Odor control in restrooms usually is pretty simple — it’s easy to tell where the odor is coming from. But odors from places other than the washroom aren’t quite as straightforward.

Some odors come from outside the facility and thus can’t be cleaned up. For example, paper mills dot northern Wisconsin’s landscape, and the smell often seeps into buildings.

“Masking is what you do,” says Lee Fahrenkrug, president and owner of First Choice Cleaning Service, Inc. in Oshkosh, Wis. He recommends having a counteracting element circulating in the air system.

But for those odors within the building, building service contractors will need to play detective in order to determine the origins and remediation strategies.

For instance, a carpet odor can be caused by a lingering food spill. Biological enzymes can help make short work of the stain and the smell. But, if the odor returns, it could be more serious.

“Usually it’s a moisture problem,” says Randy Rowley, general manager, janitorial division for Commercial Property Maintenance in Everett, Wash. A source of continual moisture — a crack in the concrete or subflooring, for instance — should be uncovered and fixed before any carpet is patched or replaced, he adds.

Unfortunately, sleuthing out an odor source can sometimes require more than a good nose — it often warrants a strong stomach as well.

“A customer was asking about a smell in the janitor’s closet,” says Fahrenkrug.”I first thought it was probably a dirty mop.”

A janitor confirmed that the mop was not the problem, and described the odor as “a rotten, dead animal smell.” The cleaner eventually (literally) sniffed out the culprit — sewer gasses were escaping through the floor drain. If a drain isn’t used frequently, the water in the gooseneck of the pipe evaporates, leaving no barrier between the air that’s breathed and the sewers. Fahrenkrug remedied the situation by pouring a gallon of bleach down the drain, followed by several buckets of tap water.

To maintain the air quality, his cleaners now flush the drain one a month and ensure the gooseneck is full and performing its odor-control function.

Proper pipe and drain maintenance also is key in the kitchen. Grease can greatly restrict flow in sink drains and pipes, causing bacteria to cling and create foul smells. Clearing the drains should help, but if you must use a counteractant in a kitchen, use an appropriate scent, Ramsey says. A “restroomy” scent might interfere with the food.

Overall, it’s important for BSCs to pay attention to odors, because they could signal a bigger problem. A savvy BSC with a good nose can help facility managers protect their investments.

Lori Veit is a business writer in Madison, Wis., and a frequent contributor to Contracting Profits.