Vattenfall aB GeneRatIOn nORDIC CeRtIfIeD enVIROnmental ...

4 Additional environmental information
The International Commission on Non-Ionising Radiation Protection (ICNIRP), an independent
body consisting of international experts, has however published recommendations 1
regarding acute health problems. The recommendations are based on knowledge about
acute health problems due to changing magnetic fields and propose a limit of 500 μT for
working environment and for the general public a limit of 100 μT at 50 Hz. The EU Council
of Ministers recommends a restriction of exposure to electro-magnetic fields in accordance
with the ICNIRP:s recommendations.
According to ICNIRP available research results on lesions due to long-range exposure, for
example raised risk of cancer, do not suffice to establish limits.
Vattenfall follows the precautionary principle, which implies reducing fields that deviate
considerably from normality in each specific case. Vattenfall follows ICNIRP’s, WHO’s and
OECD’s work and recommendations in the area.
4.5 Noise
Sound propagation depends on several factors such as medium, frequency, amplitude,
temperature, humidity, wind, and geography. Consequently noise levels from one and the
same source may vary from day to day. It also means that two identical sources of noise
in different locations may give rise to completely different noise levels and propagation
patterns and may be experienced differently.
The most distinguishing outdoor noise from hydropower generation is the sound of streaming
water at above ground stations. These sound levels are, however, lower than preregulation
and more often than not considered pleasant.
Noise levels from transformers are generally moderate (45–60 dB), but the frequencies
are low (80 dB), which under unfavourable conditions can be disturbing at distances
of up to 1 km. At Porjus, levels of 92 dB(A) 2 have been measured at 1 meter, and of
42 dB(A) 2 at 800 meters from the transformer.
Power lines over 70 kV may give rise to noise (corona noise). Sound levels are moderate -
45 dB(A) 2 at 25 meters decreasing rapidly.
1
Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic, and Electromagnetic Fields
(up to 300 GHz), Health Physics Vol. 74, No 4, pp 494-522, 1998.
2
dB(A) indicates that a standard method of measurement has been used where the value has been
corrected with respect to the sensitivity of the human ear at different frequencies.
© Vattenfall AB Generation Nordic 2008 42