[Research result] Study shows the danger for Capetonians and tourists visiting Table Mountain.

UV index defined by the World Health Organization.


A ten-year climatological and atmospheric scientific study indicates high levels of UV radiation exposure in Reunion Island (French territory) and Cape Town (South Africa) and highlights the need to increase awareness among the population and tourists hiking on Table Mountain.

Maximum UV index distribution from July (left) to June (2009 to 2018).

© J.-M. Cadet et al., Atmosphere 2019, 10, 589.

A South African – French team of scientists conducted a 10-year climatology study using ultraviolet radiation measuring instruments based at the University of Reunion Island, in Saint-Denis, and at Cape Town international airport. The results show very high UV radiation exposure, especially during the austral summer, often reaching the “extreme” category (more than 11) on the World Health Organisation UV index.

The black line represents the cumulated dose. The horizontal lines show the threshold for 1 dose to sunburn as function of skin phototype.

© J.-M. Cadet et al., Atmosphere 2019, 10, 589.

The researchers coupled these long-term assessments with case studies conducted at two popular hiking sites at relatively high altitude, namely Maïdo-Grand Bénare hike in Reunion Island and Table Mountain via Platterklip Gorge in Cape Town. Tourists, hikers and employees of the Table Mountain National Park are confronted with extreme exposure and very high cumulative UV doses during their time at high altitude. The field measurement indicates that hikers going through the gorge accumulate a total exposure dose of 40 SED (Standard Erythemal Dose) during one hike, corresponding to 3 to 25 times the minimal dose required to elicit a sunburn response for the majority of skin types (phototype I to VI).

Harmful effects

Measurement of UV radiation exposure.

© Hassan Bencherif

Capetonians and tourists on Table Mountain are thus often exposed to high UV levels with potential consequences on their skins and health if not properly protected. “These high levels may be dangerous for people spending extended periods of time outdoors. This can result in sunburn, skin damage or even skin cancer”, says Prof. Hassan Benchérif, from the University of Reunion Island, coordinator of the CNRS project on atmospheric science “ARSAIO”. The study highlights the importance of implementing appropriate public awareness campaigns on the UVR exposure-risks. “We need to sensitize everyone to these dangers, especially since climate change could lead to a higher risk in the next decades”, concludes Prof. Benchérif.


Cadet, J.-M.; Bencherif, H.; du Preez, D.J.; Portafaix, T.; Sultan-Bichat, N.; Belus, M.; Brogniez, C.; Auriol, F.; Metzger, J.-M.; Ncongwane, K.; Coetzee, G.J.R.; Wright, C.Y. Solar UV Radiation in Saint-Denis, La Réunion and Cape Town, South Africa: 10 years Climatology and Human Exposure Assessment at Altitude. Atmosphere 2019, 10, 589.
Download the article: https://www.mdpi.com/2073-4433/10/10/589

This article was produced thanks to the collaboration of CNRS, University of La Réunion, South African Weather Service, South African Medical Research Council, University of KwaZulu-Natal, University of Pretoria, Centre Hospitalier Ouest Réunion, Conseil Régional de la Réunion, LACy (Laboratoire de l’Atmosphère et des Cyclones), University of Lille, Observatoire des Sciences de l’Univers de la Réunion.