MONTEREY (CBS SF) — A wildfire in Monterey County has led organizers to cancel the Salinas Valley Half Marathon this weekend over air quality concerns, race officials have announced.

The half-marathon was set for Saturday morning, but smoke from the extensive Soberanes Fire has led to unhealthy air quality on the race course, race officials said.

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“It is with regret that we announce this cancellation,” said Doug Thurston, executive director of the Big Sur International Marathon, which is the parent organization for the half-marathon.

“However, our first commitment is always to the health and safety of our runners and volunteers,” Thurston said.

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Anyone registered to the half-marathon can defer their entry to next year’s event or attend the Big Sur Half Marathon on Monterey Bay in November, race officials said.

Water, food and other supplies will be given to firefighters working to extinguish the blaze.

The Soberanes Fire has burned through 51,000 acres and was 27 percent contained.

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The blaze started on July 22 in Soberanes Creek at Garrapata State Park and was caused by an illegal campfire left abandoned, according to Cal Fire.