State and local officials continued Friday to investigate the source of a sulfur-like odor that has plagued residents near St. Rose for much of the week.

Meanwhile, a local environmental watchdog said she has received dozens of calls from area residents complaining of feeling sick since the odor appeared.

Anne Rolfes, the founding director of the Louisiana Bucket Brigade, said she received about 35 calls at the group’s New Orleans office in the last week from people asking about the odor. She said many reported being “sick from chemical odors” and recounted symptoms like diarrhea, headaches, vomiting and asthma attacks.

Receiving that many calls over a single incident like a chemical odor is unusual, she said. “This is unprecedented, this number of calls, and I think it’s because this has gone on so long,” she said.

Crews from the Louisiana Department of Environmental Quality and the St. Charles Parish Emergency Operations Center have been investigating the odor, and they said ongoing air-quality monitoring indicates that it does not pose a health hazard to residents.

They have not recommended the public take any protective measures.

But given her recent call log, Rolfes criticized the state’s monitoring as “ineffective.”

Officials believe they’ve narrowed the odor down to two possible sources: the International-Matex Tank Terminals or a nearby Shell facility.

DEQ spokesman Tim Beckstrom said Friday that a private third-party team will be in St. Rose this weekend to monitor the air. The effort is being paid for by IMTT and Shell, he said.

“We’ve been inside the facilities, and we’re still trying to get to the bottom of it,” Beckstrom said.

Residents may call the St. Charles Emergency Operations Center at (985) 783-5050 24 hours a day for more information or to make odor reports.

Beckstrom advised residents who are feeling ill to consult a physician.

Follow Richard Thompson on Twitter, @rthompsonMSY.