UV exposure on ski-field at an Alpine site
A.M. Siani, G.R. Casale,
Sapienza - University of Rome, Dept. of Physics, Rome, Italy
H. Diémoz, G. Agnesod,
ARPA Valle d'Aosta (Aosta Valley Regional Environmental Protection Agency), Saint-Christophe (Aosta), Italy
M. Borra, A. Militello,
ISPESL, (Italian National Institute of Occupational Safety and Prevention), Occupational Hygiene Dept., Monteporzio Catone (Rome)
Italy
M. G. Kimlin, C.A. Lang,
Australian Sun and Health Research Laboratory, Queensland University of Technology, Institute of Health and
Biomedical Innovation, Brisbane, Australia
A. Colosimo
Sapienza - University of Rome, Dept. of Human Physiology and Pharmacology ,Rome, Italy
Abstract. The purpose of our study was to assess
personal UV exposure of two groups of volunteers (ski
instructors and skiers) at the Alpine site of La Thuile (Valle
d’Aosta region, Italy) using polysulphone and electronic
dosemeters.
Introduction
The amount of solar ultraviolet (UV) radiation at the
Earth’s surface depends on the incoming solar energy and
the transmission properties of the atmosphere as well as
the features of the site (surface topography and albedo).
Mountain sites experience enhanced ambient UV radiation
levels due to the concurrent effects of shorter radiation
path-length, low aerosol load and high reflectivity of the
snow surface. Although several studies of UV radiation at
high altitude sites were carried out (Blumthaler et al, 1997;
Schmucki and Philipona, 2002; Pfeifer et al., 2006), little
is known about UV exposure of human beings in
mountainous areas where outdoor working or recreational
activities (such as skiing) occur. The Alps are one of the
places where the highest values of UV levels in Europe
(Schmucki and Philipona, 2002) are experienced and
tourism is leading more and more people into ski fields
with the result that not-protected skin and eye can be
damaged due to the overexposure to UV radiation. Thus,
the aim of our work was to assess personal UV exposure
of two groups of skiers (ski instructors and skiers) at the
Alpine ski field of La Thuile-Les Suches (2100 m a.s.l.) in
Valle d’Aosta region (Italy).
Measurements
Broad-band radiometers, having an erythemal response,
yield measures of the ambient erythemal ultraviolet
irradiance (dose rate) between 280 and 400 nm. Spectral
irradiance undertaken with a spectroradiometer and then
convolved with the C.I.E. erythema action spectrum
(1987) can provide an alternative way to quantify the
ambient UV dose rate. The quantification of human UV
exposure is indeed a complex issue as it is directly linked
to ambient UV dose as well as to behavioural and cultural
factors. Polysulphone dosimetry is a reliable and widely
used methodology (Kimlin, 2005) to assess UV exposure
of differently oriented surfaces and can be used in remote
and not easily accessible places.
In this study a spring (March 30-April 4, 2006) and a
winter (January 29-30, 2007) field campaigns were carried
out at La Thuile-Les Suches ski field (45.7°N, 6.6°E,
2100m a.s.l) under almost clear sky conditions (Fig.1)
from h: 10:00 LT to 16:00 LT. During the campaigns the
maximum UV index was 6.0 and 2.0, respectively. Twenty
skier volunteers and thirteen ski-instructors participated in
the field experiments. Polysulphone dosemeters were
attached on the hat to the forehead of volunteers in order to
better represent their face exposure. Each volunteer was
provided with a set of three PS dosemeters to be changed
every two hours to avoid saturation, and a questionnaire
asking for a description of the activity within each
two-hours period, body posture and time intervals spent in
the shade or indoor. Electronic dosemeters (Giga Hertz
X-2000) were also worn by some volunteers as additional
sensors to evaluate UV exposure. Ambient ultraviolet
doses were measured using the well calibrated broad-band
UV-S-AE-T radiometer (Kipp&Zonen). In addition UV
doses were also recorded by a YES UVB-1 and by a
Bentham spectroradiometer at Saint Christophe (Aosta)
(45.8°N, 7.4°E, 569m) and at Les Granges (45.7°N, 6.6°E,
1640m) by a second UV-S-AE-T broad band radiometer.
All UV instruments belong to the ARPA Valle d’Aosta.
The three sites were chosen in order to study the albedo
and altitude effect on polysulphone calibration curves
(ambient doses versus the corresponding change in PS film
absorbance (ΔA at 330nm), prior and post exposure
(Kimlin 2005). In addition, measurements of skin
reflectance using the Minolta Spectrophotometer
CM26000d (Minolta, Osaka, Japan) were carried out
before and after the exposure on a non exposed skin and
on the cheek.
as measured by the PS dosimeter and the corresponding
ambient dose, was used. Thus, Exposure Ratio is the
fraction (%) of the ambient UV radiation received by each
volunteer during the exposure time intervals. It was found
that during the spring field campaign the ambient UV dose
(UVD) from h: 10:00 to 12:00 LT was 953 J/m2, from h:
12:00 to 14:00 UVD was 1192 J/m2 and then in the last
120min UVD was 879 J/m2. ER showed an average value
of 100% with a minimum of 32% and a maximum of
175%. Exposure derived by electronic dosemeters will be
further analyzed
Conclusions
Fig.1 La Thuile-Les Suches field ski
Preliminary results
A careful quantification of the calibration curve is
required when polysulphone dosimetry is used to evaluate
personal UV exposure. The dose-response relation is
represented by the typical best fit to a third degree
polynomial and it is parameterized by a coefficient (c)
multiplying a cubic polynomial function. It was found by
Casale et al., (2006) that c values can range from 0.78 to
1.85 kJm-2 depending on ozone amounts and solar zenith
angle (SZA). In Fig.2 PS calibration curves for the spring
campaign are shown. Measured c values are 1.69±0.02 at
Les Suches, 1.47±0.01 at Les Granges and 1.24±0.01 at
Saint Christophe.
This study was conducted to assess UV exposure in
terms of Exposure Ratio, in an environment of high
ultraviolet light exposure such as a mountainous site in the
Alps. The average personal UV exposure resulted in being
the same as (and in some cases even more than) the
ambient UV radiation while as reported by Gies in the
WHO report (2006), UV exposure can vary from 5% to
15% of total ambient UV radiation and for outdoor
workers exposures can reach 20-30%. Furthermore the
preliminary results indicate that no difference among ER
values of instructors and skiers were found as expected.
Further multivariate analysis on colorimetric parameters
used as biological indicators of individual response to UV
dose will be carried out.
Acknowledgements
This work was supported by ARPA Valle d’Aosta. The
authors would like to thank the instructors of the La Thuile
ski school and Espace S.Bernardo Funivie which kindly
hosted the UV instruments and all volunteers of ARPA.
References
Fig.2 Simultaneous calibration curves at La Thuile-Les Suches,
Les Granges, Saint Christophe 31/03/2006.
These values are higher than those obtained
theoretically (Casale et al, 2006) when total ozone of 330
DU and SZA between 41° and 58° were taken into account.
The percentage difference between measured and
theoretical values are 44%, 35% and 25% respectively.
This can be due to the contribution of the multiple
reflections from snow which enhances UV exposure. The
albedo effect will further be investigated analyzing the
results of the winter field campaign and also in absence of
snow.
To quantify personal exposures, Exposure Ratio (ER), i.e.
the ratio between the erythemally weighted absorbed dose
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