Internal User

Academic staff and technicians of the teaching and research laboratories are responsible to keep their electric equipment safe and to arrange for regular thorough checks on their electrical equipment. They should often inspect earth connections, plugs, and cables for loose connections and faults. The plugs used in the laboratory should comply with British Standard 1363 or 546. All high voltage instruments must be well connected to the dead earth.

Detailed regulations: see the Safety Booklet.

The dangerous or toxic substances, like As, Hg, Ga, K, Na, Pb, T1, etc., used in teaching and research laboratories/section must be stored in lockable cabinets. The key must be under control of the Supervisor of laboratory/section. The Supervisor must ensure that the staff and students under his/her supervision clearly understand and follow the safety rules and emergency procedures. All measures for safety and emergency actions must be regularly checked.

Academic staff and technicians are responsible for the safety of using compressed gas in their laboratory. In case of fire, the staff and Fire Warden should report to the FSD Fire Officer the location of the gas cylinders and the kind of gas contained in the cylinders.

Compressed gas cylinders used in the laboratories contain a tremendous amount of energy, which can be violently released under certain conditions. The flammable and/or toxic nature of some of the gases could pose a serious potential hazard if accidentally released. Compliance with the following guidelines can greatly reduce these risks.

• Each cylinder must bear a label identifying its contents. Make sure you know the contents and characteristics of the gas before use.
• Use gases in areas having adequate ventilation.
• Cylinders should be moved only with a suitable trolley, never rolled or dragged.
• Cylinders must not be transported with the regulator attached.
• In the laboratory cylinders must be strapped to the wall, bench top or other firm support. Cylinders should not be subjected to temperature over 50 ^oC or a direct flame.
• Cylinders containing oxygen should be kept away from flammable gases or large quantities of flammable liquids.
• Use proper tools to tighten the regulator and to open the cylinder main valve.
• Check leakage of all joints after the completion of the connection, using soapy water.
• Never tamper with safety devices in cylinder, regulator or valve. The cylinder main valve should be shut off when it is not in use.
• If the gas is corrosive, the cylinder main valve shall be worked frequently to prevent it from corroding and sticking. Regulator and valves shall be removed and flushed with dry air or nitrogen after use, not just left on the cylinder.
• The date required for pressure test of the cylinder shall be noted for all privately owned cylinders as they are required by law to be pressure tested at regular intervals.

For vacuum systems, every operator should carefully read the manufacturer's guidance and instructions or consult his/her supervisor before operating the vacuum system.

The primary hazard from laser radiation is exposure of the eye and to a lesser extent, the skin (particularly with a high power UV laser). As lasers are widely used for a variety of purposes in our teaching and research, great precaution is taken for the laser safety.

The Departmental Radiation Safety Representative should register all laser equipment in the department and all persons using the laser equipment. Caution warning labels and tags should be placed prominently on the laser housing and control panel. Measures to minimise laser hazards include:

• Classes III and IV lasers should be used in a designated laser area, conspicuous signs and warning light indicating that laser is in operation and that it could be dangerous should be prominently placed both inside and outside the work area, and on doors providing access to the area. Doors should be locked during laser' usage.
• Only authorized persons can operate the laser equipment and the laser should not be left running unattended.
• Always work with the maximum room lighting (minimum pupil).
• Remove watches, rings, bracelets and other shiny jewellery while working in the designated area.
• Never look directly along a laser beam or at reflections caused by a laser.
• Safety eyewear designed to filter out the specified laser should be worn whenever risk of exposure to hazardous levels exists.
• Good housekeeping practices should be used to ensure that no specular objects are discarded in the laser beam path.
• All electrical connections should be adequate with proper earthing.
• Always report any accidental exposure as soon as possible.

See the Code of Practice: 'Protection Against Laser Radiation in Laboratory'.

Cryogenic gases could result in a deep freeze, and could produce excessive pressures when stored in a closed container. It could expand quickly if heated. Precautions should be taken when handling cryogenic gases. To safely use cryogenic gases, one should:

