The Associated Press

FARMINGTON — Smog levels in San Juan County violated planned federal health standards for ozone air pollution, raising concerns about a third coal-fired power plant in the region.

Monitors showed an average of 77 parts per billion, exceeding a federally allowed limit of 75 parts per billion that will take effect in three years. The current standard is 80 parts per billion.

"While this violation is a wake-up call, it's also an opportunity to develop a strong, lasting cleanup plan," said Jeremy Nichols of the conservation group WildEarth Guardians.

Ozone is a key component of smog, which forms when nitrogen oxides and volatile organic compounds released from cars, industry and plants mix in sunlight. It can irritate the respiratory system, reduce lung capacity and aggravate asthma.

Nichols said to safeguard public health, the region will have to trim emissions and that means looking at the two existing coal-fired power plants, oil and gas wells and the planned Desert Rock Energy Project.

The Environmental Protection Agency issued an air permit for Desert Rock on July 31, a decision criticized by Navajo groups, state officials and environmental groups who said the decision was not well researched.

The Navajo Nation's Dine Power Authority and Houston-based Sithe Global Power are partners in the 1,500-megawatt plant southwest of Farmington. They argue the plant's pollution control mechanisms, along with reductions in emissions from the other two plants in the county, will improve air quality.

"When you talk about overall ozone, you're talking about regional haze," said Sithe spokesman Frank Maisano. "Our modeling and our controls on Desert Rock will make Desert Rock part of the solution."

Arizona Public Service operates the Four Corners Power Plant and Public Service Company of New Mexico runs the San Juan Generating Station, both located west of Farmington.

PNM spokeswoman Susan Sponar said in-progress upgrades will reduce the San Juan plant's nitrogen oxide emissions by 35 percent. She said the work should be completed next spring.

Mary Uhl, state Environment Department Air Quality Bureau director, said she had expected San Juan County to exceed the new smog standard. The state has been working on a plan to bring the county into compliance.

"We are just in the beginning of constructing a plan," Uhl said. "We had an early action compact to talk about a plan. We had known the San Juan County area is on the cusp of non-attainment."

The EPA estimates that more than 300 counties nationwide will not be able to meet the standard, although it is not expected to make official non-attainment designations until 2010.

Nichols said the air quality problem and possible solutions will be the focus of a meeting of the state Environmental Improvement Board next month. He said the state should enact additional air quality safeguards now rather than wait for the standard to take effect.

"Let's start doing something now," he said. "Let's talk about what more we can do to keep oil and gas air pollution in check and to figure out whether we need to be doing more to keep coal-fired power plant pollution in check."