COSHH guide · Cleaning chemicals

Cleaning chemicals and COSHH

What makes bleach, descalers, degreasers and disinfectants hazardous, which products must never be mixed, and what COSHH asks of cleaning, facilities and trades teams.

Free COSHH assessment template →

Published 5 October 2026 · Checked against legislation.gov.uk and HSE on 5 October 2026

Do cleaning chemicals come under COSHH?

Yes: any cleaning product that meets the criteria for a health hazard class under GB CLP is a substance hazardous to health, so COSHH applies to it. That can include bleach, descalers, toilet, oven and drain cleaners, degreasers and disinfectants. HSE’s rule of thumb for cleaners is simple: a hazard symbol on the packaging means a hazardous substance.

The harm comes in four ways. Corrosive products burn skin and damage eyes. Detergents and wet work cause dermatitis. Some ingredients cause skin allergies and asthma. And some products give off toxic gas when mixed: bleach with an acid releases chlorine, and bleach with ammonia releases chloramines.

COSHH requires the employer to assess the risk before the work, to prevent or adequately control exposure, and to inform, instruct and train the people using the products. The contents and hazards of a decanted bottle must be clearly identifiable. Solvent-based cleaners add a fire risk, which falls under DSEAR.

The safety data sheet for any product comes from its supplier: ask them for it. The assessment is yours, and the cleaning risk assessment template shows the controls for a commercial cleaning contract.

Cleaning chemicals and what makes them hazardous

From HSE and UKHSA

The product types cleaning, FM and trades teams use most, and the hazards HSE and UKHSA describe for each. Strengths and classifications vary, so section 2 of each product’s data sheet is the guide to that product. Several points come from HSE’s CAIS22, a sheet on cleaning substances written for the hospitality industry, and are marked as such.

Common cleaning chemicals, what they are used for and their main hazards, from HSE and UKHSA guidance
Product type	Typical use	Main hazards	What to watch
Bleach and other chlorine-releasing products (sodium hypochlorite)	Disinfecting washrooms, toilets, drains and hard surfaces	UKHSA describes sodium hypochlorite as corrosive: it can irritate or burn the skin and damage the eyes, more so at higher strengths. The label gives each product’s own classification.	UKHSA puts household bleach at about 5% sodium hypochlorite, sometimes up to 10%, and industrial bleach at up to 50%. GB CLP names sodium hypochlorite as an example for EUH031, “Contact with acids liberates toxic gas”.
Acid descalers and toilet cleaners	Limescale, toilets, urinals and showers	Many are corrosive or irritant to the skin and eyes; section 2 of the data sheet says which	HSE’s CAIS22 says bleach mixed with acidic toilet cleaners gives off harmful gases. HSE’s COSHH essentials sheets SR2 and SR4 say to avoid products containing hydrofluoric acid.
Alkaline degreasers, oven cleaners and drain cleaners	Kitchens, grease, ovens and blocked drains	Many are corrosive and burn the skin and eyes on contact	HSE’s CAIS22 warns that products such as oven cleaner can cause breathing problems if oversprayed, sprayed onto hot surfaces or used without ventilation. SR2 says caustic soda can erupt when mixed with water and splash the eyes.
Disinfectants and sanitisers	Surfaces, washrooms, kitchens and touch points	Some contain ingredients that are toxic by inhalation or through the skin, or are sensitisers	Many disinfectants are biocidal products: use them only for what the label says they are authorised for. SR2 and SR4 say to avoid toxic or sensitising biocidal concentrates, giving quaternary ammonium compounds as an example, unless the sanitation programme identifies an absolute requirement.
General-purpose detergents and washing-up products	Floors, surfaces and general cleaning	Often mild, but repeated contact dries and irritates the skin	HSE’s G403 lists soaps and cleaning products, and wet work, among the main causes of occupational dermatitis.
Solvent-based cleaners and degreasers	Removing grease, adhesive, ink and paint residue	Vapour, skin irritation and dryness. Many are flammable.	Ventilation, no ignition sources, and storage under DSEAR. See solvents.

Searching for a “COSHH sheet” for a branded product usually means its safety data sheet. Only the supplier can provide it, and HSE’s CAIS22 notes that suppliers of hazardous substances are required by law to provide safety information. Read how to read a safety data sheet, then record what it says in your own assessment. Sources: HSE CAIS22, SR2, SR4, G403 and UKHSA’s sodium hypochlorite guidance.