• Avoid contact with both the liquid and the gases as they can cause frostbite. Do not touch uninsulated piping.
• Wear loose-fitting thermal gloves, goggles and/or face shield and closed shoes.
• Work in a well ventilated area. Liquefied gas vaporizes and expands rapidly, e.g. nitrogen expands almost 700-fold.
• Never attempt to prevent vapours from escaping from cylinders of liquefied, cryogenic gases. Since they are not in thermal equilibrium, vapour is produced as the liquid boils and, if not vented to the atmosphere, could produce excessive pressure.
• Use only the special (usually metal) tubing designed for use with these gases. Do not improvise with plastic or rubber tubing.
• Be aware that oxygen enrichment and a fire hazard can result from the condensation of oxygen (boiling point -183 ^oC) from the air onto piping cooled by liquid nitrogen (boiling point -196 ^oC).
• If a glass dewar flask is used as container of small quantities of liquid nitrogen, the exposed glass part of the flask should be taped to minimize the flying glass hazards in case of implosion or explosion.
• If a domestic thermos flask is used as container of small quantities of liquid nitrogen, the integrity of the plastic sealing ring of the thermos should be checked regularly to ensure that no liquid nitrogen can get into the space between the thermos and the outside container. In every case ensure holes are drilled in the base plate to allow gas to escape.
• Avoid contact with the liquid nitrogen directly. Always wear gloves (leather or CRYO-GLOVES) when handling anything that is in contact with liquid nitrogen.
• Protect your eyes with safety spectacles with side shields, safety goggles or face shield. Eyes can be damaged even by the cold gas issuing from liquid nitrogen.
• When charging a warm container or when inserting objects into the liquid, perform the operation slowly to minimize boiling and splashing.
• If skin contacts liquefied cryogenic gases, thaw burned area slowly in cold water. Do not rub.

Responsibilities
Academic staff, student supervisors, and laboratory technicians are responsible for establishing safe procedures and providing the protective equipment needed in handling chemicals. They must instruct their personnel about potential hazards, safety precautions, waste handling, the consequences of an accident, and the actions to take in case of an accident. It is also their responsibility to ensure all chemicals are labelled adequately.

Chemical storage
Bulk quantities of dangerous goods (DG) should be and are stored in Central D.G. Stores managed by the University Safety Office.

General requirements for keeping small quantities of chemicals in laboratories are as follows:

• Provide fresh air ventilation.
• Clearly label the storage area and each container. Container labels must give the chemical name, type of hazard, special precautions, and emergency information where space permits. Labels are available from the Safety Office.
• Store heavier items on lower shelves.
• Chemicals, particularly those known to decompose with time, should also be marked with the date of receipt.
• Carcinogens and highly toxic chemicals should be stored in double containment.
• Separate incompatible chemicals by physical barriers. For example, the following classes of chemicals are mutually incompatible: acids, bases, oxidizers, pyrophoric, flammables, toxic, and water reactive.
• Provide a means to contain spills (e.g. trays).
• Limit quantities and observe shelf-life limits.
• Only flameproof refrigerators or those where all electrical contacts (thermostats, lights etc.) are moved externally are suitable for storage of flammable liquids. The storage of volatile, flammable liquids in ordinary refrigerators can lead to and has led to serious explosions.

Handling solid and liquid chemicals

• Keep the work area clean and orderly.
• Do not eat, drink, smoke, apply cosmetics, or store food in the work area. Read all container labels and, if necessary, the MSDS'S.
• Use required safety equipment. The minimum protective clothing is a laboratory coat and safety glasses; for additional protection, wear gloves and a face shield.
• All works should be carried out in an efficient fume cupboard or at least in well ventilated rooms.
• Wipe off splashes on the skin first by a dry cloth, then immediately with plenty of cold water followed by washing with hot water and soap. Never use organic solvents because of the risk of adsorption.
• Thoroughly rinse eyes affected by chemicals with water and immediately afterward take the patients to a medical centre. Inform medical personnel of the chemical involved.
• Immediately remove any items of clothing soaked with corrosive substances.
• Wash your hands regularly when working with chemicals, especially before you leave the laboratory.
• Breakable vessels must not be carried by the neck and must be supported from below. They must be transported in baskets or carrying frames over longer distances such as up and down stairs, or along corridors. 

Flammability hazards
There is a high fire risk in many laboratories because of the storage and handling of flammable liquids. It is, therefore, essential that the means of escape from the workplace are not obstructed.

The following precautions should be observed:

• Do not use an open flame to heat a flammable liquid.
• Use an open flame only when necessary and extinguish it when it is no longer actually needed.
• Before lighting a flame, remove all flammable substances from the immediate area. Check all containers of flammable materials in the are to ensure that they are tightly closed. Tell your colleagues that you intend to use naked flames.
• Quantities of flammable substances in laboratories should be kept to a minimum. The maximum storage is 20 L of any one substance but not more than 40 L in aggregate. When not in use solvents should be kept in suitable fire resistant cabinets.
• Empty containers which have held flammable materials will contain explosive quantities of vapour if the container is not washed out or ventilated.

