The Department of Labour says not enough outdoor workers are aware of the need to monitor their skin for early warning signs of possible skin cancer.
New Zealand leads the world in the incidence of melanoma.
The department says outdoor workers are particularly vulnerable, working long periods in the sun and often during the time of harshest ultra-violet light, the middle of the day.
Its chief adviser on health and safety, Geraint Emrys, says employers are obliged to protect their employees.
But he says workers can help themselves as well by checking their skin every few months, because 90% of cases of skin cancer can be cured if caught early.