The Occupational Safety and Health Administration (OSHA) has opened an investigation into the death of Minnesota Vikings offensive lineman Korey Stringer, 27, who died Wednesday of heat stroke after collapsing following a practice at the team's training camp in Mankato, Minn.

OSHA interviewed several Vikings employees Wednesday in Mankato. Representatives may be back at the camp as early as next week to finish their investigation, which could lead to citations and fines against the Vikings if they are found to have violated OSHA standards for workplace safety.

OSHA is still hoping to speak to some of Stringer's teammates, coaches and family members as part of their investigation. OSHA investigates anytime there is a work-related fatality.

"If it's very hot and you have high relative humidity, any work, even moderate work such as lifting and pushing, can be very dangerous," said Minnesota OSHA spokesman James Honerman. "The Vikings are cooperating fully. Based on the outcome of our investigation we could issue penalties for any violations. But right now it is far too early to even talk about that kind of thing."

In 1999, 34 workers died in the U.S. as a result of heat stress. According to OSHA, work can become dangerous when humidity reaches 60% and temperatures climb above 95 degrees. Heavy clothing, workload, and access to water and shade are all factors in heat-related illnesses.

Stringer died after working out on the hottest day of the year in Minnesota, with stifling humidity and temperatures in the 90s that drove the heat index near 110 degrees. After struggling with the conditions on Monday, Stringer vomited at least three times during practice the next day but did not contact a trainer until the workout had ended.

"Here in Minnesota we have a rule that employees have the right to know what hazards exist at their work site, how it can affect them and how they can protect themselves from it," said Honerman. "We want to see if they [the Vikings] addressed workplace hazard issues, including heat-stress issues. Our main concern is whether or not [the Vikings] got together and talked about how to prevent it and, most importantly, if staff and players had talked about or were trained in how to recognize when a co-worker is having a heat-related illness."

In a statement Wednesday NFL commissioner Paul Tagliabue said: "NFL medical staffs are extremely knowledgeable regarding the hydration of players, fluid replacement and other methods used to prevent heat stroke. However, we now will ensure that our clubs again review their policies and procedures in this area."

OSHA has a heat-stress standard that uses a heat-stress monitor and a complicated mathematical formula to calculate unsafe temperature indexes, which can then be used to shut down unsafe work sites.

"Do they have adequate water? Are they offered more breaks? Are they working in the coolest part of the day?" are some of the questions OHSA will pose to Vikings management.

"We want to make sure folks know why this happened," says Honerman. "Because that will help us prevent it in the future. Not just at this worksite but for any worksite."

David Fleming is a senior writer for ESPN The Magazine. E-mail flemfile@aol.com.