Advertising: Promoting Nature's Friends

"We took most of the lead out, to help clean up the air," boasts an ad for Esso Big Plus gasoline. Another ad reads: "A new gasoline—non-leaded Shell of the Future. Part of Shell's drive for cleaner air." A third is headlined: "How do you pick the right gasoline to help fight pollution? Choose lead-free Amoco Super-Premium."

Spurred by mounting public alarm over smog-choked cities and a generally threatened ecology, the gasoline producers are dashing to establish their credentials as nature's protectors. They are not alone. Environmental control has become one of the hottest themes on Madison Avenue, and it...