UV Exposure to Outdoor Workers from the Sun

9. (1990)

Solar Radiation. In addition to visible light, solar radiation also contains ultraviolet (UV) radiation. The UV region is conventionally split into A, B, and C wavelength bands, as follows:

UV Radiation below 180 nm is absorbed by air and hence this component of solar radiation is not present at the earth's surface. Absorption of solar UV by the ozone layer of the upper atmosphere accounts for the absence of the UV-C wavelengths and the limited amount of UV-B in terrestrial solar radiation.

Effects of Acute Exposure to UV. UV is relatively non-penetrating through body tissue, so the effects of UV exposure are limited to the skin and to the cornea and lens of the eye. Acute effects of exposure to UV-B,C are sunburn (erythema) for the skin and corneal inflammation (photokeratitis) for the eye. There is normally a delay of 4-8 hours between exposure and manifestation of the effect.

Effects of Chronic Exposure to UV. Chronic exposure to significant levels of UV-B over time produces a loss of elastic property in the skin (premature skin aging) and is a known risk factor in the development of skin cancer and of opacities in the lens of the eye (cataracts). Cataracts may ultimately produce blindness.

Recently, concern has been expressed that the levels of UV-B in solar radiation is such, or may become such, that outdoor workers may be more likely to develop a cataract over the course of a working lifetime than the general population [1]:

A study published in the New England Journal of Medicine shows a link between Ultra Violet B radiation (UVB) and cataract development.

The study involved 838 watermen in Chesapeake Bay, Maryland, U.S., and showed that workers who developed cataracts had a higher annual exposure to UVB rays than those who did not.
Dr Ted Emmett, Chairman of Worksafe Australia and co-author of the study, said the risk of eye damage was even more critical now because of the significantly higher levels of UVB which are predicted to result from the reduction in the ozone layer.
Cataracts occur more commonly in tropical or sunny areas. More than 17 million people worldwide are blinded by cataracts.
"In addition to the well-known risk of skin cancer, outdoor workers must protect their eyes from UVB radiation by wearing a hat with a brim and sunglasses with UVB absorbing lenses" Dr Emmett advises.

Exposure in Vehicles and Indoors. Levels of solar UV-B in cars and indoors is very low because of the good absorption properties of ordinary window glass for UV-B [2].

Recommendations for Outdoor Workers. Occupational groups, such as welders, that generate UV as part of their work activities have long recognised the problems associated with excessive exposures to UV and use appropriate personal protective equipment to control to their skin and eyes.

It is important that outdoor workers (including employees undertaking a significant amount of outdoor field work) be encouraged to adopt a similar attitude towards long-term dose control of UV to their skin and eyes. It is recommended that as part of the strategy for effective control of solar UV exposure for outdoor workers:

• work practices be adopted that avoid sunlight at its most intense (10 am - 2 pm standard time; 11 am - 3 pm daylight saving time) by working indoors or under shade,
• a stock of #15 or #15+ sun screen be available for the use of such employees,
• that such employees be issued with, and requested to wear whenever outside,
• a broad brimmed hat,
• a pair of UV-absorbing spectacles (or UV-absorbing safety spectacles, as relevant) complying with Australian Standard AS 1067 Sunglasses and Fashion Spectacles - Non-prescription Types.

Information on the sources of supply of such personal protective equipment is available from the OHS Unit.

References

1. CCH, Workplace Health and Safety Manual
   Recent Developments, 3 May 89
   CCH International, Sydney, 1989 2.
2. American Industrial Hygiene Association
   Non-ionizing Radiation Guide Series: Ultraviolet Radiation
   AIHA, Akron OH, 1977

For further information contact:
OHS Officer, e-mail: OHS.Officer@anu.edu.au