Highly reactive chemicals and unstable chemicals 
Some chemicals react in combinations with others at ordinary temperatures, sometimes with great violence. This reactivity may be manifested as a corrosive effect, or as the liberation of a large amount of heat or even an explosion when the chemical comes into contact with others or is exposed to moisture or air. For example:

1. Powerful oxidising agents such as perchloric acid, nitric acid or chlorine react violently with easily oxidisable materials such as hydrocarbons.
2. Metal alkyls such as triethylaluminium burst into flames on exposure to air.
3. The alkali metals react vigorously with water.

Although not themselves explosive, some compounds can cause their containers to burst because of the high pressure of gas generated in them through, e.g. hydrolysis, or decomposition, chlorides of aluminium, titanium and silicon, formic acid.

Some chemicals can explode if heated or subjected to mechanical shock, like metal acetylides, azides, azo and diazo compounds, chlorates and perchlorates, highly nitrated organic compounds, nitrogen halides, organic peroxides, and organic salts of per-acids.

Peroxidisable chemicals, when in the presence of oxygen and stored for long periods of time, or when exposed to sunlight, can form unstable peroxides. These peroxides may explode if the container is shaken or heated. Examples of peroxidizable materials are diethyl ether, tetrahydrofuran, dioxan, alkali metals, olefins, and vinyl monomers. The precautions are:

• Stored in dark containers away from direct sunlight; in a storage cabinet for flammable liquids.
• The date of opening should be marked on the bottle.
• Chemicals should be tested for the presence of peroxide regularly and always prior to use.

Some chemicals which have explosive properties when dry need to be kept wet or moist for safe storage: e.g.

Dinitrophenols
2,4-Dinitrophenylhydrazine
4-Fluoro-3-nitrophenylhydrazine Hexanitrodiphenylamine Picric acid
Picryl chloride
2,4,6-Trinitrobenzenesulphonic acid

For these chemicals, the following safety procedures should be taken:

• Inspect containers regularly and add water as necessary.
• When the contents have gone completely dry, immerse the container in water, with a small amount of detergent, for at least 24 hours.
• With the container still under water, slowly unscrew the cover, allowing water to wet the screw threads.
• Once the closure is loose, remove the container from the water bath, remove the cover and add the required amount of water. 

Emergency response for chemical spill
Small spills can usually be cleaned up safely by the employees involved. Employees must be trained to handle cleanup of small spills. Material for clean up of common chemical spills are available from the Safety Office. Keep used material in a waste container.

If a spill involving large amounts of hazardous chemicals occurs:

1. Alert your fellow workers immediately.
2. Confine spill if safe to do so.
3. Open the windows and switch on the fume cupboard to ventilate the area.
   
   • turn off all burners;
   • switch off all electrical equipment which have hot surfaces, (e.g. hot plate) or/and generate electric spark (e.g. brush type motor) NOT in vincity to the spill and
   • do NOT switch on/off or unplug any electrical equipment.
4. Call nearby Fire Brigade, Security Guard and Safety Office.
5. If your clothes are contaminated, remove them immediately.
6. Evacuate the room. Make sure no body stays behind. Close the door(s) of the laboratory after you leave.
7. Keep distances from the laboratory but with the entrance in sight, forbid unauthorized entry to the laboratory and wait for the arrival of the fire brigade.

The arrangement of chemical waste 
See the code of practice: 'The Arrangement of Chemical Waste'.

See the Code of Practice: 'Guidelines For Chemical Safety In Laboratory', and 'Guidelines For Chemical Labelling'.

See the regulations issued by the Labour Department: 'Handbook on Guarding and Operation of Machinery'.

Responsibilities
It is required by law that any person working in controlled/supervised radiation areas or working with irradiating apparatus in University premises be designated either as a radiation user or radiation worker. A radiation user/worker has the responsibility of ensuring that radiation exposure to all persons, including oneself, is kept as low as reasonably achievable and in any case below the stipulated dose limits.

All radioactive substances and irradiating apparatus in the department should be registered by the Departmental Radiation Safety Representative. The Departmental Radiation Safety Representative will regularly inspect the controlled/supervised radiation areas and arrange for appropriate protective measures to be implemented.

Laboratory monitoring
Each controlled area is required to install and operate an appropriate radiation monitor for the work performed therein. Additionally, air-sampling and surface monitoring will be carried out by staff of the Safety Office.

Radiation work and pregnancy
The radiation dose limits prescribed for designated radiation workers are not applicable during pregnancy, particularly during the early stages.

Therefore, radiation users/workers who know or suspect that they have become pregnant, must report immediately to a doctor in the University Health Clinic so that advice may be given and the necessary action taken.

