Substances

Occupational asthma is an allergic reaction that can occur in some people when they are exposed to substances in the workplace.

These substances are called 'respiratory sensitizers' or asthmagens. They can cause a change in people's airways, known as the 'hypersensitive state'.

Not everyone who becomes sensitised goes on to get asthma. But once the lungs become hypersensitive, further exposure to the substance, even at quite low levels, may trigger an attack.

There area wide range of substances encountered in University research laboratories as well as in the Support Services which can cause occupational asthma.

• The Health and Safety Executive has published a list.

Particular care is needed when working with these substances and expert advice should always be obtained.

Further information

Guidance from the Health and Safety Executive on occupational asthma

The University will maintain a comprehensive and up-to-date register of known & suspected asbestos materials, that is accessible to all persons who may need the information, updated as asbestos is removed or discovered, or if its condition changes, in a way which is clear and unambiguous.

Asbestos Policy: Asbestos Policy Statement

Asbestos Register: Asbestos Register

If you have any queries, please contact the Health and Safety Team for advice.

• Biosafety Policy
• Guidance to assist departments develop their own procedures covering the taking of blood specimens
• Guidance on actions following significant laboratory exposure to human body fluids
• Guidance on Hepatitis B vaccination for laboratory workers

Health and Safety Executive Biosafety Links:

• Approved list of biological agents (2021) - the official UK list of micro-organisms according to hazard group
• Compendium of Guidance from the Scientific Advisory Committee on Genetic Modification - guidance on complying with health and safety regulations when working with genetically modified organisms
• HSE information sources on genetically modified organisms - additional guidance supplementing that in the Compendium

The University of Aberdeen is committed to providing a safe and healthy working environment. All reasonable steps will be taken to ensure that all exposure of personnel to substances hazardous to health is prevented or controlled as far is as reasonably practicable and to within statutory limits. COSHH assessments are a vital tool in preventing cases of ill health and injury. It is therefore the policy of the University of Aberdeen that all substances hazardous to health will be COSHH assessed.

COSHH assessments are not to be confused with Risk Assessments, a COSHH assessment is an assessment of the hazards presented by a specific substance.

For more information, please see:

• Control of Substances Hazardous to Health Policy
• Guidance on the safe storage of chemicals

There are also template assessment forms for use. It is up to individuals if they assess chemical and other physical hazards in the same form or separately.

• COSHH Assessment Form
• Risk Assessment Including Chemicals Form
• Risk Assessment Form

Some toxic chemicals and their precursors are controlled by law because they could be used in the manufacture of chemical weapons. The University is obliged to keep records of our use of these chemicals and to make annual returns to the UK Government.

The chemicals which are controlled are listed in three separate Schedules (1, 2 and 3) on the Department of Energy and Climate Change's website.

• Schedule 1 chemicals
• Schedule 2 chemicals
• Schedule 3 chemicals

IMPORTANT

1. You must have agreed with the University Safety Team what record keeping requirements are required before you hold stocks of Schedule 2 and Schedule 3 chemicals
2. You must have obtained a licence from the UK Government before you can hold stocks of chemicals listed Schedule 1.
3. There are restrictions on the import and export of Schedule 2 and 3 chemicals from/to countries which are not party to the Chemical Weapons Convention. These countries are Angola, Egypt, Israel, Myanmar, North Korea, South Sudan, Syria. Contact the University Safety Team before importing or exporting any Schedule 2 or 3 chemicals.

The main hazards associated with cylinders of compressed gas are:

• Those related to the explosive release of energy stored in a cylinder in event of an uncontrolled discharge (cylinders can become jet propelled)
• Those related to the mass of the cylinder (cylinders are tall, thin and heavy; they can inflict damage and injury if they fall over)
• Those related to the properties of the gas stored in the cylinder (e.g. flammable, asphyxiating, toxic, corrosive, oxidant)

To prevent them becoming a source of harm, cylinders should be

1. Stored correctly
2. Moved correctly
3. Used correctly

Storage of cylinders

1. All cylinders not in use (i.e. not connected to equipment) should be stored outside the building in the cylinder store
2. Someone should be appointed as responsible for the cylinder store. He/she should ensure that access to the store is controlled and that it is kept locked when access is not required
3. Cylinders in the store are correctly secured in a vertical position (acetylene and propane in particular should never under any circumstances be placed horizontally either in storage or in use) 4) Cylinders in the store are segregated in accordance with industry guidelines (to help limit the consequences in event of a leak of gas or a fire) stock is rotated so that oldest stock is used first 5) Nothing is kept in the store (other than cylinders).

