Get your facts straight about the smell
If other employees have complained to you about their colleague's odor, you'd need to investigate first. Make sure the rest of the staff don't have any ulterior motives for complaining about their counterpart (To badmouth someone that's up for the same promotion as them, or just general cruelty).
As tough as this might be- you need to actually spend some time near the smelling employee to see if it's true.
Once you've established that the smell is there you need to have the dreaded talk.
Be direct but tactful with the smelly employee
Take this quick quiz to find out if you can handle the DoL hot seat
• Which risk assessments have to be checked by an approved inspector every two years?
• Is it absolutely necessary for your company to appoint and train someone as a risk assessor?
• When was the last time you did a risk assessment? (Is that too long?)
• Have you checked and double checked the less obvious health hazards?
If you can't answer even one of these questions you're not only putting your employee's lives at risk; you're also putting yourself in danger of massive fine from the DoL.
Don't wait until it's too late.
Learn how to do your risk assessments correctly here.
Start by calling the employee in for a private meeting and address the employee hygiene. Don't ever do this in front of other employees.
Reassure the employee that it's not about her work.
Be direct. Tell her that you've noticed a particular type of odor. Let her know that it's affected other employees as they're finding it difficult to work alongside her. Say that this isn't the type of thing people realise about themselves.
Most of the time the employee will be shocked and embarrassed.
As in this situation, a straightforward conversation may be all that's needed to get offending workers to change their habits. Most workers take it upon themselves to solve, or at least minimize, the problem with more frequent bathing, clothes washing, or use of deodorant or antiperspirant.
But if it's more a cultural problem in terms of food that gives off different body smells then unfortunately you're going to have to ask the staff to be a little more accommodating.
If it's an employee smelling of alcohol then you'd need to take a harder line against them. Let them know that coming to work drunk or smelling of alcohol is completely unacceptable.