Use of thermoluminescent dosemeter (TLD)
The TLD must be worn when working inside controlled/supervised radiation areas. The dosemeter should be worn on that part of the body expected to be exposed to the highest radiation dose. For certain purposes, supplementary wrist or finger dosemeters may be required. When not in use for monitoring purposes, the TLD should not be left inside the controlled/supervised radiation areas unattended.

Radioisotope shipment
An outline of recommended procedures to be followed when receiving packages of radioactive materials.

1. It is recommended that, as a matter of routine, rubber or plastic gloves be worn whilst processing the package.
2. Monitor the outside of the package to determine the radiation field (hard betas/gammas) or possible contamination (soft betas).
3. Install suitable shielding around the package (hard betas/gammas).
4. Check for possible breakages or cracks in the vial; perform wipe tests as necessary.
5. Record nuclide, chemical composition, activity and date of receipt in register. Ensure container is properly labelled.
6. If material is not to be used immediately, place in safety container and store in a shielded safe or refrigerator as appropriate.

Radioactive waste disposal
All radioactive wastes should be collected in approved and labelled containers. A waste collection service is available from the Safety Office. It is the responsibility of the user to keep proper records of the nature and content of the waste material in each container and to inform the Safety Office when collection is required. Appropriate forms may be obtained through the web (http://www.hku.hk/local/radioiso/rpframe.htm). Radioactive waste MUST NOT be discharged into sewers or normal rubbish bins.

Procedures to minimise radiation hazards
Initial design of experiment

1. All operations should be planned to limit the spread or dispersal of radioactive material. To this end all unnecessary movement of persons or materials should be avoided.
2. Planning should allow adequate time for the operations required.
3. The use of new techniques should first be tried out with inactive materials or with material of low activity before being put into operation.
4. Areas in which radioactive work is carried out should be designated, marked and monitored. At the boundaries of such areas, monitoring and control measures should be set up if so required by the levels present.
5. Equipment, glassware, tools and cleaning equipment for use in any particular active area should not be used for work in inactive areas and should be suitably marked. Special consideration should be given to avoiding contamination of major items of equipment which might need to be transferred for economic reasons.
6. When a choice between several isotopes of varying toxicities is possible, one of relatively low toxicity should be used.
7. Materials of low specific activity should be used if possible.
8. The quantity of radioactive substances chosen as necessary for a specific purpose should always be as small as possible.
9. The working methods should be studied and procedures adopted to avoid as far as possible the dispersal of radioactive material, in particular through the formation of aerosols, gases, vapours or dusts.

Working procedures (general)

Laboratory rules must be observed absolutely and these will normally include an appropriate selection from the following:

1. The following should not be introduced or used in working places containing unsealed sources:
   
   • Food or beverages.
   • Smoking items or snuff tobacco.
   • Handbags.
   • Lipsticks and other cosmetics, or items used to apply them.
   • Utensils for eating or drinking.
2. Hands should be washed thoroughly before leaving the controlled area (special attention should be given to the nails, in between fingers and outer edges of the hands).
3. Monitoring of hands, shoes and street clothing, if worn at work, may also be necessary before leaving the controlled areas.
4. No sealed or unsealed radioactive sources should be manipulated with the hands.
5. All radioactive sources should be handled with equipment and facilities providing protection against external radiation to compile with the following limits:
   
   • inside controlled areas: less than 0.01 mSv/h
   • inside supervised areas: less than 0.003 mSv/h
   • in general public areas: less than 0.0001 mSv/h
6. Manipulations should be carried out over a suitable drip tray, or with some form of double container which will minimize the importance of breakages or spills. It is also useful to cover the working surfaces with absorbent material to soak up minor spills. The absorbent material should be changed when unsuitable for further work and be treated as radioactive waste. The handling tools and equipment used should be placed in nonporous trays with absorbent disposable paper, which should be changed frequently. Pipettes, stirring rods and similar equipment should never be placed directly on the bench or table. After use, all vessels and tools should be set aside for special attention when cleaning.
7. No solution should be pipetted by mouth in any isotope laboratory.
8. Anyone who has an open skin wound below the wrist (protected by a bandage or not) should not work with radioactive isotopes without medical approval.
9. The use of containers, glassware, etc., with cutting edges should be avoided.
10. Glass-blowing by mouth should be avoided in places where unsealed radioactive substances are utilized.
11. Only self-adhesive labels should be used in controlled areas. Labels that must be wetted should be avoided.
12. Protective clothing appropriate to the radioactive contamination risks should be worn by every person in the controlled area, even if only very small quantities of radioactive materials are manipulated.
13. Rubber gloves should be worn when working with unsealed radioactive substances. Rubber gloves are provided to protect against contamination of the skin and are of no value for protection from penetrating radiation.
14. Care should be taken to avoid needless contamination of objects by handling them with protective gloves, in particular light switches, taps, door knobs, etc. The gloves should be either taken off or a piece of non-contaminated material (paper), which should be disposed of afterwards with the contaminated residue, should be interposed.
15. Contaminated gloves should be washed before taking them off.
16. A method of putting on and removing rubber gloves without contaminating the inside of the gloves should be used. This procedure is such that the inside of the glove is not touched by the outside, nor is any part of the outside allowed to come in contact with the bare skin. It is desirable to use gloves for which the inside and outside are distinguishable.
17. Radioactive contamination of the air of the working places should be reduced as much as possible. All operations likely to produce radioactive contamination of the air through the production of aerosols (in particular the heating of radioactive solutions), smoke or vapours should be done in an air-tight enclosure kept below atmospheric pressure (glove box) or in a fume hood.
18. Wet operations should be used in preference to dry ones.
19. Frequent transfers should be avoided.
20. Clean up spills immediately to prevent contamination of the atmosphere through dusting.
    
