When it’s not good for the sun to shine on you

Employers have a duty to keep their employees safe from the sun. Reuters/Mike Blake

A real-time study using a hand-held device to measure solar ultraviolet radiation value has found that outdoor workers may be heavily exposed to up to 80% of sun rays.

The study was done in South Africa, which has a large number of people who spend the majority of their lives working outdoors. The location was Pretoria, a city north of Johannesburg that gets considerable solar ultraviolet radiation because of its low latitude (22–35°S) and relatively clear skies.

A previous investigation found a direct link between poor health and people working in extreme heat. There were risks of exposure to heat in mining and in particular for outdoor workers in agriculture, quarries and construction industries in hot regions.

Since this was the first case study of its kind in South Africa, our approach was to test the instrument available for measuring sun exposure. We then collected preliminary data on an outdoor worker’s sun exposure patterns. The broader implications of the case study were supported by previous studies into how the sun affects people working outdoors.

There were issues around reliability of the device, which is why a larger study using more better quality, real-time instruments would advance the work further. Such large studies have been done in the US, Europe and Australia, and have led to improvements in occupational health policy with respect to sun protection guidelines. In some cases, such data has helped make skin cancer a notifiable or reportable occupational disease.

Real-time measurement of the sun

The study sought to estimate the amount of solar ultraviolet radiation that outdoor workers are exposed to on a daily basis during work. Although previous studies of this nature have been conducted, it was the first of its kind in South Africa where the estimation was calculated using real-time measurements of solar ultraviolet radiation.

As part of this research a school groundsman was monitored for the duration of the study. Half-hourly solar ultraviolet radiation readings were taken with the hand-held instrument while he was on duty, whether in the sun or shade.

These solar ultraviolet radiation readings were then compared to the solar ultraviolet radiation readings recorded by the research-grade solar ultraviolet radiation recorder at the South African Weather Service in Pretoria.

The amount of solar ultraviolet radiation measured for the outdoor worker was compared to the amount of solar ultraviolet radiation measured by the recorder at the Weather Service. It gave an indication of the amount of solar ultraviolet radiation to which the outdoor worker was potentially exposed. This figure was used to determine whether or not the level of exposure to solar ultraviolet radiation posed a risk of sunburn.

Based on the readings, combined with the findings of previous research, it was found that outdoor workers in Pretoria are potentially exposed to more than 80% of the solar ultraviolet radiation that reaches the ground. This amount of exposure is likely to lead to a high risk of sunburn depending on the time of the year.

With this amount of exposure people of all skin types are at risk of over-exposure to solar ultraviolet radiation and therefore sunburn on at least some days of the year.

Exposure to sun causes skin cancer

A large number of skin ailments in South Africa are linked to the harmful effects of exposure to the sun. The nature of outdoor work dictates that the sun cannot be avoided. This includes farm workers, construction workers, policemen directing, labourers carrying out repairs to roads or collecting refuse.

But they are among the least protected workers in most developing countries. Sunburn, cataracts and skin cancer are the main adverse health effects of excess sun exposure.

The rise of skin cancers and other illnesses associated with ultraviolet rays makes it necessary for employers to take steps to safeguard their employees. The International Labour Organisation has set standards which includes that employers should take safety precautions to reduce risks faced by workers. South Africa is a signatory to the convention.

Employers should encourage the use of protective gear. The use of clothing, including hats, to shield people from the sun, sunglasses and sunscreen are simple recommendations. Devices that measure the impact of the sun on workers should also be considered.


This piece is based on an article in the South African Journal of Science.