Use of Ultra-Violet Light Sources

Ultraviolet Radiation is that portion of the electromagnetic spectrum that falls in the region of 100 to 400nm. This spectrum has been divided into three regions:-

• A: 400nm to 315nm known as Near UV or UV-A,
• B: 315nm to 280nm known as Mid UV or UV-B,
• C: 280nm to 100nm known as Far UV or UV-C.

Hazards

Two categories of hazard are involved in the use of high intensity UV lamps: those inherent in the radiation itself and those associated with operation of the lamps. All radiation of wavelength shorter than 250 nm should be considered dangerous.

• Damage to eyes and skin caused by exposure to UV radiation. Repeated overexposure of skin to UV has been linked with premature aging, wrinkles and most seriously, skin cancer. Eye damage can result in corneal scarring and cataract formation.
• Burns caused by contact with a hot UV lamp.
• Fire ignited by hot UV lamp.
• Interaction of other nearby chemicals with UV radiation.
• Damage caused to apparatus placed close to UV lamp.

Risks

Damage to vision is likely following exposure to high intensity UV radiation.

Who is likely to be injured?

The User or anyone exposed to the UV light as a result of faulty procedure. Injuries may be slight to severe.

Control Measures.

Operating Precautions

Lab-coats, gloves and safety glasses or other appropriate eye/skin protection such as UV protective glasses or a UV protective face shield must be worn.

Reactions using UV lamps: external irradiation sources.

• These operations must never be attempted by an untrained person.
• These operations must never be attempted by a single person.
• These operations must never be attempted out of normal working hours.
• Use of UV lamps must be carried out in a fume hood with boarded up windows.
• As far as possible, the UV source should be contained in a closed radiation box.
• The fume hood sash must remain closed while the UV lamp is switched on.
• The fume hood may contain only the UV lamp and associated apparatus and chemicals. No other chemicals are to be stored in the fume hood and no other reactions are to be performed in the fume hood.
• Reaction vessels containing flammable solvents must be at least 20 cm away from the lamp to avoid excessive heating.
• Flammable equipment (e.g. rubber/plastic tubing) must be positioned at least 10 cm away from the lamp.
• After the UV lamp is switched off, unless the reaction mixture requires immediate attention, the fume hood sash should remain closed for 30 minutes to allow the UV lamp to cool.

Reactions using UV lamps: low/medium pressure Hg lamps in an immersion well.

• These operations must never be attempted by an untrained person.
• These operations must never be attempted by a single person.
• Low/ Medium pressure lamps are to be used ONLY in approved, water-cooled immersion well apparatus.
• The UV lamp power supplies must incorporate an electrical cut-out that activates in the event of disruption to cooling water.
• The UV lamp must not be switched on until:
• The glassware is shrouded in Al foil,
• The immersion well set-up is shielded by the appropriate metal case
• The boarded up fume-hood doors are closed.
• The UV lamp must NEVER be switched on/connected outside of the shrouded immersion well apparatus.

Training

For the use of high intensity UV sources, new users must be trained by another member of the laboratory who, in the opinion of the member of staff in charge of the laboratory, is sufficiently competent to give instruction on the correct procedure. Newly trained users should be overseen for some time by a competent person.

Level of Risk Remaining

Low if the above precautions are followed.

Back to Completed Risk Assessment Forms

Adapted with permission from School of Chemistry, University of Bristol