Tougher rules on hazardous emissions from waste incinerators were announced by the Government yesterday.

Michael Meacher, the Environment minister, said new limits would reduce dioxins in the air emissions to no more than one part in ten billion to protect the environment and human health.

More than a third of British adults are exposed to levels of dioxins in excess of the daily limit recommended by the World Health Organisation, though some of it comes from food. Scientists believe toddlers are exposed to more than twice the recommended level and breast-fed babies up to 170 times the recommended level.

Mr Meacher said: "Dioxins are toxic and potentially dangerous but have been reduced to absolute minute levels by an already operating EU directive. The level has now been tightened tenfold."

The EU directive, to be implemented in England and Wales by the end of 2005, sets a new limit for dioxin emissions at a tenth of the previous limit. It also introduces tougher operating conditions for incinerators burning municipal waste, smaller plants including clinical waste incinerators and cement kilns. Around 950 directives in England and Wales will be affected by the new rules. The Environment Agency, which is responsible for regulating and monitoring dioxin emissions from large incinerators, admitted that some plants might have to close.

Friends of the Earth called for more investment in recycling so that more incinerators would not have to be built.

Norman Baker, the Liberal Democrat environment spokesman, welcomed the measures, but called for all incinerators to be phased out.

There have been concerns that the monitoring of pollution from incinerators has been inadequate. Yesterday the Environment Agency admitted that operators were given advance information on when inspectors would turn up.

An official said: "We do once-a-year checks and send in our officials. The difficulty is we can't just walk in with our gear to start monitoring. We give them a four-week window of opportunity. We don't tell them exactly when. It's very difficult for the operator to be totally dishonest."