DIAMOND BAR, CA – Preliminary findings released by the South Coast Air Quality Management District (AQMD) suggest that Southern California has again earned the distinction as the region with the worst overall air quality in the nation, reported the Los Angeles Daily News. AQMD researchers found that this year’s smog season in Southern California appears to be ending with 86 days of unhealthy air at least one measuring station. That compares to 83 days last year, and 88 days in 2004. The San Joaquin Valley came in a close second with 82, while Houston finished a distant third with 34 unhealthy smog days. Within Southern California, Santa Clarita had the fourth-most unhealthy days for a measuring station, 39, behind Banning Airport, 44, Perris, 54, and Crestline, 60. Smog season begins May 1 and ends Oct. 1. A complete report will be released this month. While automobiles run cleaner, officials with the AQMD say trucks using diesel fuel, ships at port, and trains all still contribute to unhealthy days. The AQMD is continuing to encourage the federal government to order cuts in smog-forming pollutants and fine soot in diesel exhaust from trains and ships. Researchers say the 2006 smog season peaked early because of this summer’s unusually high temperatures.