The CheSSE project logo, link to frontpage

Risk Assessment

Assessing risk in the school laboratory and the science classroom.

Table of Contents


In the science classroom, a risk assessment is an analysis of a practical activity for the purpose of identifying any safety hazards associated with the activity, and determining actions which should be taken in order to eliminate, reduce, or control the risk of anyone coming to harm.

This is to make sure that experiments, demonstrations, and handling of chemicals and other lab equipment, can be carried out safely.

Risk management is not about creating a “risk-free” learning environment; it concerns how to facilitate satisfactory risk control. This means recognizing hazards and associated risks and managing these properly, prior to any activity.

A hazard is anything that may cause harm, such as hazardous chemicals, electricity, high temperature, work equipment or a slippery floor.

A risk is the chance of something happening that will have a negative effect on our health or the environment. The level of risk reflects the likelihood and the potential consequences of the unwanted event. 

Hazard, exposure and risk
HAZARD is anything that has the potential to cause harm.EXPOSURE is a necessary condition for a hazard to become a risk.RISK is the probability that hazard will cause harm.

Evaporating dish over Bunsen burner.

A hot evaporating dish and a Bunsen burner have the potential to burn your hand.

Hand close to an evaporating dish over Bunsen burner.

Touching a hot evaporating dish with bare hands, increases the risk for harm.

Hand with glove uses tongs to move an evaporating dish over Bunsen burner.

The likelihood of the hand being burned is reduced with the correct use of tongs.

The potential risk associated with exposure to all types of hazards, not just those associated with the use of hazardous chemicals, must be assessed prior to any activity to protect the health and safety of both students and teachers, and to protect the environment. Precautions must be specified and reviewed each time the activity is carried out to ensure that they are appropriate for the type of activity, the place where it is being carried out, the number and age of students etc.

Types of Hazards

Chemical Hazard

All chemical substances or mixtures that have any kind of labelling according to Classification, Labelling and Packaging of substances and mixtures (CLP) regulations are potential risks. Information regarding chemical hazards and safe handling can be found in safety data sheets (SDS) from chemical manufacturers, from The Classification and Labelling (C&L) Inventory, or from a chemical database.

Even dilute solutions of specific substances can have a risk associated with them in certain concentration ranges. Furthermore, some substances which do not normally carry a warning label may have risk associated with them, depending on how they are used in a particular activity.

Decisions are a matter of balancing the relative risks and benefits, choosing an acceptable level of risk, rather than trying to avoid all risk and all exposure to hazards.

Physical Hazards

Physical hazards are factors or conditions that could cause harm, such as release of compressed gas or steam, hot objects, run-away chemical reactions, noise, sharp objects, surface issues such as a wet floor, slipping or tripping, obstructions, fire, and electricity.

Safety Hazards

Safety hazards include unsafe conditions that may cause harm. Examples of safety hazards are lack of necessary experience or training, hair or clothing getting tangled into equipment, equipment malfunctioning, inappropriate set up or use of equipment, stress, the number of students, an overcrowded room, the age of the students, or behavioural problems.

For example, one student using ammonia solution is not a problem, but a whole class working with ammonia could result in exposure levels becoming dangerously high. Another example, water that is heated to high temperatures, and becomes steam, has the potential to scald the experimenter whereas water at room temperature carries no risk for scalding. Similarly, citrus fruit peel is normally not a source of risk, unless someone in the lab happens to be allergic.

Precautionary Measures

Once the risk has been assessed, necessary precautionary measures should be put in place to reduce the risk from the hazard(s) to an acceptable level.

It is not always possible, necessary, or desirable to eliminate a risk completely. Several other measures can be taken, such as scaling down quantities and concentrations. Ideally, an activity should be modified so that there is no, or a reduced, need for personal protective equipment (PPE) as a control measure. PPE, such as eye protection, gloves, coats or aprons, and safety screens, is considered as the last line of defence in risk assessment.

Regardless of the activity, reduction of risk should be the first control measure you consider. Is there an alternative activity, method, or chemical that is less hazardous that still meets the desired teaching or learning outcomes?

Use of Fume Cupboards

Fume cupboards are used to limit exposure to hazardous or toxic fumes, vapors or dusts. Many chemicals may not require handling in a fume cupboard, especially if they are only being used in very small quantities. In a larger quantity, or with a big group of students, it may be better to recommend that the experiment is carried out in a fume cupboard or fume hood. Sometimes, fume hoods are used instead of fume cupboards. Be aware that these would not give adequate protection in all situations likely to arise in schools. Fume cupboard or fume hood use should be based on a risk assessment of the procedure, and should ideally be in the risk assessment documentation.

Safe Handling of Glassware

Glassware is commonly used in a laboratory. However, glass is fragile and breaks easily. When glass breaks, care should be taken to reduce the risk of cuts. Dispose of the glass appropriately.

Safe Handling of Bunsen Burners

Bunsen burners present fire hazards. They produce an open flame and burn at a high temperature, and the flame is sometimes hard to see. As a result, there is potential for an accident to occur. To reduce the risks, the students need to know how to use a Bunsen burner.

Writing a Risk Assessment

Every task involving the management of risks needs to be subject to a documented risk assessment. The level of detail in the risk assessment should be proportionate to the risk. If different tasks involve the same type of chemical risks, they can be assessed together.

A risk assessment of practical work requires three steps:

  • Identify the hazards associated with the chemicals, equipment and procedures you are planning.
  • Assess the risks connected with each part of the experiment, demonstration or preparation.
  • Decide what precautionary measures should be in place to eliminate the hazard, or to control the risks you have identified.

The risk assessment should be documented, and include:

  • the class, laboratory or classroom concerned
  • all the hazards that you identified
  • the levels of risk associated with these hazards
  • the situations where there is need to eliminate or reduce a risk
  • the measures that should be taken to eliminate the hazard or control the risk
  • which equipment should be available during the experiment or demonstration, or on standby in case of spillage or accident
  • the emergency procedures in case of an accident

Ready-Made Risk Assessments

Ready-made risk assessments or model risk assessments, for example from textbooks, give guidance and could be useful to avoid unnecessary duplication of work. Furthermore, they could provide a quality standard.

However, these should not be adopted without considering how they will be applied in practice. For instance, textbooks and laboratory manuals may include risk assessments of experiments, but it is still necessary to adapt these for your specific circumstances, as every school is different.


Last modified: 

To cite this page, we suggest the following format (APA 7):
Online Resources for Chemical Safety in Science Education. (2022, November 2).
Risk Assessment.