drive the human body. Nerves relay signals by transmitting electric impulses, for example, while the use of electrocardiograms testify to the electrical activity of the heart.
Campaigners have long been worried about exposure to fields from lines carried by electric pylons but, until recently, their concerns were dismissed, even ridiculed, by the authorities.
But last year a study by the official National Radiological Protection Board concluded that children living close to the lines are more likely to get leukaemia, and ministers are considering whether to stop any more homes being built near them. The discovery is causing a large-scale reappraisal of the hazards of the smog.
The International Agency for Research on Cancer – part of the WHO and the leading international organisation on the disease – classes the smog as a "possible human carcinogen". And Professor David Carpenter, dean of the School of Public Health at the State University of New York, told The Independent on Sunday last week that it was likely to cause up to 30 per cent of all childhood cancers. A report by the California Health Department concludes that it is also likely to cause adult leukaemia, brain cancers and possibly breast cancer and could be responsible for a 10th of all miscarriages.
Professor Denis Henshaw, professor of human radiation effects at Bristol University, says that "a huge and substantive body of evidence indicates a range of adverse health effects". He estimates that the smog causes some 9,000 cases of depression.
Perhaps strangest of all, there is increasing evidence that the smog causes some people to become allergic to electricity, leading to nausea, pain, dizziness, depression and difficulties in sleeping and concentrating when they use electrical appliances or go near mobile phone masts. Some are so badly affected that they have to change their lifestyles.
While not yet certain how it is caused, both the WHO and the HPA accept that the condition exists, and the UN body estimates that up to three in every 100 people are affected by it.
Case History: ‘I felt I was going into meltdown’
Until a year ago, Sarah Dacre reckoned she had a "blessed life". Running her own company, and living in an expensive north London home, the high-earning divorcee described herself as "fab, fit and 40s". Then suddenly the sight in her right eye failed: she first noticed it when she was unable to read an A-Z map. Soon she was getting pains and numbness in her joints. She could not sleep and spent nights "pacing about like a caged lion". Her short-term memory failed and if she took notes to remind her, she would forget she had made them.
The symptoms got worse whenever she was exposed to electricity. She could not use a computer for more than five minutes without becoming nauseous. Even using a telephone landline gave her a buzzing in the ear and made her feel she was "going into meltdown".