.
Make less dust in the first place
The best control is not creating the dust. For plasterboard joints, HSE’s first suggestion is to use other methods that avoid the need for sanding. A well-applied finish needs less rubbing down. When mixing, tip bags slowly and low into the water, and mix in a ventilated area away from other people.
On-tool extraction
- Use sanders and power tools with on-tool extraction connected to an extraction unit. HSE’s construction dust guidance says to use an M or H class unit and not a general commercial vacuum.
- HSE accepts that an L class unit is only suitable for lower-toxicity dust such as the gypsum in plasterboard. If a compound or background contains silica, or you are not sure, use M or H class.
- Check that the extraction flow rate suits the tool, that hoses are tight and undamaged, and that the low-flow indicator works.
- Carry out formal maintenance checks at least once a week, and have a competent person carry out a thorough examination and test at least every 14 months.
- Use sanding discs or pads with enough holes to let the dust through to the extraction.
Done properly, extraction makes a big difference. In HSE’s example of sanding taped plasterboard joints, extraction kept dust low enough that RPE was not needed for that task.
Wet methods
For cutting or chasing masonry backgrounds, water suppression is an alternative to extraction. HSE stresses that water must be supplied throughout the work, because just wetting the material beforehand does not work. Make sure the water does not create slip or electrical hazards.
Respiratory protective equipment
RPE is the last line of defence, used alongside extraction or water where dust is still likely. HSE says the general level of protection needed for construction dust is an assigned protection factor (APF) of 20, for example an FFP3 disposable mask or a half mask with a P3 filter. For longer jobs, HSE suggests powered RPE such as a TH2 hood or helmet.
- Tight-fitting masks must be face-fit tested by a competent person. The best time is when the RPE is first chosen, and each type of mask a person uses needs its own test.
- Stubble and beards stop a tight-fitting mask sealing, so wearers must be clean-shaven. If someone needs to keep a beard, for example for religious reasons, use RPE that does not rely on a face seal.
- Keep RPE clean, store it away from dust and change filters as the manufacturer instructs.
Clean up with a vacuum, not a brush
HSE advises avoiding dry sweeping where possible, because it can push large amounts of dust back into the air. For fine material, use vacuum attachments fitted to an H or M class unit. For small amounts, damp down and use a brush, shovel and bucket, and for regular site cleaning, damp down first with a water spray. Clean up as you go so dust does not build up and spread to other rooms and trades.
Health surveillance and monitoring
HSE says that where workers are regularly exposed to RCS and there is a reasonable likelihood that silicosis may develop, health surveillance must be provided. That can apply to plasterers and drylining teams who regularly chase, cut or grind masonry. You may need advice from an occupational health professional, and you might need dust monitoring to check that your controls are working.
Wet cement can cause dermatitis and serious burns. Where people work with cement-based products, HSE recommends that a responsible person checks the condition of their skin when they start and periodically after that, and keeps records.
Put it in the RAMS
Your plastering or drylining RAMS should list the tasks that create dust, the extraction or water controls for each, the class of extraction unit, the RPE and who has been face-fit tested for it, and how the area will be cleaned. Have your competent person check it against the actual job before work starts.
Frequently asked questions
Is plasterboard dust as dangerous as silica dust?
No. HSE treats the gypsum in plasterboard as a lower-toxicity dust, while respirable crystalline silica is far more harmful and has a much lower exposure limit. Gypsum dust is still hazardous in high amounts, and masonry backgrounds and some compounds contain silica, so you need to control both.
What class of extractor do I need for sanding jointing compound?
HSE generally recommends M or H class units for construction dust and says an L class unit is only suitable for lower-toxicity dust such as gypsum. Check the safety data sheet for the compound, and use M or H class if it contains silica or you are not sure.
Do drylining teams need face-fit testing?
Anyone who wears a tight-fitting mask, such as an FFP3 disposable or a half mask, needs to be face-fit tested for that model and be clean-shaven when wearing it. If extraction keeps the dust low enough that RPE is not needed, record that in the risk assessment so the decision is clear.