What has changed in five years?

What's been done -- and what hasn't -- since The Bee's last air-quality special report.

Air now top concern

2002: Valley residents rate expanding population and urban sprawl as the biggest issues in a Public Policy Institute of California survey.
2007: Residents rank air quality as the Valley's No. 1 issue, as indicated by surveys in 2003, 2004 and 2006.

Farms make advances

2002: Dirty diesel engines are largely unregulated on farms. Officials are just realizing dairies are a major source of air pollution.
2007: Farm and dairy pollution controls take a leading role in the Valley's air cleanup, reducing more than 85 tons of pollutants per day.

Cleanup delays continue

2002: The federal Environmental Protection Agency approves local air officials' request to enter the Valley into the worst-offender category: "extreme noncompliance for the one-hour ozone standard." The move delays the district's cleanup deadline to 2010.
2007: The EPA is expected to accept Valley air officials' request for extreme noncompliance on the newer eight-hour ozone standard. The status will delay the cleanup deadline to 2024.

Some progress for Fresno

2002: The Valley's biggest city has not been represented on the air district board since 1994.
2007: Fresno will have a permanent seat on the board starting next year.

Technology still lags

2002: State regulators shun technology known as "remote sensing," which can sniff out the worst- polluting vehicles.
2007: State air officials continue to resist the use of remote sensing, saying it would cost too much.

Childhood asthma grows

2002: About 50,000 children in Fresno County are diagnosed with asthma.
2007: About 75,000 children in Fresno County have asthma.

Some areas clean up

2002: Parlier, Clovis, Sierra Sky Park in Fresno and Arvin record the most ozone violations in the Valley.
2007: The population centers in Fresno, Bakersfield, Modesto and Stockton have recorded far fewer violations. The problem spots are Arvin and Sequoia National Park.