Allowing electronic smoking in the workplace would seem to have some advantages. Some e-cigarette users who are permitted to smoke electronically at their desks claim increased levels of productivity, as they are no longer taking breaks to walk outside and smoke a traditional cigarette.

And there's also the argument that vapor inhalation isn't as damaging to the body as smoke inhalation, so some employers might believe that allowing e-cigarette use would prompt workers to make a "healthier" choice.

It's a complicated issue, in part because there isn't much scientific research regarding the potential risks of electronic smoking, and in part because e-cigarettes as a product are difficult to classify.

"One of the problems with electronic smoking is that no one understands what it is," Mackender notes. "Is it smoking, or can it be considered smoking cessation? Is it more like smoking, or is it more like a nicotine patch? And there's still research being done – what will that research say about how e-cigarettes affect people who are in close proximity to the user?"

Read: The pulse of preventative care

Mackender suggests businesses begin to evaluate their tobacco-use policy by first examining the state and local laws that might govern the use of e-cigarettes.

"There are a number of states and municipalities that have either lumped e-cigarette use into their smoking bans or have implemented new laws that prohibit the use of e-cigarettes in the workplace or other indoor spaces," he explains. "So in some jurisdictions, allowing the use of e-cigarettes in the workplace would be unlawful."

After ascertaining the state and local environment, employers will want to consider their workspace layout and how allowing e-cigarettes would affect non-smoking employees.

"Employers might have potential issues with other employees having some kind of reaction to the e-cigarette byproduct," Mackender says. "E-cigarettes are odorless, and they obviously don't generate smoke – it's a vapor – but there are still some byproducts, and other employees could have a reaction to that. And that could potentially rise to the level of a condition that could require a reasonable accommodation under the Americans with Disabilities Act."

The third facet of the issue that businesses will want to consider when looking at their policies is perception.

"E-cigarette use still looks an awful lot like smoking," Mackender notes. "Are there concerns about public-facing positions in the workplace?" Employers must ask themselves these questions and align their answers with their key business interests, whether that's a healthier workforce or a clean public image.

Mackender adds that the completion of the tobacco-use policy isn't the final step in the process.

"Employers need to keep an eye on whether there are new laws that come into effect or new research that would affect their policies," he adds, "or changes in their insurance plans that could affect their policies. And employers also need to think about the rights of the users of e-cigarettes. Some states have statutes that prohibit discrimination based on lawful off-duty activities. Using an e-cigarette in the workplace isn't an off-duty activity — but are there other considerations and rights that could come into play, and that need to be taken into account?

"At this point, there are more questions than answers," he continues. "Unfortunately, this isn't one of those situations where it's easy to plug in a policy."