Never mix cleaning products

Toxic gas

UKHSA says breathing the gases formed when bleach is mixed with acidic solutions, or alkaline ones such as ammonia, is the most frequent way adults are exposed to it. HSE’s CAIS22 puts it in four words: never mix cleaning substances.

Bleach and acid: chlorine gas

Bleach mixed with an acid releases chlorine. Acid descalers, acidic toilet cleaners and limescale removers are the usual culprits. UKHSA names vinegar as an acid too.

UKHSA, sodium hypochlorite; HSE SR2

Bleach and ammonia: chloramines

Bleach mixed with a cleaning product containing ammonia produces chloramines, which UKHSA describes as highly irritating to the respiratory tract. Hazardous ingredients are listed in section 3 of the data sheet.

UKHSA, sodium hypochlorite

Bleach and anything else

HSE’s SR2 and SR4 say never to add any other chemical to a concentrate that contains bleach. Under GB CLP, a mixture sold to the general public with more than 1% active chlorine carries EUH206: “Warning! Do not use together with other products. May release dangerous gases (chlorine)”. Products sold only to professionals need not carry it, so its absence does not make a product safe to mix.

HSE SR2 and SR4; GB CLP Annex II, section 2.6

What the gas does

For chlorine, UKHSA describes burning eyes and throat, coughing and a sore throat at low levels. More exposure brings breathing difficulty and swelling of the airways, and high levels can be fatal. Irritation usually starts at once, but UKHSA notes that breathlessness can follow after a delay of up to 15 hours.

UKHSA, sodium hypochlorite toxicological overview

Mixing on the surface

Products meet in the toilet bowl, the drain or the bucket as easily as in a bottle. Our practical advice: one product per job where possible, rinse or flush between products, and never top up one product’s bottle or bucket with another.

Our practical advice, applying HSE’s “never mix”

If gas is given off

UKHSA’s advice is to move away from the source and to seek medical advice after breathing it in. COSHH requires emergency procedures, including first aid, unless the assessment shows only a slight risk from the quantities present and the controls are sufficient.

UKHSA; COSHH regulation 13(1) and (4)

UKHSA also notes that a small proportion of people exposed to chlorine go on to have a long-term sensitivity to inhaled chemicals. Store bleach away from acids so the two cannot meet in a leak either: see COSHH storage.

What COSHH asks for cleaning products

COSHH 2002

There are no separate cleaning regulations. The general COSHH duties apply to a bottle of descaler as they do to any other hazardous substance. Each row says whether it is law or HSE guidance.

Which products are covered

The law covers any substance or mixture that meets the criteria for a health hazard class under GB CLP, whether or not it is actually classified. It also covers anything with a workplace exposure limit, and anything that creates a risk to health because of its properties and the way it is used. A product hazardous only because it is flammable falls outside COSHH; DSEAR covers that risk.

Regulation 2(1), “substance hazardous to health”, (a), (b) and (e); regulation 5(1)(b)

Assess before the work

A suitable and sufficient assessment comes before the work. It considers the hazards, the supplier’s data sheet, the level, type and duration of exposure, and the risk from more than one substance in combination. Employers with 5 or more employees record the significant findings.

Regulation 6(1), (2) and (4)

Substitute first

Substitution is the preferred way to prevent exposure: a milder product, or a process that does without the chemical. HSE’s skin guidance says to use the mildest cleaning chemicals that will do the job, and its CAIS22 says to ask the supplier for a safer alternative.

Regulation 7(1) and (2); HSE, skin at work FAQs; HSE CAIS22

Then control, in order

Work methods and equipment come first, then control at source and good organisation, with PPE last and in addition. The measures include safe handling and storage, the least quantity on site, general ventilation and adequate washing facilities.

Regulation 7(3) and (4)

A higher standard for asthma causes

For a product labelled H334, or a substance in section C of HSE’s Asthmagen? list, exposure must also be as low as reasonably practicable. The same applies to any other substance the assessment shows may cause occupational asthma. Section C includes the disinfectants glutaraldehyde and chloramine-T.

Regulation 7(7)(c)(ii); HSE, asthma substances

Gloves and eye protection

PPE must be suitable for the purpose, properly stored, checked at suitable intervals and replaced when defective. Contaminated PPE comes off on leaving the work area and is kept apart from clean clothing.

