From Tom Nash
Sherborne, Dorset
There is no scientific basis for Clive Mather’s suggestion that air
pollutants can be “concentrated” near high-tension cables (Letters, 16 March, p
57). As regards direct chemical effects, silent discharges in air generate ozone
but noisy ones oxides of nitrogen.
Domestic air ionisers apply high-voltage DC to a sharp point and the air
blowing off that smells to me more of nitrogen dioxide than of ozone. At high
dilution, the latter has a perfume-like smell, while that of nitrogen dioxide is
“fresh” and reminiscent of celery. I wonder if Jonathan Hobley (ibid) is sure it
was ozone he smelt near a substation? According to the official figures,
nitrogen dioxide is thirty times less toxic than ozone.