    For work with animals one must also pay attention to:
    
    
21. Excrete, body constituents from biopsies and autopsies and animal cadavers should be treated as radioactive wastes. Possible hazards of spread of contamination through the decomposition process should be prevented, e.g. by deep freezing, use of disinfectants, sealed plastic containers, etc.
22. Special provisions for the collection of excreta and decontamination of cages should be made.
23. The radioactive animals or their cages should be marked with labels indicating the nature and amount of radioisotopes used and the time of administration.
24. No uncontrolled exchange of animals, instruments, cages, etc., between active and inactive laboratories should be allowed.
25. Precautions should be taken to prevent the possibility of contaminated wounds in the course of handling the animals and of contamination from radioactive aerosols or splashings produced by animal's movements, coughing, etc.
26. The presence of vermin as potential vectors of contamination should be considered.

Storage

1. All radioactive sources must be clearly labelled giving information on activity, date and chemical form.
2. The place of storage should be adequately shielded.
3. Only authorized personnel should be allowed to introduce or remove sources into or from the place of storage, which should be secure against tampering.
4. The place of storage should be chosen so as to minimize risk from fire.
5. The places where sources are stored should be inspected regularly and checked for possible contamination.
6. When either sealed or unsealed sources are liable to release a radioactive gas, their place of storage should be efficiently vented to the open air by mechanical means before it is opened.
7. Records should be kept of all stored radioactive sources.
8. Bottles containing radioactive liquids should be placed in vessels large enough to hold the entire contents of the bottles in case of breakage.
9. Special precautions are required when opening vessels containing radioactive liquids liable to catch fire, explode or froth.

Accidents
Any unplanned happening which may introduce a radiation hazard is considered to be an ACCIDENT or an EMERGENCY. Such happenings may arise from a wide variety of causes ranging from a simple spill of radioactive material to a natural disaster such as flood or earthquake.

1. Priority must be given to human safety according to need and urgency.
2. A serious fire hazard must take precedence over a contamination hazard.
3. Warn all other persons in the vicinity by the most appropriate means. Inform the Departmental Radiation Safety Representative or the Director of Safety as soon as possible.
4. In the case of a spill of radioactive material, without other complications, primary consideration must be given to containment of contamination. The extent of contamination should be determined and the area clearly marked.
5. Persons directly contaminated by a wet spill should immediately remove clothing affected and thoroughly wash the hands and other contaminated areas of the body.
6. If an inhalation hazard exists, all persons not involved in carrying out planned safety procedures should vacate the contaminated area immediately.
7. If evacuation of the room is required, it will generally be desirable to shut off all mechanical ventilation and to close all outside openings. However, there may be local conditions which require consideration. For example, if the release occurs in or near a fume hood, it may be disadvantageous to take any action which would discontinue ventilation by the hood.
8. Except in case of injury or other urgent need, persons who have vacated the contaminated area should not leave the immediate vicinity until they have been monitored and necessary precautions, such as the removal of shoes or outer clothing, have been taken to limit further spread of radioactivity.
9. Re-entry into the affected area must be restricted to properly equipped persons until the area is declared safe by the Director of Safety.
10. All accidents should be fully reported. This report may have an important bearing on staff health and legal responsibilities and may assist the Director of Safety in making a detailed study with a view to avoiding similar accidents in the future.
11. All accidents should be investigated and appropriate measures should be taken to prevent repetition of the accident.

For further details about radiation protection services, please visit the Safety Office website at http://www.hku.hk/safety/.