Regulations 7(9) and 9(5) to (7)

Information, training and labelled containers

Each employee liable to be exposed gets suitable information, instruction and training, including the product names and risks, access to the data sheets and the precautions. A container not labelled under other law must have its contents and hazards clearly identifiable.

Regulation 12(1), (2) and (5)

Cleaning can be construction work

CDM 2015 counts the maintenance of a structure as construction work, including cleaning with water or an abrasive at high pressure, or with corrosive or toxic substances. Jet washing a building or chemically cleaning its brickwork are examples. CDM then applies alongside COSHH.

CDM 2015, regulation 2(1), “construction work”

HSE’s CAIS22 adds that it is not enough to hand out safety data sheets: employees have to understand the hazards and the controls. More on the duties in the COSHH Regulations explained, and on CDM in the CDM 2015 guide.

Diluting, decanting and using cleaning chemicals

The stages follow a product from the delivery to the end of the shift. The points are from HSE’s cleaning guidance, CAIS22 and the COSHH essentials sheets SR2, SR4 and SR24, unless marked as ours.

Choose the product

Stop using products that are not needed. Choose the mildest one that does the job, ready-diluted products in smaller containers, and tablets, granules or single-use sachets in place of concentrates.

NoteHSE’s sheets say to avoid products containing hydrofluoric acid, and sensitising or toxic biocidal concentrates unless the cleaning programme needs them.

Dilute

Read the label and dilute as it says. Add the concentrate to the water, never the water to the concentrate, unless the instructions say otherwise. Make up solutions for immediate use only.

NoteUse pumps or syphons rather than pouring from heavy bulk containers. Dispense powders with a scoop, never by hand.

Decant and label

Keep products in their original labelled containers where possible. Where decanting, CAIS22 says the container should be of a suitable material, clean and clearly marked with the contents, the hazards and the instructions for use. Never decant a concentrate into an unlabelled container.

NoteNever use a food or drink container. Keep disinfectant and other biocide stock in its original container, which HSE says the law requires. Decant only a working solution, made up for immediate use as SR2 and SR4 say, and as the product label allows.

Clean with distance and air

Use a mop with a handle rather than a cloth, and work in a well-ventilated area. An open window may be enough; switch mechanical ventilation on and check it works.

NoteNever spray aerosols or oven cleaner onto hot surfaces. Wear eye protection when cleaning at eye level or above.

Protect skin and eyes

Wear the gloves and eye protection the label and data sheet set out, with goggles or a visor where splashes are possible. Check rubber gloves for holes, tears and thin patches before use.

NoteAvoid latex gloves. Report any irritation or allergy from gloves. See occupational dermatitis.

Store

Store products securely, in a cool, dry, ventilated place, lids on and labels facing forward. Keep acids apart from alkalis, bleach apart from acids, and corrosive products on lower shelves.

NoteAway from heat, sunlight, food and members of the public. See COSHH storage.

Deal with splashes and spills

Wash a splash off skin or eyes at once with plenty of water, and seek medical advice if irritation persists. For bleach, UKHSA advises at least 10 to 15 minutes of washing, then medical advice. Clear spills immediately under a set procedure, with the data sheets where staff know to find them.

NoteWhere mains tap water is not readily available, CAIS22 says to provide at least a litre of sterile water or sterile saline (0.9%) in sealed containers for eye irrigation.

Report and review

Workers report skin problems, breathing problems, headaches or nausea to their supervisor at once. Supervisors check products are used and stored as the assessment says.

NoteCOSHH requires the assessment to be reviewed regularly, and at once where there is reason to suspect it is no longer valid.

HSE’s sheets say respiratory protection is not normally needed for diluting or surface cleaning where general ventilation gives a good through draught. It may be needed for a spill, depending on its size and location. Tight-fitting RPE needs a face fit test.

Skin, breathing and health checks

HSE names cleaning among the high-risk groups for both occupational dermatitis and occupational asthma. The full detail is on each disease page; this is what matters for cleaning products.

Dermatitis

HSE’s key messages for cleaners: hands wet for long periods or frequently wet can lead to dermatitis, and some ingredients cause skin allergies. HSE’s approach is to avoid contact, protect the skin and check it for early signs.

HSE, COSHH and cleaners; HSE G403

Gloves for cleaning

HSE’s skin guidance says strong reusable rubber gloves should be fine unless a product’s label says otherwise. Its SR2 and SR4 sheets accept single-use nitrile gloves, thrown away each time they come off. Either way, check section 8 of the data sheet, and choose non-latex gloves, as CAIS22 says latex is known to cause reactions. Cotton liners and short glove breaks help with sweat.

