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EPA Proposes that All Areas of Puerto Rico Meet Particle Air Pollution Standard

Release Date: 06/28/2004
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(#04103) In a letter to the Governor of Puerto Rico, the U.S. Environmental Protection Agency (EPA) today agreed with the Commonwealth's assessment that all areas of Puerto Rico meet EPA's new, more stringent health-based fine particle standard. This assessment is based on levels of pollution measured from a network of monitors over the past three years. Fine particles, or PM 2.5, have been shown to cause premature mortality, aggravate asthma and other respiratory conditions and contribute to cardiovascular problems such as heart attack and arrhythmia.

"This is truly good news for the people of Puerto Rico," said Jane M. Kenny, EPA Regional Administrator. "It is important, however, that Puerto Rico maintain the progress it has made toward cleaner air. EPA is also doing its part to reduce PM 2.5 emissions."

In a February 6, 2004 letter to EPA, Puerto Rico recommended that the entire Island be designation as "attainment" with the new PM 2.5 standards. EPA is agreeing with that recommendation. The Agency will work closely with Puerto Rico to ensure that the standard continues to be met and that progress will be made in even further reducing fine particle levels.

EPA has a comprehensive air pollution control strategy that will reduce PM 2.5 pollution throughout the entire country. The Agency has already put into effect regulations dramatically reducing pollution from gasoline-powered vehicles, diesel trucks and buses. The Agency recently finalized regulations to control pollution from nonroad diesels, such as construction and farm equipment.

PM 2.5 refers to particles measuring 2.5 microns in diameter, or about 1/30th the width of a human hair. These particles can either be emitted directly as dust or soot or can form in the atmosphere. These particles have been scientifically linked to serious health effects. Their ability to be suspended in air for long periods of time and their ability to lodge in the lung makes them a public health threat. EPA first adopted new standards to regulate PM 2.5 in 1997, along with continuing to regulate particles measuring 10 microns in diameter and a new, more protective standard for ground level ozone or smog. The progress in implementing these standards was hindered by litigation. The Supreme Court upheld the standards. In 2003, all legal challenges were addressed, allowing EPA to move forward with putting the standards into action.

The Commonwealth will have at least 120 days to comment on EPA's recommendations. EPA is required to make final decisions by December 31, 2004. EPA plans to make its decision in mid November in order to meet clean air goals as soon as possible. For more information about PM 2.5 pollution and today's proposed designations, visit