Movement of cylinders

1. Cylinders must be transported only when secured vertically in a cylinder trolley
2. Within the cylinder store and in the laboratory cylinders should be "milk churned" to get them into position. Cylinders must never be rolled along the ground.
3. Cylinders should not be transported with the pressure regulator attached unless on a trolley specifically designed for this purpose.
4. While moving cylinders out of the store or into position in the laboratory, always keep unsecured vertical cylinders under your direct control - never turn your back on a free standing cylinder. The consequences of it falling over can be severe.
5. Anyone handling gas cylinders should wear protective footwear and industrial gloves
6. If a lift is used to move cylinders between floors, a system must be employed to ensure that a cylinder is never in a lift with a lift passenger. Cylinders must always travel unaccompanied in lifts. A leak in any type of cylinder could cause the air in a lift car to become unbreathable. If this were to happen while a lift was stuck between floors, the consequences could be fatal. Anyone who has seen the bursting disc of a carbon dioxide cylinder fail (and it can happen without warning) will know how rapidly carbon dioxide can flood out of a cylinder and would not want to have been in a confined space with the cylinder with no immediate means of escape.

Use of cylinders

1. All cylinders in a laboratory must be mounted vertically on a stand or secured to the bench or to the wall. Acetylene and propane must never be used or stored in a horizontal position.
2. Cylinders should be fitted with a regulator valve of the correct type (e.g. it is not safe to fit a nitrogen regulator to an oxygen cylinder). The cylinder key should be secured to the gauge so it is always available to enable an emergency cut off.
3. Regulators should be replaced every five years (from date of manufacture) regardless of the amount of use they have received
4. Do not use excessive force on valves and gauges. If a cylinder valve cannot be opened readily, it should be returned to the supplier.
5. Never use oil or grease on any part of a valve or regulator. Do not use PTFE tape on any part of a compressed gas system. If a gas tight seal cannot be obtained, change the fittings.
6. Always open valves slowly. Rapid opening may result in an explosion.
7. Check your equipment regularly for leaks. Always use the proprietary liquids which are intended for detecting leaks. (Do not get into the habit of using soap and water. Some soaps contain fats which react violently with oxygen.)
8. Regulator valves are not intended for use with low flow rates and low back pressures. Always use a needle valve to control gas flow from the low pressure side. These can be obtained from "BOC" as FINE CONTROL VALVES, the thread depending on the gas to be controlled.
9. All connections should be secure; a "jubilee" clip is ideal. A safety valve of some form is advisable to prevent high pressure being applied to your apparatus.
10. Gas supplies feeding a source of ignition (e.g. a welding or glass working torch) must be fitted with non-return valves or explosion preventers.
11. After use, always shut off the gas at the cylinder valve, and release the pressure in the gauges before finally shutting all valves. Do not rely on the regulator to stop the gas flow for more than brief periods.
12. Understand the hazardous properties of the compressed gases you are using (e.g. flammability, toxicity).

The hazards arising from the use of low temperature liquefied gases (cryogenic fluids) are:

• Asphyxiation from oxygen deficient atmospheres (This is a problem particularly in poorly ventilated areas);
• Cold burns from the intense cold (The damage to the skin is similar to that caused by heat burns. The eyes are particularly vulnerable to damage.);
• Over-pressurisation from the large volume expansion ratio from liquid to gas on evaporation.;
• Explosion of vials stored in liquid nitrogen if the cap on the vial leaks - see guidance
• Fire in oxygen enriched atmospheres (While obviously a problem with liquid oxygen, it can also be a problem with liquid helium and sometimes with liquid nitrogen. Near the surface of the cryogenic fluid is possible for oxygen to be condensed from the atmosphere causing localised oxygen enrichment.);
• The effects of very low temperatures on materials, (For example, normally ductile materials can become brittle and methods of jointing need careful consideration because of possible differential rates of contraction.)