HSE, skin at work FAQs; HSE SR2, SR4 and CAIS22

Asthma

HSE’s G402 lists cleaning products among the main causes of occupational asthma, and cleaning services among the high-risk groups. Look for H334 on the label: “May cause allergy or asthma symptoms or breathing difficulties if inhaled”.

HSE G402; GB CLP Annex III

Irritant gases and existing asthma

Some products do not cause asthma but irritate the airways. HSE gives chlorine as an example of an irritant that can trigger attacks in people who already have asthma. HSE’s CAIS22 links breathing problems to overspraying and poor ventilation.

HSE, asthma overview

Health surveillance

The law requires it where an identifiable disease may be related to the exposure, is reasonably likely in the work, and can be detected by a valid, low-risk technique. HSE’s G403 and G402 say to consider it for products labelled H315, H317 or H334, among other triggers. HSE’s cleaning sheets SR2 and SR4 put it more firmly: they say surveillance is required where workers use a product labelled as a skin or respiratory sensitiser.

Regulation 11(1) and (2)(b); HSE G402 and G403

Reporting under RIDDOR

A doctor’s diagnosis of occupational dermatitis is reportable where the work involves significant or regular exposure to a known skin sensitiser or irritant. Occupational asthma is reportable on the same terms for a known respiratory sensitiser. A chemical burn that significantly damages the eyes or airways is a reportable specified injury.

RIDDOR 2013, regulations 4(1)(e) and 8(c) and (e)

How skin and breathing checks are run is set out in health surveillance. The diseases themselves are covered in occupational dermatitis and occupational asthma.

COSHH training for cleaners

Regulation 12 applies to a cleaner liable to be exposed exactly as to any other employee. The training covers the products in use by name and what each can do to health. It also covers where the data sheets are, the significant findings of the assessment and the precautions.

HSE’s CAIS22 adds the practical points. People need to know when and how to wear and replace gloves and eye protection, and the first aid for splashes. They also need the spill procedure and how to report symptoms. Where staff do not have English as a first language, CAIS22 says the employer must make sure they clearly understand. Posters and pictures help.

Many disinfectants are biocidal products. HSE’s biocides guidance says professional users must have the information, instruction and training to use them, and must read and follow the label. The full content of COSHH training is set out in COSHH training, and short briefings in the toolbox talks.

COSHH in Unibuild

Written, signed and kept,
tied to the job that uses it.

In Unibuild, a COSHH assessment is written once and operatives read and sign it on their phone, the same way as a RAMS. The AI builds a draft from the supplier’s safety data sheet and checks an assessment before it goes out. A person reviews and finalises every one.

Each substance holds its data sheet and supplier, linked to the jobs, materials and purchase orders that use it. Review dates are tracked and every version is kept. When an auditor or a principal contractor asks for the COSHH register, it is a search, not a spreadsheet.

Book a demo → The health and safety module

Signed on the phone by every operative, the same way as a RAMS
Drafted by AI from the safety data sheet, and checked before issue
A data sheet for every substance, tied to the job through materials and purchase orders
Review dates tracked and every version kept
COSHH e-learning, with the certificate on the training matrix

Free COSHH templates

Free to use and reuse, no sign-up

Free downloadCOSHH assessment templateOne substance per assessment: the hazards from the safety data sheet, who is exposed and how, the controls, PPE, storage, spills and first aid. Free downloadCOSHH register templateEvery hazardous substance on site or in the van, with its data sheet date, assessment reference, location and review date. Free downloadCOSHH risk assessment, pre-filledA risk assessment and method statement for work with cement, solvents, resins, dusts and fume on site, filled in and editable. Free downloadCOSHH symbols posterThe nine hazard pictograms and what each one means, for the store, the van or the welfare cabin. A4 or A3.

Asked most often

Cleaning chemicals: common questions

What happens if you mix bleach and ammonia?

Bleach mixed with a product containing ammonia produces chloramines. UKHSA describes them as highly irritating to the respiratory tract. Irritation usually starts at once, and UKHSA notes that breathlessness can follow up to 15 hours later. Never mix bleach with any other product. If it happens, move away from the fumes and seek medical advice.

What happens if you mix bleach with acid or toilet cleaner?

