IOSH Report: Construction Workers Encounter Excessive Exposure to UV Radiation

What is the solar ultraviolet (UV) radiation burden on construction workers in the UK?

Sunlight is a source of vitamin D, which helps the body absorb calcium and phosphate. Without vitamin D, bones can become soft and weak, eventually leading to bone deformities.[i] Nevertheless, relying too much on UV radiation as a vitamin supplement can cause non-melanoma skin cancer (NMSC).

Ideally, outdoor workers, including construction workers, should attempt to reduce UV radiation in summer and increase their vitamin D intake in the winter, to avoid vitamin deficiency.

Currently, research on UV exposure levels is limited. However, the Institution of Occupational Safety and Health (IOSH) has incentivised solar radiation as a key component of its No Time To Lose (NTTL) campaign objective to prevent occupational cancer.

For more information on the campaign, read our latest feature article on occupational UV radiation claims here and our article on free NTTL practical materials here.

Most recently, IOSH funded a collaborative study, conducted by Heriot-Watt University, the University of Edinburgh and the Institute of Occupational Medicine, in an attempt to understand how ‘sun-safe behaviours’ can be improved.[ii]

As such, the investigation was effectively separated into 2 parts.

  1. UV exposure in high-UV summer.
  2. Vitamin D intake in low-UV winter.

Data was collected from 9 construction sites in Central Scotland and Greater London. Each exposure period (2 in winter and 1 in summer) lasted 21 days.

UV Exposure in Summer

In the summer, UV exposure was measured with wearable electronic sensors on the back of construction worker hard hats. Measurements were taken in the form of a standard erythemal dose (SED), averaged over an 8-hour-day.

The International Commission on Non-ionising Radiation (ICNR) recommends a daily exposure limit of 0.3 SED for those with ‘light-coloured skin’. Daily exposure above 2 SED carries a high risk of sunburn.

Results showed that workers who spent their time ‘predominantly outdoors’ were exposed to an average of 2 SED (with 40% above that level), while those who spent their time ‘partly indoors and partly outdoors’ were exposed to an average of 0.69 SED (with 12% above sunburn risk levels).

The researchers concluded that, over the course of a working lifetime, the recorded levels were associated with a significantly increased risk of NMSC. In many cases, unprotected exposure was a conscious, deliberate choice.

Vitamin D in Winter

In the winter, vitamin D concentration was measured by way of blood sampling.

This revealed that around 50% of outdoor construction site workers had insufficient vitamin D levels, as UV levels were too low to be synthesised naturally.

Smartphone Messaging to Induce Behavioural Change – Effective or Not?

To assess whether worker safety and health could be enhanced, groups of workers during both seasons received short, smartphone messages (to reduce UV exposure in summer and increase vitamin D intake in winter) as a form of intervention.

In the summer study period, the intervention was unsuccessful at influencing workers to take protective measures. The researchers attributed this unchanged behavioural response to the ‘widespread misconception’ that having a sun tan is healthy.

A difference was seen, nonetheless, in winter. The intervention yielded a higher proportion of workers with sufficient vitamin D levels in both the 1st (48% to 88%) and 2nd (53% to 70%) winter study periods. The researchers therefore implied that daily information and availability of a dietary supplement can be used to boost vitamin D levels.

IOSH Research Manager, Mary Ogungbeje, analysed the outcomes of the smartphone intervention, as follows:

‘We have known that behaviour change strategies specifically targeting health risk factors can be effective. What we didn’t know is how effective the use of everyday technology can be in encouraging safe, healthy attitudes and behaviour among outdoor workers. The findings are promising but highlight that there’s some work to do as both workers and employers have a part to play in reducing the risks of excessive UV exposure’.

Access to the IOSH report can be obtained here.


[i] ‘How to get vitamin D from sunlight’ (31 August 2018 NHS) <> accessed 22 March 2019.

[ii] ‘Skin cancer risk for construction workers’ (21 March 2019 Health & Safety Matters) <> accessed 21 March 2019.