Increased asbestos and dioxin in New York air - but 'no risk'

Mayor Rudolph Giuliani said today there is no cause for alarm over increased levels of asbestos and dioxin in city's air following the destruction of the World Trade Center.

The levels remained within those considered as medically tolerable, he said.

Dioxin, a by-product of manufacturing processes, is an extremely toxic organic compound and asbestos, a highly heat resistant fibrous silicate mineral, is blamed by doctors for lung cancer cases.

Giuliani said short-term exposure to asbestos was not injurious to lungs, and that generally only breathing in the fibres over long periods of time caused any lasting damage to health.

The US environmental secretary, Christie Whitman, has said that the federal Environmental Agency (EPA) was checking air pollution levels round the clock, and that none of the upper limits for dangerous substances, including lead, had been exceeded or that counter-measures were necessary.

During the end of the 1960s and early 1970s, the time that the twin towers of the trade center were being built, lead was used in the production of paints and synthetic materials.

Unconfirmed reports have suggested that huge quantities of asbestos fibres were released into the air by the inferno and collapse of the two towers.

It was reported, however, today that the towers had been among the first US high-rise buildings in which the steel beams had not be insulated with asbestos.

Instead, a spray-on ceramic fire-proofing material had been used, according to the National Counsel of Structural Engineers Associations, a trade group that had studied the original plans.

EPA officials said Wednesday that testing, nevertheless, showed elevated asbestos levels in the rubble, perhaps from flooring materials or other substances.

Deep uncertainty remains about what sorts of environmental hazards may be contained in the rubble, especially with regard to dioxin.

Several experts have voiced fears that enormous heat generated by the explosion of fuel from the two aircraft, which bored into the towers, could have resulted in the release of large quantities of dioxin.