Mount Marathon Race officials will decide Thursday morning whether to cancel the junior race, which is scheduled for 9 a.m.

The National Weather Service is forecasting widespread smoke for Seward on Thursday, mainly before 10 a.m. The Centers for Disease Control and Prevention says children, teenagers, older adults and those who have heart or lung diseases are more susceptible to the health threats due to smoke.

The women’s and men’s races are happening, though all competitors may choose to defer entry to 2020.

Junior racers also may defer entry, but race officials are taking a more cautious approach with that race, which has not been canceled since it began in 1964. The junior race goes halfway up and down the 3,022-foot mountain overlooking Seward.

Air quality will be accessed at 7:30 a.m. and if the air is unhealthy, officials could announce via public address, volunteers at Race Headquarters and mmr.seward.com that the race is canceled by 8 a.m.

A second assessment will be done at 8:30 a.m., with final determination at 8:45 a.m.

If the junior race is canceled, racers get their $25 entry fee back and entry into the 2020 race.

For more information, check mmr.seward.com.