Types of hazardous substances under COSHH

When you think of hazardous substances, your mind might jump to chemical factories or industrial plants. But the truth is, hazardous substances can be found in almost every workplace—from offices to construction sites, warehouses, and even schools.

If your business uses, produces, or handles any substance that could cause harm, you must carry out a Control of Substances Hazardous to Health (COSHH) risk assessment.

But what exactly qualifies as a hazardous substance covered by COSHH? Let’s break it down.

What are hazardous substances?

The HSE defines a hazardous substance as “a substance or mixture with the potential to cause harm if they are inhaled, ingested, or come into contact, or are absorbed through the skin.”

Hazardous substances covered by COSHH regulations are:

• Chemicals

• Products that contain chemicals

• Fumes

• Dusts

• Vapours

• Mists

• Nanotechnology

• Gases and asphyxiating gases

• Biological agents

• Germs that can cause diseases

It’s important to note that lead, asbestos or radioactive substances, while they can be hazardous and harmful, they’re not covered under COSHH and have their own regulations you must follow.

Examples of hazardous substances

Now let’s take a look at examples of hazardous substances at work and some of the possible risks to health associated with them.

Chemicals

Chemicals are probably the first thing that comes to mind when you think about a hazardous substance—and for good reason. They can be found everywhere, from industrial plants to offices.  Whether it’s a strong industrial solvent or the cleaning products under the sink in the office kitchen, many chemicals have the potential to cause harm.

Common examples:

• Industrial solvents (turpentine, acetone)

• Acids and alkalis (sulfuric acid, sodium hydroxide)

• Corrosive cleaning agents (bleach, drain cleaner)

The risks to health:

• Skin burns, rashes, and irritation

• Breathing difficulties from inhaling fumes

• Long-term health conditions like organ damage or cancer

Products containing chemicals

Not all hazardous chemicals come in barrels labelled with hazard symbols. Many common products used in everyday tasks contain harmful substances. The risk increases when these products are sprayed, heated, or mixed with other substances.

Common examples:

• Paints, varnishes, and adhesives

• Pesticides and weed killers

• Lubricants and degreasers

• Printer toners and inks

The risks to health:

• Skin irritation from frequent exposure

• Toxic fumes leading to dizziness and headaches

• Fire hazards—many products are flammable

Fumes

Fumes are tiny airborne particles created when a substance is burned or heated. You may not always see them, but they can cause serious harm when inhaled. Workers in welding, manufacturing, and construction are particularly at risk.

Common examples:

• Welding and metalwork fumes

• Plastic-melting or soldering fumes

• Engine exhaust emissions

• Hot tar and asphalt fumes

The risks to health:

• Lung damage and respiratory illnesses

• Neurological issues from heavy metal exposure

• Long-term cancer risks from inhaling toxic particles

Dusts

Dust in the workplace isn’t just about cleanliness—it can be a serious health risk. Fine dust particles can be inhaled deep into the lungs, causing long-term illnesses. Some dusts, like silica for example, can be particularly dangerous.

Common examples:

• Wood dust from carpentry

• Silica dust from cutting bricks, tiles, or concrete

• Flour dust in bakeries

• Textile and cotton dust in manufacturing

The risks to health:

• Occupational asthma and lung disease

• Various lung cancers, nasal cancers and kidney diseases

• Chronic obstructive pulmonary disease (COPD)

• Skin and eye irritation

• Explosive risks—some dusts can ignite under the right conditions

Vapours

Vapours are airborne chemicals released when a liquid evaporates. Many solvent-based substances give off hazardous vapours that employees inhale—often without realising it.

Common examples:

• Paint, varnish, and glue vapours

• Fuel vapours (petrol, diesel)

• Solvent vapours (acetone, benzene)

• Cleaning product fumes

The risks to health:

• Dizziness, headaches, and nausea

• Long-term organ damage

• Fire hazards—many vapours are highly flammable

Mists

Mists form when liquids are sprayed or released under pressure, creating airborne droplets that can be inhaled.

Common examples:

• Spray paint mists

• Oil mists from machinery lubrication

• Chemical mist from cleaning sprays

• Pesticide mists in agriculture

The risks to health:

• Lung damage and breathing problems

• Skin and eye irritation

• Ingestion risks—mist droplets can settle on food or drinks

Nanotechnology

Nanotechnology also known as nanomaterials are incredibly small particles used in high-tech industries. Because they’re so tiny, they can enter the body easily—but their long-term health effects are still unclear.

Common examples:

• Carbon nanotubes (used in electronics)

• Titanium dioxide nanoparticles (in sunscreens and paints)

• Silver nanoparticles (antibacterial coatings)

The risks to health:

• Unknown long-term health effects

• Potential respiratory and organ damage

Gases and asphyxiating gases

Some gases are toxic, some are flammable, and others displace oxygen, leading to suffocation. And a leak in an enclosed space can be deadly.

Common examples:

• Carbon monoxide (from faulty equipment)

• Chlorine gas (used in swimming pools)

• Ammonia (found in refrigeration systems)

• LPG (liquefied petroleum gas)

The risks to health:

• Poisoning and suffocation

• Fire and explosion risks

Biological agents (Germs)

Biological agents include any naturally occurring organisms that can harm human health. While they may not seem dangerous at first, they can cause serious respiratory illnesses, allergic reactions, and infections, if there’s long-term exposure.

Workplaces that are damp, poorly ventilated, or involve water systems, soil, or animal products are at a higher risk of biological hazards.

Common examples:

• Legionella bacteria in water systems (cooling towers, showers, air conditioning)

• Mould spores in damp buildings or poorly ventilated areas

• Fungi and bacteria in agricultural or food production settings

• Animal waste in farming or veterinary work

The risks to health:

• Respiratory illnesses (Legionnaires’ disease from Legionella bacteria)

• Severe allergic reactions from exposure to mould or fungi

• Skin infections from contaminated surfaces or animal waste

Germs that cause diseases

Unlike biological agents that exist in the environment, germs that cause diseases are primarily spread from person to person.

Viruses and bacteria can be transmitted through airborne droplets, contaminated surfaces, or bodily fluids, making them a major risk for any workplace where people are in close contact.

Common examples:

• Bloodborne viruses (HIV, Hepatitis B & C)

• Airborne diseases (Tuberculosis, flu, COVID-19)

• Gastrointestinal infections (Norovirus, Salmonella)

The risks to health:

• Severe illness or long-term health effects

• Serious infections and diseases

Get help controlling hazardous substances in your workplace

By recognising the types of hazardous substances , you can ensure a more comprehensive COSHH risk assessment. Controlling exposure to these risks through elimination, engineering controls, PPE, and training is essential to protecting employee health.

Need a simpler way to manage hazardous substances? Health and safety software can make it faster and easier to complete risk assessments in line with HSE standards, store SDS data, and help you stay compliant—so you can focus on keeping your team safe!

Discover risk management from BrightSafe!