Chlorine gas is released. Acid descalers, acidic toilet cleaners, limescale removers and even vinegar are acids. Chlorine burns the eyes and throat and causes coughing; higher levels cause swelling of the airways and can be fatal. Keep bleach and acid products apart in use and in storage, and rinse or flush between products.

Do cleaning products need a COSHH assessment?

Yes, where the product meets the criteria for a health hazard under GB CLP. HSE’s rule of thumb for cleaners: a hazard symbol on the packaging means a hazardous substance. The assessment uses the label and the data sheet. It covers dilution, use and storage, who is exposed, the gloves and eye protection, and what the product must never meet.

Where do I get a COSHH sheet for a cleaning product?

What people call a COSHH sheet is usually the product’s safety data sheet. It comes from the supplier: ask them for the current version. The data sheet describes the product; the COSHH assessment, which you write, says how your team will use it safely on your jobs.

Can you decant cleaning chemicals into spray bottles?

Yes, if the bottle is suitable for the product, clean, and clearly labelled with its contents, hazards and instructions for use. COSHH requires the contents and hazards of any container not labelled under other law to be clearly identifiable. Never use a food or drink container. Disinfectant stock stays in its original container, as HSE says the law requires for biocides; decant only a working solution for immediate use.

Do you add water to the chemical or the chemical to water?

Add the concentrated chemical to the water, never the water to the concentrate, unless the product instructions say otherwise. HSE gives this in its CAIS22 sheet and in its COSHH essentials sheet SR2 on diluting concentrates. Caustic soda can erupt when mixed with water and splash the eyes, so wear eye protection when diluting.

What gloves should cleaners wear?

The gloves the product label and data sheet set out. HSE’s skin guidance says strong reusable rubber gloves should be fine unless a product label says otherwise, and its COSHH essentials sheets accept single-use nitrile gloves. Choose non-latex gloves, check them for holes before use, and use cotton liners for long wear.

Can cleaning products cause asthma?

Yes. HSE lists cleaning products among the main causes of occupational asthma, and cleaning services among the high-risk groups. Some disinfectants are known asthmagens. A product labelled H334 is a respiratory sensitiser, and COSHH then requires exposure to be as low as reasonably practicable. Irritant gases such as chlorine can also trigger attacks.

Do cleaners need COSHH training?

Yes. COSHH requires information, instruction and training for every employee liable to be exposed, cleaners included. Cover the products by name and their risks, where the data sheets are and the assessment findings. Then the precautions: dilution, gloves and eye protection, never mixing, labelled bottles, spills and first aid.

Substances and diseases

Read in any order

GuideSilica dustWhere respirable crystalline silica comes from on site, what it does to the lungs, the exposure limit and the controls. GuideIsocyanatesIsocyanates in 2K paints, foams, coatings and adhesives: asthma risk, controls, RPE and health surveillance. GuideWood dustHardwood, softwood and MDF dust: the exposure limits, why hardwood dust is a carcinogen, and how to control it. GuideCement burns and dermatitisWhy wet cement burns and causes dermatitis, how to prevent it, and what to do when it gets on skin. GuideSolventsSolvents in paints, thinners, adhesives, strippers and cleaners: the health effects, enclosed spaces and controls. GuideDiesel, petrol and exhaustDiesel and petrol as hazardous substances, diesel engine exhaust on site and in workshops, and the controls. GuideLead at workLead paint, roofing and pipework: why the lead regulations apply instead of COSHH, and what they require. GuideOccupational asthmaThe substances that cause asthma at work, how it develops, the legal duties and health surveillance. GuideOccupational dermatitisContact dermatitis at work: wet work, cement, resins and cleaning products, prevention, skin checks and reporting. GuideLegionellaLegionella in water systems: who the duty falls on, the L8 code, temperatures, flushing, testing and records. GuideLegionella risk assessmentWhat a legionella risk assessment covers, who can do it, the written scheme and how often to review it. You are hereCleaning chemicalsBleach, descalers, degreasers and disinfectants: the hazards, products never to mix, dilution and controls. GuideWelding fumeWhy all welding fume is treated as a carcinogen, and the extraction and RPE HSE expects.

Sources

Great Britain law and HSE guidance, read on the dates above. Northern Ireland has its own COSHH Regulations.

Next step

The COSHH register,
tied to the job.

Unibuild keeps each substance’s data sheet and supplier against the jobs, materials and purchase orders that use it, with review dates tracked and every version kept.

Book a demo → See health and safety on Unibuild