Since the first Earth Day 25 years ago Saturday, Americans have gotten a lot ''greener'' in their attitude toward the environment.
''We weren't aware at that time that there even was an environment, let alone that there was a problem with it,'' says Bruce Anderson, president of Earth Day USA, national coordinating headquarters for activities going on across the country this week.
But what began as a blip on the screen of public affairs -- the domain of a relative handful of conservationists, natural scientists, and occasional Jeremiahs like ''Silent Spring'' author Rachel Carson -- has grown into a full-fledged social movement. Business executives, educators, politicians, religious leaders, and millions of grass-roots Americans are involved.
''The support, the understanding, the concern has increased many, many times,'' says Gaylord Nelson, the former governor and United States senator from Wisconsin who thought up the first Earth Day in 1970.
And what has been the result of all this activism and the consequent legislation pushed by Republican and Democratic administrations and lawmakers? According to US government reports:
* Hydrocarbon emissions from motor vehicles have dropped from 10.3 million tons a year to 5.5 million tons.
* The number of metropolitan areas violating air standards for carbon monoxide has declined from 40 to nine.
* The phaseout of leaded gasoline has reduced the release of lead into the air by 98 percent.
* The quantity of toxic chemicals spilling into the air and water from factories and other industrial sources has declined 43 percent.
* With passage of the California Desert Protection Act last year, the national wilderness system now totals more than 100 million acres.
* The American alligator and the California gray whale have been removed from the endangered-species list, and the bald eagle -- the American symbol that once faced extinction -- is making a healthy comeback.
Despite serious issues that remain, the world is ''a safer and healthier place,'' says Environmental Protection Agency (EPA) administrator Carol Browner.
''We banned dangerous and widely used pesticides like DDT and helped to make recycling a household habit,'' she says. ''We reduced toxic air emissions and established fuel standards for automobiles. We established strong public-health standards for drinking water and eliminated direct dumping of raw sewage into our rivers, lakes, and streams.''
A kind of ''green thinking'' has become part of policies and practices. Conservation measures passed as part of the 1985 farm bill have helped reduce soil erosion on farmland by 63 percent. Uncle Sam now requires federal agencies to buy writing and printing paper with 20 percent recycled content.
Businesses have been responding as well.
Analysts at Price Waterhouse reported recently that 40 percent of the companies it surveyed have elevated oversight of environmental compliance to their board of directors. That's nearly twice as many as in 1992 and three times the figure for 1990.
Seventy-three percent of companies surveyed by Price Waterhouse now conduct environmental audits -- up from 40 percent in 1992. And 38 percent are factoring environmental performance into incentive compensation for executives and managers.
Much of the improvement has come at the grass roots. There were 600 community recycling programs in 1988; today, there are about 6,600. EPA reports that 22 percent of all municipal solid waste was recovered for recycling or composting in 1993 - up from 17 percent in 1990. Last year, there was such a shortage of recyclables that market prices in some places jumped 200 percent. Advanced-technology lights, motors, and building designs have helped save a lot of energy and therefore prevented pollution.
''Since 1979 this country has gotten about 4-1/2 times as much new energy from savings as from all net increases in energy supply put together,'' says Amory Lovins, energy expert at the Rocky Mountain Institute in Colorado. He refers to such savings as ''negawatts.''
''You can now save twice as much electricity as you could five years ago at only a third the cost,'' Mr. Lovins told the Campus Earth Summit at Yale University last year.
Twenty-five years ago, there were hardly any environmental education programs. Today, it's hard to find a public school, university, or law school that does not have an environmental program.
All students at Oberlin College in Ohio take a course titled ''Environment and Society.'' Last year, when the Chicago Board of Trade held its annual auction for ''pollution emission allowances,'' University of Maryland law students bought and retired a ton of sulfur dioxide. Students at the Walker Elementary School in Ashland, Ore., have been landscaping their schoolyard using drought-resistant native plants -- and learning about their ecosystem.
''I'm absolutely delighted and astonished at how rapidly environmental education has grown in this country,'' says Mr. Nelson, now a counselor to the Wilderness Society, who spends much of his time talking with students. ''That's the most important thing that has happened since 1970.''
Since 1989, the number of environmental groups on US campuses has grown from fewer than 50 to more than 2,000. And campuses themselves are greening up. ''Yale's switch from incandescent to fluorescent lighting will save the university $3.5 million over the next decade,'' says Teresa Heinz, chairman of the Heinz Family Foundation, which funds pro-environment efforts. ''Converting a single introductory chemistry course to microscale [smaller quantities] has helped the University of Arizona eliminate 3,600 gallons of hazardous waste and save over $12,000 in disposal costs.''
But for all the improvement, there are sobering trends and statistics as well. The National Priorities List of Superfund sites includes more than 1,200 that pose a direct threat to public health. ''Toxic contamination problems are not in our past but in our present and future,'' warns Joanna Underwood, president of INFORM, a New York-based research organization.
The biggest cleanup could be nuclear-weapons production facilities left from the cold war. The US Department of Energy this month announced the likely price tag: between $230 billion and $350 billion.
Increases in motor vehicles and highway miles traveled have largely offset gains from fuel efficiency and cleaner engines. On the first Earth Day, there were 108 million vehicles in the US. Today, the number is closer to 200 million, and the number of miles Americans travel annually has nearly doubled -- to more than 2 trillion.
Thanks to conservation and greater efficiency, per-capita use of energy has gone down. But because of population increases, total energy use in this country has grown from 66 quadrillion British thermal units in 1970 to about 83 ''quads'' today. For the first time, the US last year imported more than half its petroleum.
There are 60 million more Americans than on the first Earth Day, and the rate of consumption has not abated. This means that even with all the recycling, water-saving toilets, and energy-efficient light bulbs, the impact on the earth continues to increase.
''We use twice as much energy and generate more than twice as much garbage as the average European -- and 500 times as much as the average Ethiopian,'' says Donella Meadows, a systems analyst and author who studies resource-use, consumption, and population.
''We have more shopping centers than high schools, and we spend more time in them by far than we spend in churches, temples, mosques, and synagogues.''
While generally pessimistic about environmental trends, Dr. Meadows says one ''very good sign'' is the degree to which ecology is becoming part of economic thinking. This means that policymakers are starting to gauge the cost of environmental destruction as well as the comforts and profits derived from extracting resources. ''Until we do that,'' she says, ''nothing else will change.''