A Safeway store in St. Helens was evacuated after more than 30 people experienced breathing problems, but it's still not clear what caused it.
Emergency crews were called to the store at 4:45 p.m. Wednesday.
Customers said they experienced symptoms ranging from a tickle in their throat to coughing to a bad headache. They said it all happened very quickly.
Those affected were rushed to a neighboring business to be treated by paramedics. Firefighters said 60 people were in the store at the time.
Investigators said the situation was not considered life-threatening and employees were allowed back inside at 9 p.m. The store reopened later in the evening, according to firefighters.
However, the source of the situation has not been located.
A hazmat team from Portland used sophisticated air monitoring equipment to investigate the fumes, but no source was identified following an extensive search.
A subsequent evaluation and testing effort by a refrigeration and ventilation technician also did not reveal any leaks or other sources of potential fumes or vapors, according to Columbia River Fire and Rescue.
A follow-up assessment of the store's ventilation system is planned for Thursday to ensure the entire system is functioning properly.
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