George Bush promised Wednesday to solve the acid rain problem by reducing emissions by the year 2000 and declared "I am an environmentalist, always have been." Aides to Michael Dukakis said they would use Bush's selection of Dan Quayle as his running mate to question the Republican nominee's judgment.

Dukakis campaign manager Susan Estrich said the Democratic National Committee and the campaign were preparing separate advertising campaigns to kick off the fall campaign after Labor Day. Among the campaign's targets: the choice of the Indiana senator for the GOP ticket."Dan Quayle is going to emerge not only as an issue, but as a liability on the Republican side because it goes to judgment and it goes to leadership," Estrich said at a briefing.

Dukakis, the Democratic nominee, raised questions about Bush's leadership ability on Tuesday in resurrecting the Iran-Contra scandal, asking, "How can you possibly sit there and do nothing while we traded arms to a terrorist nation?"

Dukakis campaign chairman Paul Brountas said on "CBS This Morning" Wednesday that Bush has yet to explain his role in the arms-for-hostages deal.

The vice president, who turned his attention to the environment during a brief campaign stop alongside Lake Erie near Detroit, proposed several cleanup measures as well as a global conference on the issue.

"The time for study alone has passed. As president I will ask for a program to cut millions of tons of sulfur dioxide emissions by the year 2000 and to significantly reduce nitrogen oxide emissions as well."

Aides traveling with Bush described his pledge as a step beyond Reagan administration policy.

Quayle, meanwhile, traveled to Louisiana with his wife, Marilyn, as part of a five-state southern swing.

On Tuesday, Bush ridiculed Dukakis' snowblower - the prized emblem of the Democratic presidential nominee's budget-consciousness - during one of several appearances in which he continued to criticize Dukakis as weak on defense.

"If he doesn't want to modernize his snowblower, that's his concern," Bush said at Fort Campbell, Ky., referring to the 25-year-old snowblower that figured prominently in a film about Dukakis at the Democratic National Convention. "But if he doesn't modernize our weapons systems, that puts the national security in considerable risk."