Asphyxiation hazards

The ratio of volume of gas to volume of liquid for low temperature liquefied gases can be relatively high. At 15^oC and 101.3 kPa the ratios are:
Nitrogen 682
Helium 738
Argon 822

Thus 1 litre of liquid nitrogen will produce 682 litres of gas. Air normally contains 20.9% oxygen. If liquid nitrogen is spilled in a room it is possible for an oxygen deficient atmosphere to be produced which can be hazardous to anyone in the room. Oxygen deficiency initially leads to loss of mental alertness and distortion of judgement and performance. This happens within a relatively short time, without the person's knowledge and without prior warning.

It is important therefore that cryogenic fluids which could give rise to oxygen deficient atmospheres are stored and used in adequately ventilated rooms. In determining whether ventilation is adequate consideration should be given to:

• Normal evaporation of the cryogenic fluids in the room;
• Filling losses from filling vessels from a warm condition;
• Spillage of the contents of the largest container in the room or boiling off due to failures such as loss of vacuum insulation or rupture of a bursting disc.
• The following simple calculation can be used to establish a threshold for the amount of liquid nitrogen held in a room beneath which it is unlikely to be necessary to investigate further the possibility of an oxygen deficient atmosphere developing:
  • 1 litre of liquid nitrogen can produce up to approximately 700 litres of nitrogen gas. As a rule of thumb, a spillage or instantaneous release of 1/7^th litre of liquid nitrogen per cubic metre of room volume, even in an unventilated room, may be dismissed as it will reduce the oxygen content by only 2%.
  • Above this threshold more detailed scrutiny will needed and the adequacy and reliability of the ventilation in the room assessed. Ventilation should prevent oxygen content falling below 18%. If ventilation is not adequate consideration should be given to the use of oxygen monitors. (It should also be remembered that cold nitrogen gas will be heavier than air and may accumulate at a low level.)
  • Even if a room is adequately ventilated, consideration should be given to the possibility of a failure of the ventilation system and whether those working in the room would be aware of the failure. Installation of alarms to indicate failure of ventilation or, in some circumstances, installation of oxygen monitors might be necessary.

Use of cryogenic fluids

1. No one should work with cryogenic fluids until they have been thoroughly instructed and trained in the nature of the hazards and the precautions to be taken. The hazards associated with cryogenic fluids will not be readily apparent to someone who has not received appropriate training.
2. If contact with the cryogenic fluid is possible, goggles (or preferably a full face visor) must be worn.
   • Other protective clothing should be worn depending on the risk associated with the work.
   • Clothing should be non-absorbent and not have features which could trap a spillage of fluid (e.g. open pockets, turn-ups on trousers).
   • Trousers should be worn outside boots.
   • Watches and jewellery which could trap cryogenic fluid close to the skin should not be worn.  If gloves are worn they should ideally by "Cryo-gloves". (These are gloves which are specially designed for low temperature work. If other gloves are used they should be non-absorbent leather gloves and they should be a loose fit so they can easily be removed if fluid should splash into them.
   • Sleeves should cover the ends of the gloves.
   • Gauntlet gloves should not be used as they increase the likelihood of a spillage going into the glove.
   • Those working with cryogenic fluids must be aware of the first aid treatment for cold burns
3. Cryogenic fluids should be dispensed only into vessels of a type which have been designed for use with the particular fluids concerned. The vessels must have vented lids (unless they are of the self-pressurised type in which case they should be fitted with safety relief valves). The lid on a vessel should be secured down only if the securing method is integral to the manufacturer's design of the lid and permits the vessel to vent even when the lid is secured in place. Vessels should be clearly labelled to identify the cryogenic fluid which they contain.
4. When using liquid oxygen it is vital to ensure that equipment is scrupulously clean as dirt, oil or grease can pose a serious fire or explosion hazard. Any jointing materials must also be oxygen compatible. When using other cryogenic fluids it is good practice to use oxygen compatible materials in these cases as well.
5. Materials used in experiments involving cryogenic fluids must be chosen with care. The most significant considerations are that of brittle fracture and ensuring that joints are suitable for the temperatures which will be established.

