Smoke-sensitive federal workers have a stake in a case before the Merit Systems Protection Board that could set a precedent for forcing federal agencies to provide separate-but-equal working facilities for smokers and nonsmokers or ban smoking from all federal agencies.

The board will rule shortly in the case of Leroy Pletten, a 14-year employe of the Army in Warren, Mich. Pletten, a Grade 12 employe, says the Army put him on forced sick and annual leave and finally removed him from his job because he cannot work around smokers or in a building where people smoke.

Pletten said that he did not take any sick leave during his first 10 years in government, but that his exposure to tobacco smoke has aggravated his condition. His doctor agrees that Pletten must have a smoke-free environment.

After the government rejected Pletten's request for disability retirement, he took his case to the merit board. He argued that the Army was denying him a job because it refused to accommodate his handicap--intolerance to smoke. The board rejected his first appeal, but took it up again on orders of the Equal Employment Opportunity Commission, which said the Army was guilty of discrimination by not providing a smoke-free environment.

The board agreed to review his case and took the unusual step of soliciting comments from the general public over the issue of the government's obligation to handicapped workers.

Pletten's smoke sensitivity became so bad--he says he suffers even if people are smoking elsewhere in the building--that the Army placed him on involuntary sick and annual leave. His application for disability retirement was turned down.

Most federal agencies prohibit smoking in elevators, conference rooms and in portions of cafeterias. Government policy is to separate smokers and nonsmokers wherever possible, but no agency has ever issued a blanket rule. Generally speaking a smoke-free environment is an office or area where smoking is prohibited.

The issues in the Michigan case could revolutionize government policies as they relate to handicapped workers. Pletten contends (and his doctor agrees) that he cannot work in a building where smoking is permitted. Pletten and his attorneys maintain that he must either be given a completely smoke-free work environment--such as assignment to a no-smoking building--or be allowed to retire on disability.

It will be up to the board to decide what, if anything, to do in the Pletten case. The merit board is the federal agency created by the Carter administration to deal with complaints of federal workers who believe they have been fired, demoted or disciplined improperly, without just cause or for political or personal reasons unrelated to their performance. It is a bipartisan commission--two Republicans and one Democrat--all appointed by President Reagan.

The board could do several things. It could:

* Order the Army to provide a completely smoke-free environment, such as a separate building or a building with nonsmokers.

* Rule that the Army has done enough by attempting to accommodate the employe.

* Decide that the Army cannot or will not help out the employe and order him retired on disability.

* Any combination thereof, or none of the above.