Venice, Louisiana (CNN) -- Seven oil spill recovery workers who were hospitalized in New Orleans after complaining of feeling ill were properly trained and had protective gear on, according to the the federal on-scene coordinator for the oil spill response effort in the Gulf of Mexico.
"The heat and humidity in Louisiana can be challenging," Coast Guard Rear Adm. Mary Landry told reporters Thursday afternoon.
She said the workers were treated for several symptoms, including headaches, nausea, vomiting and shortness of breath. Safety officials from the Coast Guard, BP and the federal Occupational Safety and Health Administration had responded to the incident, Landry.
"Basically, these folks all had the proper personal protective equipment on, and they all received the required training," she said. "Fortunately, everyone is fine."
An investigation is under way "to make sure what we can do to ensure that these workers are all working in safe conditions," Landry said. "We will continue to monitor this situation very carefully so that nobody is put in harm's way as they respond to this spill," she added.
A BP spokesman, John Curry, said the company takes "worker safety seriously." The company also said it has provided spill recovery workers with protective equipment, such as suits, steel-toed boots, gloves, hard hats and safety glasses.
In addition, BP said, workers are conducting about 250 air-quality tests a day. They also are testing workers for exposure to irritants and other substances that could be harmful, BP said.
The company also noted that testing has shown that "airborne contaminants are well within safe limits."
The seven workers were at West Jefferson Medical Center in suburban New Orleans, said spokeswoman Taslin Alfonzo said. Five were discharged Thursday afternoon, she said.
Based on their symptoms, the workers appeared to have come into contact with some type of irritant, Alfonzo said. However, the hospital doesn't have a toxicology department, so it couldn't identify the irritant.
About 10 workers complained of feeling ill on Wednesday, prompting officials to recall more than 100 boats from an area adjacent to the Mississippi River delta. Lisa Faust with the Louisiana Department of Health and Hospitals said she believes as many as five were treated at the scene.
Six of the seven were brought to the Marrero, Louisiana, hospital Wednesday night by ambulance, and the seventh was flown in. No additional patients have been admitted, Alfonzo said.
The Unified Command -- a coalition of agencies including the U.S. Coast Guard, the Department of the Interior and the National Parks Service -- said Wednesday it recalled 125 vessels from Breton Sound, which lies about 50 miles southeast of New Orleans.
The vessels were involved in cleaning up oil that has been gushing into the Gulf of Mexico since April, when an oil rig sank about 40 miles south of Louisiana, opening up a leak that has been gushing crude oil into the water.
U.S. Rep. Charlie Melancon, D-Louisiana, again called on the federal government to deploy temporary clinics to south Louisiana to screen workers and relatives possibly affected by the oil.
"As I first alerted the federal government over a week ago, our workers and residents in the oil-affected areas of south Louisiana are facing a looming health crisis," Melancon said in a written statement. "People are being exposed to hazardous oil fumes and potentially dangerous dispersants every day, and there is no health care infrastructure in place to treat them and monitor the situation."
Melancon said he will personally ask President Barack Obama to take action when Obama visits south Louisiana on Friday.