Storage of bulk stocks of cryogenic fluids

1. Someone should be responsible for ensuring that

• the storage areas are maintained in a satisfactory condition
• adequate ventilation is provided
• if necessary, oxygen monitors are installed and maintained according to manufacturer's recommendations
• necessary personal protective equipment is available
• appropriate warning notices are posted
• containers used for storage are suitable for purpose and are maintained in good condition

2. A face visor and appropriate gloves must be worn when dispensing from or otherwise handling bulk stocks.

3. If an oxygen monitor is fitted there should be arrangements for its operation which should include a prohibition on entering the area if the alarm has activated and a requirement to leave the area immediately if the alarm should activate. Staff must receive training so they know the action to take should the alarm activate.

Transport of cryogenic fluids

Cryogenic fluids must never be transported in lifts accompanied by people, they must always travel unaccompanied. A lift cage is a confined space: if the lift were to become trapped between floors for a period it is possible that rapid evaporation of the fluid due to failure of the container could cause the air to become unbreathable.

Fume cupboards are intended to keep harmful substances away from the person using fume cupboard and away from other users of the laboratory. The cupboard will do this effectively only if:

1. It is used in the correct manner and
2. It is regularly maintained

Use of a fume cupboard

1. Fume cupboards should be used only for experimental work and not as storage areas. Use for storage will interfere with the air flow within the cupboard and will increase the likelihood of harmful substances being released from the cupboard into the laboratory. If there were to be an accident, the presence of stored chemicals in the cupboard would increase the risks. No one should carry out an experiment in a fume cupboard that is being used as a store.
2. Do not set up equipment close to the front edge of the fume cupboard. This will increase the likelihood of turbulent flow in the air stream being drawn in at the front of the cupboard. Turbulent flow can result in "eddies" in the air stream with a consequently greater risk of harmful substances being released into the laboratory. As general guide, equipment should be set back at least 150mm from the plane of the sash. Equipment should not be put so far back that it obstructs the extract slot at the bottom of the back of the cupboard (or so far back that the operator has to put his/her head in the fume cupboard to operate the equipment!).
3. Avoid unnecessary clutter. Large objects such as safety screens, ovens, trays etc will all cause turbulence in the air being drawn across the base of the cupboard. The effect can be minimised by raising all large objects about 50mm above the base of the cupboard with blocks.
4. Avoid rapid movements in front of and within the fume cupboard. Any sudden movement is liable to disturb the air flow and allow harmful substances to escape
5. Fume cupboards are not designed for work with micro-organisms. Microbiological safety cabinets must be used for work with hazardous micro-organisms.

Maintenance of fume cupboards

The best designed and engineered installation will cease to perform effectively if not maintained on a regular basis. It is a legal requirement that all fume cupboards are maintained and that their performance is measured at least every 14 months. Inspection and maintenance is carried out in accordance with the relevant British Standard.

1. Someone should be responsible for ensuring that

• fume cupboards in the School are inspected and maintained
• records are kept of inspection and maintenance and certificates provided by maintenance contractors are kept on file
• face velocities are marked on the cupboards. (Face velocity is the speed at which air is drawn in through the front of the fume cupboard.)
• any fume cupboard which is not inspected on schedule or which fails its inspection is taken out of use.

