Solar ultraviolet radiation exposure among opencast miners in Namibia with the use of electronic dosimeters : a feasibility study

Abstract

IMPORTANCE: The lack of information on exposure of opencast mineworkers to solar ultraviolet radiation, a group I carcinogen, was addressed. The feasibility of using electronic dosimeters in the determination of exposure to solar ultraviolet radiation was investigated. OBJECTIVE: The objective of the study was to determine the feasibility of measuring the occupational exposure of opencast mineworkers to solar ultraviolet radiation using electronic dosimeters. DESIGN: The study followed a cross‑sectional design. SETTING: Measurements were carried out at two opencast diamond mining operations hereafter referred to as site A and B, located in the Karas region of Namibia. PARTICIPANTS: Workers from all four outdoor occupations (bedrock, engineering, metallurgy and security) were recruited to participate in the study. MEASUREMENTS: The study was conducted over four days at each site during winter (site A: 28 June to 4 July 2018 and site B: 6–11 July 2018) in the Karas region of Namibia with 28 consenting workers taking part. The AlGaN photodiode‑based electronic dosimeters were worn above clothing on the dorsal wrists (one) and two placed on the horizontal, unshaded area from 08:00 to 16:00 for the measurement of personal and ambient solar ultraviolet radiation, respectively. Historical meteorological data for the measurement period were obtained from Solcast and Ozone Monitoring Instrument (OMI) NASA. RESULTS: Overall, clear skies and surface reflectivity of 0.19 were observed for both study sites. The mean ultraviolet indices were 2.43 (0.06–4.51) and 2.24 (0.09–4.88) for site A and B, respectively. Findings of valid measurements from nine participants showed the mean total daily personal solar ultraviolet radiation exposure of 1.9 ± 1.0 (1.01–1.57) standard erythemal dose (SED) for site A and 3.4 ± 2.6 (3.39–7.28) SED for site B. Conclusions and Relevance: Personal solar ultraviolet radiation exposure above the occupational exposure limit (OEL) demonstrated the need to include the winter season in planning for protective measures for skin and eyes, since workers are at risk of excessive exposure to solar ultraviolet radiation.