Once again Earth Day has come around, traditionally a day of baleful prophecies. A better Earth Day activity would be review of the actual environmental record, which will lead to more upbeat activities.

Consider first the state of the air. As reported by the Environmental Protection Agency, aggregate emissions of air pollutants have declined 25 percent since 1970, notwithstanding increases of 40 percent in population, 43 percent in energy use, and 165 percent in real GDP.

Average vehicle emissions are declining ten percent per year. Since 1988 the annual number of days in the U.S. with adverse air-quality indices has declined by about 70 percent. Since 1976 concentrations of the six central air pollutants have declined between 28 and 98 percent

Between 1993 and 2002, the percentage of the U.S. population served by community water systems reporting no violations of health standards has increased from 79 percent to 94 percent. The way we collect information on water conditions could be improved, but by current accounting the improvements are significant, welcome, and at odds with media reports that still tend toward the sensational.

Since 1988 toxic releases have declined 55 percent even as output from the relevant industries has increased 40 percent. Dioxin emissions have declined 92 percent since 1987. Annual wetland losses have declined 80 percent over the last three decades.

These figures, one must repeat, are not any kind of utopian wish list. They represent actual conditions, as reported by government agencies and assembled in the Index of Leading Environmental Indicators 2004, co-published by the Pacific Research Institute and American Enterprise Institute.

This annual report shows that environmental quality is improving steadily and virtually across the board — with public lands as the exception. Private groups, as this year's Index shows, are doing a good job protecting wildlife and preserving habitat. While the overall improvements will come as news to many, none of it should be surprising.

As the late Aaron Wildavsky noted, wealthier is healthier. Individuals and societies rationally opt for greater levels of environmental quality as individual and aggregate wealth grows. It is the affluent society that does not want to be the effluent society.

It would be amazing if an increasingly wealthy and technologically advanced society failed to engender economic and political processes yielding constantly improving environmental conditions over time.

At the same time environmental quality itself is a very real form of wealth. But it is not the only form, and environmental policy always must remain cognizant of both the benefits and the costs of environmental improvement. Both the benefits and costs can be explicit and subtle.

On one hand there are cleaner air and water and improved labor productivity. On the one hand, environmental spending and the erosion of private property rights. For some, no benefit is too small to justify any given cost, regardless of magnitude. Indeed, on the fringes, actual environmental degradation is worth the acquisition of increased political power.

Draconian regulation and infringement of property rights are often sought for the benefit of "the children." But the children's prospects of a long and healthy life have seldom been better. The interest of future generations is served by the inheritance of the largest possible stock of capital, including technology levels, of which the environment itself is but one important component among many.

Based on the actual facts, Earth Day is a good time to shunt aside the standard environmental doom-and-gloom, the scare tactics, and the politicized fear-mongering. Earth Day is a time to rejoice in our society's great wealth. It should be a day to celebrate, not lament, the institutions that reward productivity and investment.

Balancing conflicting goals is not a bad definition of life. On Earth Day we can also celebrate the good sense of nation's people in assigning high value to environmental improvement.