High Smog Prompts Health Advisory

High winds pushed unhealthful air from the San Fernando Valley into Simi Valley and surrounding areas Thursday, prompting Ventura County officials to declare a health advisory for much of the day.

Levels of ozone, an invisible irritant that impairs breathing, reached a high of 138 on the Pollutant Standard Index Thursday. Levels between 101 and 199 on the scale are considered unhealthful.

Ventura County forecasters blamed the persisting high pressure system that has been pushing temperatures up over Southern California in conjunction with winds coming out of the Los Angeles area for the high smog levels here.

Meteorologist Kent Field of the Ventura County Pollution Control District said injections of smog from the San Fernando Valley are more common late in the summer and can be blamed on unusual weather patterns over this part of the state.

A new weather system developing off the coast should help lower the smog levels, but not before the weekend, Field said.

“We still have a chance for high smog over the weekend, but the weather system that’s causing this problem is weakening,” he said.

Forecasters are predicting ozone levels at 95 on the PSI for Simi Valley today. Levels between 51 and 100 are considered moderate on the index.

Field advised that residents of the Simi Valley and surrounding areas should try to avoid strenuous outdoor activity in the afternoon when smog levels are highest.