The Wall Street Journal recently took a random sample of air quality at hotels.
Armed with petri dishes, Journal reporters spent two nights at nine hotels and placed dishes at three locations in each room - by the air conditioner, by the window, and in the bathroom.
The Journal then hired an accredited lab to count bacteria and mold growth in the dishes.
The results? Four of nine hotels has higher bacteria counts in at least one dish than what the Journal's lab says you'd find in a typical surburban home. Mold counts were high too, high enough
that allergy sufferers might notice in for of the hotels.
The lab results also showed that air quality isn't necessarily any better in luxury hotels; on some dishes, mid-range hotel scored about as well as or better than the ritzy Delano in Miami or the
Four Seasons in Seattle.
Older hotels didn't have higher counts either, including Chicago's 79-year-old Drake Hotel, which had the lowest numbers overall.
And don't assume mold is more of a problem in hotels in humid cities: Houston's Hyatt Regency had the third-lowest mold count.
Not that the hotels agreed with the Journal's conclusions.
At the Sheraton Newark Airport, a spokesman said mold has "never been a problem" despite growth found by the Journal. And Holiday Inn, calling the experiment "too simple and incomplete," conducted
its own tests, finding its bacteria and fungi levels "would not be anticipated to cause adverse health effects in normal, healthy individuals."
Indeed, some scientists interviewed by the Journal disagreed over what levels of mold and bacteria constitute a health hazard.
Though most travelers never experience any problems, a surprising number of guests say they feel worse when they wake up.
The typical symptoms: "Sore throat, headaches, burning eyes," describes Christine Oliver, an environmental physician at Harvard Medical School, who specializes in treating patients with mold
allergies and chemical sensitivities.
Spending one night in a hotel, Oliver says, obviously isn't a matter of life or death - "but it's the kind of thing that can make you miserable that night."
Hotels steadily circulate a certain amount of fresh air inside based on the number of guests. Even though all air is screened through filters, everything from common molds to bacteria can seep or
stay in, hiding behind wallpaper or in cooling systems.
Then there are "volatile organic compounds" - a broad category including everything from room cleaning solvents to fumes from new carpets and furniture.
What's more, many hotels also use ozone-generated devices that cloak smoke and musty smells - but leave other contaminants.
Nationwide, as many as 50 million Americans - about 20 percent of the population - suffer from allergies, according to the National Institutes of Health; closely related, asthma rates have nearly
doubled since 1980, now afflicting more than 15 million Americans.
"It's a no-brainer," he says, "Vinyl doesn't breathe."