Ozone

Re "Ozone alert," editorial, March 17 Readers of The Times may have wondered if they were reading the views of the editorial board or the talking points of an environmental lobbyist. After all, both consider the U.S. Environmental Protection Agency's creation of the most stringent eight-hour standard for ozone in our nation's history an outrage only because it occurred during President Bush's term. The fact is I strengthened the ozone standard as required by the Clean Air Act and as supported by the full breadth of the most recent scientific evidence.

The ozone hole over Antarctica, caused by depletion of stratospheric ozone by man-made gases, was the fifth biggest on record, reaching a maximum area of 10.5 million square miles in September, NASA said. That's considered "moderately large," NASA atmospheric scientist Paul Newman said in a statement. NASA has tracked the size of the hole for 30 years. Last year, it was 9.7 million square miles, about the size of North America.

Ethanol, widely touted as a greenhouse-gas-cutting fuel, would have serious health effects if heavily used in cars, producing more ground-level ozone than gasoline, particularly in the Los Angeles Basin, according to a Stanford University study out today. "Ethanol is being promoted as a clean and renewable fuel that will reduce global warming and air pollution," said Mark Z.

Many areas of the United States that meet existing smog standards could be declared out of compliance under proposed new ozone levels announced Thursday by the Environmental Protection Agency. Under court order to update ozone standards for the first time in a decade, EPA administrator Stephen L. Johnson proposed tightening them slightly in response to mounting evidence of health risks.

Rising levels of ozone pollution near the ground are damaging the ability of plants to take up carbon dioxide, reducing their potential to act as a counterbalance to greenhouse gas accumulation, scientists said Wednesday. When affected by projected high levels of ozone, plants can absorb up to one-third less carbon dioxide than healthy plants, the researchers found.

A hole in the ozone layer over Antarctica has appeared earlier than usual this year, the United Nations weather agency said Tuesday. The World Meteorological Organization said it would not be clear for several weeks whether the ozone hole, which is expected to continue growing until early October, would be larger than its record size in 2006.

The California Air Resources Board on Thursday banned popular in-home ozone air purifiers, saying studies have found that they can worsen conditions such as asthma that marketers claim they help to prevent. The regulation, which the board said is the first of its kind in the nation, will require testing and certification of all types of air purifiers. Any that emit more than a tiny amount of ozone will have to be pulled from the California market.

The Antarctic ozone hole is back to an average size, shrinking about 16% from last year's record high, NASA said Friday. But it's still the size of North America. The ozone hole in mid-September reached its maximum for the year of 9.7 million square miles, down from its peak of 11.5 million square miles last year, said NASA atmospheric scientist Paul Newman. The ozone hole was discovered in 1985, and at the current rate it should be closed up by 2070, Newman said.

Earth's ozone layer is finally on the mend after decades of damage, two United Nations agencies reported Friday. But recovery has been slower than experts had hoped, the World Meteorological Organization and the U.N. Environment Program said. The ozone layer filters dangerous solar radiation. By 2049, the protective layer will be back to pre-1980 levels over huge areas in the Northern and Southern hemispheres, the agencies said.