C. Arden Pope III, an economist who has studied the health effects of fine particulate pollution, takes issue with an EPA committee chairman who minimized the risks involved.

"The evidence for health effects has not weakened. In fact, it has grown," Pope said, challenging the opinions of George T. Wolff, chairman of the EPA's Clean Air Scientific Advisory Committee.The committee is reviewing EPA criteria as part of a court-ordered evaluation of the pollution standards. The American Lung Association sued the EPA to force a re-examination after studies conducted by Pope indicated that people were becoming sick or dying because of particulates that were within federal limits for safe exposure.

Wolff, in a letter to EPA Administrator Carol M. Browner, said the data in the EPA document defining particulate pollution does not adequately demonstrate links between pollution and illness, nor does it suggest what component of the particulates causes the problem.

Wolff said those issues would have to be resolved before the committee could issue its formal findings on the pollution criteria.

Pope said the EPA criteria document is not perfect, but Wolff took the wrong avenue in attacking it.

"This is not clearly what the people on the committee think," Pope said.

Pope said there is a connection between particulate levels and illness, and there is also evidence to show that weather is not a factor, as Wolff hinted.

The unresolved question, Pope said, is exactly which component of particulates causes illness and death, not whether the pollution itself is a culprit.

Particulates come in the form of dust, soot from fireplaces and smokestacks, or a combination of chemicals.

In his own studies, which included an examination of 500,000 people in 151 cities, Pope found higher incidents of illness and death when air pollution levels were elevated. In some cases, the levels were close to what the EPA says is safe.

The studies have led to calls for either lowering the levels considered safe or basing the standards on finer particles that can travel farther into the lungs and cause more damage.

The committee's report will be used to determine whether the standard should be kept as it is or changed.

The final decision will be a political one, but Pope said science will guide it.