Industry spokesmen said some provisions of the House version might even be less costly for manufacturers because they might not require the use of expensive pollution-control technology.

But new engines, with pollution-control technology, open the way for more diesel-powered light trucks and sport utility vehicles.

But the additional pollution-control technology is expensive, and many plants across the country have closed.

The park does, however, require that all snowmobiles use noise- and pollution-control technology and that sledders travel with guides, who enforce strict rules.

Companies applying for permits can be ordered to install expensive pollution-control technologies.

And it has made degradable plastics one of the most talked-about pollution-control technologies.

This included $6.2 billion for new power plants, $1.1 billion in tax breaks to install pollution-control technology and another $1.1 billion to make coal a cost efficient fuel.

There are other explanations for the disappointing progress in reducing ozone levels, including the limitations of existing pollution-control technology and the increasing number of cars on the road.

Eventually, it was assumed, the company would have to update its equipment, at which point new-source rules required the company to install the best available pollution-control technology.

In contrast, Southern California Edison says it can meet its emissions requirements more cheaply by buying credits than by investing in additional pollution-control technologies itself.