I live near a power line, or am planning to buy
a house near one. Are there any
health risks I should be aware of?
After
nearly 40 years of research, there are no clear indications of health risks for
adults living near transmission lines, and only weak evidence of possible risks
for children.
If
there are any health effects, people think they may be caused by long term exposures to magnetic fields
produced by the electric currents flowing through the lines. Key points about these are:
- Even
directly beneath a power line, field levels are much lower than the exposure
limit recommended by the Ministry of Health.
- Within
50 – 100 metres of most high voltage lines (those often carried on big pylons),
and a few metres of low voltage lines which distribute power to houses, the field levels have decreased to the “background”
levels produced in all houses by electric wiring and appliances.
What about transformers and substations?
Magnetic
field levels inside houses are not usually affected by nearby transformers or
substations, even if they are next door, or on the street in front of a house.
- Magnetic
fields around small transformers by the side of the road are much lower than
the exposure limit recommended by the Ministry of Health. They normally decrease to the “background”
levels found in most houses within 2 – 3 metres.
- Magnetic
fields around substation boundaries are generally the same as they would be if
there were no substation, except where lines going in and out of the substation
cross the boundary.
How can I know the magnetic field levels near a power line?
Field
levels near a power line vary depending on the amount of power being carried by
the line. Often the levels are highest
in the morning and evening. The table
below shows field levels measured near New Zealand high voltage lines, and in
other places for comparison.
Beneath high voltage lines
|
0.2 – 5 microtesla
|
40 m from high voltage lines
|
0.04 – 0.4 microtesla
|
Near operating electric range
|
1 – 2 microtesla
|
Typical “background” levels in houses
|
0.04 – 0.1 microtesla
|
30 cm from appliances
|
0.05 – 5
|
Recommended limit in New Zealand
|
200 microtesla
|
Other
areas of this site with relevant information are:
Last updated 12 December 2017 |