On Kauai, nine people went to the hospital and Walmart was shut down for a few hours after reports of a noxious odor.
Authorities are still investigating the source of the smell.
The incident was reported at about 11 a.m. Sunday.
Fire officials say the odor was confined to the main entryway but they evacuated the entire store.
The nine people were treated at Wilcox Hospital for irritation and burning of the eyes and throat.
Kauai Fire Department Hazmat crews and the state Health Department have not yet been able to find the source of the problem.
The store reopened at about 2:30 p.m.