2. Every 12 months contractors arranged by Estates will

• check the condition of services to the fume cupboard and the functioning of any alarms and controls
• carry out a face velocity test and record the face velocity and the date of measurement on a label on the outside of the fume cupboard.
• carry out a detailed check on the condition of the fan
• check the stability and condition of the discharge stack
• check and clean duct work as is necessary
• check that the make up air into the laboratory is satisfactory
• provide a certificate of inspection

Highly flammable liquids (HFLs) should be treated carefully so

• They do not become a source of fire
• They do not fuel an existing fire

A HFL is a liquid with a flash point below 32 deg C (The flash point of a liquid is the lowest temperature at which the liquid gives off vapour in sufficient concentration to form a combustible mixture with air near the surface of the liquid.) The flash points of some common laboratory solvents are:

• ethanol +12 deg C
• toluene +4 deg C
• acetone-19 deg C
• carbon disulphide -30 deg C
• diethyl ether -45 deg C

As the flash points of all these liquids are below room temperature the liquids will always constitute a major fire and explosion hazard. The last three liquids have flash points below the temperatures which may be found in a refrigerator or freezer and will therefore constitute an explosion hazard even when in cold storage.

Bulk stocks

1. Bulk stocks of HFLs must be kept in the solvent store
2. Entry to the store should be restricted to authorised keyholders
3. Bottles of HFLs should be issued only to people with sealed bottle carriers capable of containing the contents of the bottle in event of spillage. The bottle carriers must be used to transport the HFLs to the laboratory.

Laboratory stocks

1. The total volume of HFLs in any laboratory or room in the department (other than the designated bulk solvent store) must be kept as low as possible and under no circumstances must it exceed 50 litres. (The 50 litre limit is set by legislation.)
2. All HFLs in a laboratory must be stored in specially designed and approved fire resisting cabinets.(Ordinary metal storage cabinets are not acceptable.) Cabinets should be located away from exits from the laboratory. Cabinets must be conspicuously marked with the approved labels to indicate that they contain HFLs. Cabinets should be used only for solvents and never for oxidants, acids, alkalis or other materials which could react with the solvents or cause corrosion of the cabinets. HFLs should not be stored on the open bench or in fume cupboards.
3. Bottles of HFLs temporarily removed from their storage cabinets should not be left on the open bench in direct sunlight. (Even in Aberdeen during the winter a relatively short period in sunlight can be enough to break a bottle through the build up of pressure caused by the heating effect of the sunlight.)

Refrigerator storage

1. If it is necessary to place HFLs in a refrigerator or freezer it is essential that a special refrigerator / freezer is used. It must be spark proofed and protected against an explosion. Even a very small amount of HFL in an ordinary refrigerator or freezer can create an explosive atmosphere which can then be ignited by a very low energy spark (e.g. from a thermostat). The consequences can be devastating. It is very likely that the resulting explosion will, at the very least, completely destroy the laboratory containing the refrigerator or freezer. Even in a protected refrigerator the HFLs must be kept in closed containers impervious to the solvent concerned. (Many plastics are not suitable.)
2. All refrigerators, freezers and cold rooms which are not spark proofed must be labelled with a sign indicating that they are not suitable for storage of any HFL (in either open or closed containers). Even if the flash point of the liquid is above that of the working temperature inside the refrigerator, storage is still not permitted. If the cooling system were to fail, the temperature could rise above the flash point and an explosive atmosphere could result.

Empty bottles

Empty bottles which once contained HFLs should be handled and stored as carefully as full bottles as they may contain explosive vapours.

Work with Highly Flammable Liquids

1. Those working with HFLs must be aware of the flash points of the liquids and must take care to exclude ignition sources from the work area. The risk assessment for the work must address how this will be done.
2. In deciding what might be a possible source of ignition, note must be taken of the autoignition temperature of the HFL. (The autoignition temperature is the minimum temperature required to initiate combustion.) It is not only sparks and naked flames which can be a source of ignition. If the vapour of the HFL comes into contact with a surface at a temperature in excess of the autoignition temperature, the vapour can ignite. The autoignition temperatures of two common solvents are:

• carbon disulphide 100 deg C
• diethyl ether 160 deg C
• Carbon disulphide vapour can ignite if it comes into contact with pipes carrying super-heated steam. The temperature of the element of a heating mantle or the surface of a hot plate will be higher than the autoignition temperature of diethyl ether.

Further information

Guidance on the operation of solvent stores

• Guidance note on the transport of dangerous goods by road in University vehicles
• Guidance on the packaging of infectious material for shipment
• Guidance on the packaging of Activity Class 1 Genetically Modified Microorganisms

Visit the University's dedicated Waste web pages .