As president and CEO of Pacific Research Institute, I found that the April 22 story, "Earth Day founder remains active," painted a rather pessimistic view of environmental trends. In fact, air quality has improved in cities across the United States.

One reason is that cars and trucks are producing fewer smog-causing volatile organic compounds. These vehicle-produced VOCs fell by 74 percent between 1970 and 2003, according to the Environmental Protection Agency. Total carbon-monoxide emissions produced by cars and trucks fell by 64 percent over the same period.

Water quality is showing improvement, too. An EPA assessment covering 5,000 lakes and 72,000 miles of rivers and streams in the Eastern states found a substantial lowering of acidity. Water acidity was a chief target of the 1990 Clean Air Act Amendments.

Environmental problems, of course, are global by their very nature. So even if we're breathing cleaner air at home, we won't be doing so for long if the rest of the world is moving in the opposite direction. So it's important that we continue to encourage countries like China which is rapidly industrializing to help protect our common planet.

If we do so, Earth Day will continue to be a day of celebration, not of worry.

Sally C. Pipes
San Francisco