EU turns spotlight on optical radiation hazards and risks

Chris Dyer reports on the introduction of legislation requiring employers to assess the risks at work arising from optical radiation.

The recent "political agreement" on a proposed Directive on optical radiation means that the last piece in the European Union's physical agents legislative jigsaw¹ is almost in place. The agreement was reached under the Dutch presidency of the European Union (EU) at the Council of Ministers meeting on 7 December 2004. Implementation in the UK will require employers, for the first time, to assess the risks to workers' health and safety resulting from their exposure to light.

The proposal follows more than 10 years of EU activity. In April 1993, the European Commission proposed the introduction of a Directive to control the exposure of workers to the risks arising from physical agents. It subsequently issued a revised proposal in August 1994 to take account of European Parliament amendments.

The 1994 proposal set out a framework of harmonised requirements with specific provision in separate annexes for noise, vibration (hand-arm and whole body), optical radiation and electromagnetic fields. Other agents could be added later. The annexes laid down exposure levels, above which employers had to take action, including risk assessment, measurement, preventive and control programmes, provision of personal protective equipment and health surveillance.

In 1993, UK Ministers accepted advice from the HSC that the proposal was not necessary and should be withdrawn by the Commission while its potential impact was studied or, failing this,its scope should be restricted to vibration and, preferably, to hand-arm vibration alone. The UK was not alone in opposing the proposal and, although member states' views of the proposal varied, it was not widely supported.

As a result there was no further formal activity on the proposal until 1999 when the German Presidency of the EU suggested that the agents should be taken sequentially in separate Directives:

Optical radiation

The fourth proposal, on optical radiation, covers electromagnetic radiation in the wavelength range 100 nm to 1 mm. It includes ultraviolet, visible and infrared radiations and lasers. Light is usually "non-coherent": it comprises many wavelengths and issues from a source in all directions. But it can also be "coherent", as when it is concentrated into a beam of a single wavelength emitted by
a laser.

The greatest risks to health are from ultraviolet radiation and powerful lasers. Lasers are classified according to their power, and low-powered devices, such as those used in barcode readers, do not pose any harm. The major risk is from an uncontrolled exposure to a powerful laser due to an incident or other unexpected event. Although some industrial sources of ultraviolet light could lead to significant exposure, the main source of exposure is the sun. The wavelength and intensity of optical radiation determines which tissues are at risk from exposure, although this will usually be either the skin or the eye: tissues at depth are unlikely to be at risk.

In the case of the eye:

In the case of the skin:

ultraviolet radiation can cause erythema (skin reddening), burning, blistering, premature skin ageing, eye disorders and an increased risk of skin cancer; and

powerful lasers can cause skin burns.

The International Commission on Non-Ionising Radiation Protection (ICNIRP) has published guidelines on limits of exposure for non-coherent and coherent light sources and these are used as the basis of the exposure limits set out in the proposed Directive. In the case of workers exposed to artificial sources of optical radiation, the proposal requires an employer to assess and, if necessary, measure and/or calculate the levels of exposure so that measures needed to restrict exposure to the applicable limits can be identified and put into effect (see box 1 ). In day-to-day work, the acute effects of exposure should not occur as artificial sources of optical radiation are shielded to prevent undue exposure.

Solar exposure

The sun is the main source of exposure to optical radiation for most people. People who work outdoors can experience the effects of too much sun on their bodies if they are reluctant to take sensible precautions to minimise exposure. The levels of ultraviolet radiation reaching the Earth's surface depend on the time of year, the transmission properties of the atmosphere and the power output of the sun. Outdoor workers' exposure is also affected by local climate and the geometry and length of exposure. In addition, the eye has natural aversion responses that limit exposure.

These factors mean it is difficult to apply the ICNIRP limits to optical radiation exposure from the sun in a meaningful way, particularly in relation to eye exposures. A precautionary approach has to be adopted to keep exposures below thresholds for short-term health effects and to limit the risk of long-term damage. The proposed Directive requires an employer, in the case of workers exposed to natural sources of optical radiation, to assess the risk to health so that the measures needed to minimise these risks can be identified and put into effect. The assessment must be based on the advice and guidance of expert international health advisory authorities. The HSE has produced non-binding guidance to employers and workers on ways to reduce exposure (see box 2). The National Radiological Protection Board (NRPB), which has been advising the HSE on the implications of the proposed Directive, calculates that approximately one million employees who work out of doors regularly could be subject to assessment and the implementation of controls.

Potential implementation problems

There is no UK legislation specific to optical radiation. The general duties to assess and control risks contained in the HSW Act and the Management of Health and Safety at Work Regulations 1999 apply. In general though, control is exercised by compliance with international and national guidelines.

Any industry that uses or generates an intense source of light has the potential to create optical radiation levels that exceed the proposed exposure limits if control measures fail. These industries include chemical and biological research, engineering, dentistry, furniture manufacture, medical practices, opticians, police, horticulture, metalworking, printing, food preparation, glassware, ceramics and retail. The NRPB anticipates that the major burden imposed by the proposal will be in terms of non-coherent optical radiation where all employers will have to demonstrate compliance. Employers that do not make use of specialised sources of optical radiation will still have sources of optical radiation at their premises, such as general area and task lighting and photocopiers. The "burden" is not in carrying out a risk assessment, which employers are under a general duty to do anyway, but in gathering objective data towards the assessment, including quantifying the hazard. A hazard assessment will be required to identify all sources and to verify that they do not pose a hazard; this is a potentially expensive exercise, as an objective judgment will need to be based on radiometric measurement.

This problem may be relieved by use of a standard for lamps and lamp systems developed by the International Commission on Illumination. A risk group classification scheme provides common ground for both lamp manufacturers and users to define the specific photobiological hazards of any given lamp or lamp system. The NRPB believes that if all lamps, lamp systems and machines placed on the market are classified according to this standard, most hazard assessments will be reduced to an exercise in cataloguing sources and their attached classifications. The HSE has not yet planned how to deal with the details of any problems raised by the proposal, although it is broadly happy with the text.

Coherent light issues

The use of coherent light from lasers in the workplace is growing; applications include etching and welding metals, removing diseased tissue, treating eye conditions and barcode readers. For many applications, the optical radiation is, or can be contained, by engineering control measures. The impact of the proposed Directive for these applications is negligible, although maintenance and servicing operations will have to be considered.

The NRPB identifies further areas where the proposal could prove problematic for employers.

The HSE advises that because the proposed text is an amendment to the European Commission's 1993 physical agents proposal, rather than a new proposal, it has not been published formally and is subject to confidentiality requirements.

The HSC has not been able undertake a formal consultation but, as with the previous physical agents proposals, it has consulted informally and has made successive texts available on its website.

The proposed Directive will now go to the European Parliament for its second reading after which, subject to agreement on any amendments introduced by the parliament, it will be adopted. The HSC will then consult on draft Regulations needed to implement the Directive in the UK, but it is likely to be at least four years before these come into force.

¹ "Draft proposal for a Directive of the European Parliament and of the Council on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (optical radiation) (19th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC)", www.hse.gov.uk/radiation/nonionising/issues.htm, free.

Chris Dyer is a former editor of HSB.