Indoor Air Expert Follows His Nose
by Joe Wheeler

"Common sense and simplicity are better than rocket science in finding the source of odors," said Thomas McManus, president of Environmental Health Services, a Las Vegas based indoor air investigation and remediation company.

McManus has earned degrees in chemistry and microbiology, and is an industrial hygienist with 21 years experience in industrial hygiene and safety. In recent years, he’s become one of Nevada’s top experts in identifying and remediating indoor air problems. His company specializes in industrial health and safety issues with emphasis on occupational IAQ investigations and process chemical safety.

Thomas McManus 

He conducted a workshop for the American Indoor Air Quality Council’s on November 21. Drawing on his substantial experience in the field, he gave a "Practitioner’s Perspective" of indoor air investigations. McManus said that locating the source of foul or dangerous odors is the key to a successful remediation effort, and it starts by using one of the most sensitive detection instruments a scientist has.

His nose.

"Humans can detect about 10,000 different odors," McManus said. "To be detected, odors must be volatile, and also must be the right size and shape - they must match the receptors in the nose."

Smell is a natural part of humans, and an important part of our physiology. McManus said that babies are born with a sense of smell, and at birth don’t like the smell of fish or rotten eggs. Such a response is a natural defense mechanism against bad food and bad air.

AMIAQC Chapter President Rex Wilhoite has steadily increased attendance at area seminars over the course of the last two years.

There are only seven distinct odors detectable by a human being. They are camphor, mink, musk, floral, ether, peppermint, and pungent/putrid. All other odors are combinations of these "primary" odors. Humans can smell certain strong odors, such as green peppers, down to 100 parts per billion, but many odors cannot be detected by human beings at all. Asbestos and mineral dusts are undetectable, while many dangerous odors like methane, carbon monoxide, and nitrogen are at the threshold. Gases can be tricky, which makes the indoor air investigator’s job that much harder. Hydrogen sulphide, also called "sewer gas," can be detected at first but has a natural anesthetic property that shuts down the nose’s receptors and makes you think it has gone away. At low levels, amyl acetate smells putrid but at higher concentrations, it’s recognized as bananas.

"Things that smell bad are sometimes not toxic," McManus said. Spoiled food and bio-effluents are two examples. "And there are things that smell good that can kill you; metal hydrides, benzene or phosgene, which smells like newly mown hay."

What’s That Smell?

With extensive investigation experience, McManus has stories about many buildings in Las Vegas and their peculiar indoor air concerns.

"The City of Las Vegas had air intakes at ground level where the bus dropped off passengers," he said. "In winter, the exhaust floated right into the air intakes."

A local nightclub asked him to help get rid of cigarette smoke. He spent two days examining the problem and concluded there were more than 500 milligrams of smoke in the air, a serious amount of the noxious substance. "It was so bad, it broke my instrument," he said.

He investigated a case in which the glue in ceiling tiles caused odor problems in a two-year church in Henderson. He worked on a case in which a homeowner, who had installed a new floor, went to work to work the next day and found a terrible surprise waiting for him when he returned.

"It was a wood floor and the solvents in the floor killed his cat," McManus said. "He left it there with no air movement and the glue killed it."

A Practical Approach

McManus said that when arriving at a scene of suspected indoor air contamination, the first thing to do is a site survey. Find out the history of the problem. How long has there been the smell? Is it only during warm weather or cold weather? To do this, he’ll conduct interviews and do a visual and odor observation.

Considerations should be the time of day the offensive odor occurs, the operations of the facility at that time, and even the outside conditions during the complaint periods. All of these can be contributing factors, such as the bus creating exhaust that floated into the building.

"The best odor detection methods are a bloodhound, the human nose, and industrial hygiene instruments," he said. "The human nose is usually the most efficient tool. Follow your nose. "

He recommended sampling only when the odor identity is known or strongly suspected since the shotgun approach is the most expensive for the client.

"The idea is to identify what is in the air and where it came from," McManus said.

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