Firstly, note that a COSHH assessment must be carried out by a competent person or persons. This means people who have training and experience in the use of the substance and the process in which it is to be used, and who can competently write an assessment.

But, in order that you may gain understanding of what a COSHH assessment is, we will assume that you and I are the competent persons.

Firstly, we must learn all we can about the substance, its use, and its effects on us and the environment. Our first point of reference is the manufacturer’s material safety data sheet (msds). By law, the manufacturer must supply this on request. It should tell you everything you need to know about the substance and its constituent chemical compounds. To this will be added your knowledge of how and where the substance is to be used.

Firstly, basic information about the substance and its properties.

Identify the substance	What is it?
Is it described as hazardous?	Look for any Hazard symbols e.g.
(If substance and its constituents are not hazardous, it may not need a COSHH assessment)	However, the way it is proposed to use the substance may make it hazardous
What form does the substance take?	Is it a solid, liquid, a gas? Does it arrive as a powder or perhaps as an aerosol? What colour is it?
What are its constituents?	Within the substances may be a few 'nasty' chemical compounds as well as more benign ones. Read the msds carefully
Are there 'workplace exposure limits' given for any of the constituents?	Again get this fron the msd. You may need specialist help to mesure any exposure

Next, its proposed application

How is it applied?	Where does this occur?
Is it spayed on, rubbed on, poured out, mixed, heated, compressed, aerated?	Inside a building? Inside a confined space? Outside in open air?

Next, what effect does the substance have on human beings? (Not forgetting the chemicals that make up the substance.) Consider the ways in which our bodies may come into contact with the substance.

Contact	Effects
If it should get into someone's eyes (eye contact)	The eyes are our most sensitive organs so are always considered separately. Many substances will make the eyes sting, which is a hazard, Some can make you blind.
If someone should swallow it (ingestion)	A very quick route to the body's vital organs- so beware!
If someone should touch it or get it onto their skin (Skin contact)	People often pick things up, but seldom give thought to the effects on their skin. Many substances can cause allergies, just by touching them. And the body can absorb substances through the skin, to suffer internal damage
If it should get into someone's eyes (eye contact)	The eyes are our most sensitive organs so are always considered separately. Many substances will make the eyes sting, which is a hazard, Some can make you blind.

Next, suppose the unthinkable happens and someone is hurt by the substance. What do we do? i.e. First Aid

Consider again each of the ways in which one might come into contact with the substance, and refer again to the material safety data sheet. It should give good advice on what to do if someone were to:

• Breathe it in (inhalation)
• Swallow it (ingestion)
• Touch it (skin contact)
• Get it in his/her eyes (eye contact)

Occasionally, for some classes of hazardous substances, we might have to consider health surveillance for persons working with them. This needs to be recorded on the COSHH assessment.

Next, consider what happens when the substance burns. The msds should give that information too. Fire must be borne in mind when thinking about how and where a substance is to be used.

• Is the substance flammable?
• Will it ignite easily? perhaps just an electric spark would be enough
• When it burns, does it give off toxic fumes or smoke? perhaps special respiratory equipment will be needed when tackling a fire.
• What is the best way to extinguish it when burning?

Next, consider what would happen if a spillage were to occur. This might be the spillage of a small quantity or a very large one. Both might need to be considered, depending on how the substance is planned to be used.

Question	Solution
Will a spillage need to be contained?	Perhaps a spillage mat will be required, or an inflatable bund
What equipment will be used to clear it up?	Brush and shovel? A pump? or soaked up by sand, or earth or sawdust?
What if the spilled substance were to get into drains or watercourses?	Serious consequences of the spillage might cause us to consider moving the process away from drains and watercourses
What personal protective equipment (PPE) might be required?	If needed for day to day use, PPE will probably be needed for clearing up any spillage
How could the spilt material be safely disposed of?	A spilt substance may be contaminated. It may be of no further use, and so may need to be taken away. Check whether the substance is classed as hazardous waste. It may need to be taken away by a special waste contractor
What cleaning of the spillage area would be required afterwards?	Is any residue safe to be washed away with water, or will the area require treatment with a neutralising substance. Again, check the msds

Next, consider the effect on the environment of using the substance.

Question	Solution
How does the substance affet aqueous organisms?	Many substances eventually find their way into rivers and streams, and can harm the lifeforms there
Will the substance break down over a period of time?	i.e is it bio-degradable?
Could the substance be absorbed into peoples' bodies from the environment over a period of time?	Some substances never break down but pass into the soil or air over a period of time, to be eventually taken into our bodies. They can build up there, and do us harm. Such substances should be avoided.

Is there anything else, unique to this substance, that needs to be considered?

No? Then, if this substance is still to be used, the next part of the COSHH assessment process is to put suitable and sufficient control measures in place. The object is to reduce the risks associated with using the hazardous substance to a safe level, by every reasonably practicable means.

There is an hierarchy of control associated with COSHH. It is:-

• Elimination
• Substitution
• Control Protection
• Elimination

We should try to get rid of the need for using the hazardous substance if at all possible. This is the much preferred option. Otherwise, perhaps the hazard associated with the substance can be eliminated. e.g.

• A dust problem associated with a substance could be eliminated by purchasing the material in a pellet form.
• Perhaps a substance could be obtained in liquid form instead of a powder form that perhaps needs to be poured out, weighed, then dissolved.

Perhaps we can obtain a substance in a safer form e.g. a dilute acid instead of a concentrated one. Or Perhaps we can obtain another, safer substance that does the same job.

There are many items that could be classed under the term ‘control measures’: appropriate training for operatives, the provision of information to operatives on the substance and its processes; the provision of competent supervision: all of these need to be considered and specified in the COSHH assessment. These are all ‘controls’ necessary for reducing risks. We can also mean ‘engineering control measures’. A process might be isolated from an operator by enclosing it and using remote, automated controls. The process might be automated completely, eliminating the need for human involvement. Electrical equipment that is ‘intrinsically safe’ might be called for. This might be where an inflammable substance could be otherwise ignited by discharges and sparks form electrical circuits. Finally, we must consider ventilation. If natural, general ventilation is not enough, then we must specify Local Exhaust Ventilation which will extract gasses, vapours and fumes, to take them away somewhere safe.

We are left to consider personal protection, which should always be the last option. If the measures outlined above do not reduce the risks associated with the use of a substance to a safe minimum, then we must consider what personal protective equipment should be provided. This includes such considerations as the wearing of gloves, goggles, overalls, and boots. Respiratory protection, in the form of disposable, half-face or full-face masks with the appropriate filters, may also be required. The ‘competent person’ doing the assessment will need to understand all of these options. And don’t forget that mask filters need to be changed frequently!

All that remains is for the information to be made available to the people affected by it, and to ensure that it is understood. The full COSHH assessment, itemising all the considerations we’ve gone through, must be written out in full, and kept on record.To make the COSHH assessment and its conclusions clearer, consider adding simple coloured sketches to quickly highlight the controls to the reader e.g.

This helps make the COSHH assessment much easier to understand. The COSHH assessment is now complete. But don’t file it away and just forget it! We must put the controls in place. We must also show the COSHH assessment to the people affected by it. And then make sure that it is fully acted upon.

Once use of the substance is underway, we should monitor the effectiveness of the assessment. And, if necessary, revise it. And that is COSHH assessment. But, once again, please note:- A COSHH assessment must be undertaken by a competent person or persons. If you need help, please call on Abbey Health and Safety for assistance.