Simi Has Its Highest Ozone Level of Year

Pollution rode into Simi Valley on southeasterly winds Tuesday afternoon, pushing air quality to the unhealthful level for the first time this year.

The wind kicked up about noon and lasted until 2 p.m., when ocean breezes from the west took over, said Kent Field, meteorologist for the Ventura County Air Pollution Control District.

“Simi got about two hours of injection from Los Angeles,” Field said. “That added to the pollution that we already had.”

After the sea breeze kicked in, the ozone level fell from a high of 119 on the pollutant standard index to 90. The federal government sets 100 on the index as the point at which the concentration of ozone pollution in the air becomes unhealthful to breathe.

Ozone is created when emissions from cars and other sources mix in sunlight.

Ozone levels in the rest of the county remained within the healthful range. But Field said they may rise with the temperatures later this week. Temperatures in inland valleys were expected to rise from the upper 80s today to the low 90s Thursday.

“Higher temperatures bring the possibility of higher pollution,” Field said.

The county is under a high-pressure zone that is trapping pollutants and keeping air stagnant near the ground, Field said. The muggy days that much of the county has experienced are the result of “monsoonal moisture” that usually lingers over Arizona this time of year, Field said.

The highest level of ozone so far this year in the county occurred May 9 when the pollutant index reached 129 at Emma Wood State Beach north of Ventura.