Smog Alerts Declared in Moorpark, Simi Valley

For the first time in nearly two years in Ventura County, officials Friday issued a health advisory in Simi Valley and Moorpark warning residents to stay inside because of high levels of air pollution.

Additionally, Simi’s 100,000-plus residents had more reason to seek relief: The city set a record temperature for Friday’s date of 103 degrees. The old record of 99 degrees was recorded in 1979, weather forecasters said.

The health advisory was issued about noon after meteorologists at the county’s Air Pollution Control District saw that ozone levels were rising and would exceed the minimum level at which a health warning is mandated.

Friday’s health advisory ended at 6 p.m.

The federal Environmental Protection Agency requires air districts to issue a health advisory when the pollutant standard index, known as the PSI, exceeds 138, district meteorologist Mallory Ham said.

“Above 100 is considered unhealthy,” he said.

By 4:30 p.m., the PSI in Simi Valley and Moorpark had reached 153, he said. The next closest PSIs were 104 in the Conejo Valley and 98 in Ojai.

The last time a county PSI topped 138 was Aug. 30, 1996, in Simi Valley and Moorpark. The last time a PSI equaled or topped 153 was in 1995, Ham said.

Pollution experts say heat contributes to dirty air.

The way Ham explained it, dirty air from the San Fernando Valley area flowed into Simi Valley with the help of low-level winds mixed with a high-pressure system. High-pressure areas are associated with higher temperatures, he said.

A high-pressure area can create an inversion that will trap the polluted air near the surface of a valley for several hours.

Ham said there was a slight possibility of another health advisory in Simi Valley and Moorpark today. As of 8:30 p.m. Friday, the air pollution control district had forecast a PSI in Simi Valley of 120 today.

The high temperature in Simi Valley and Thousand Oaks was expected to reach 96 today and 94 Sunday, National Weather Service weather specialist Bill Hoffer said.

Temperatures in Ojai will top 100 degrees throughout the weekend, Hoffer said. Oxnard and other coastal communities will see morning low clouds, hazy sunshine and highs in the 80s.