The first thing you notice upon approaching Alderwood Mall is the smell. It hits you before you even open the door, and quickly envelops your entire being. Once inside, the olfactory assault comes at you from all angles: the baking brown sugar emanating from Mrs. Fields Cookies, the warm bready pretzels arising from Auntie Anne's, the cinnamony sweetness wafting out from Yankee Candle. This is no accident.

Retailers are increasingly using scents as a way to entice customers into their stores. An article earlier this year in the Wall Street Journal noted that the fragrances that businesses diffuse through heating and air-conditioning vents have become key elements of those businesses' brands. Even hotels, apartment buildings, hospitals, and gyms have gotten into the "scent marketing" game.

Many of these scents are produced by ScentAir, a Charlotte, North Carolina–based company that claims to be "the largest and most experienced scent provider," operating in 105 countries with more than 40,000 "deployments." Phone calls and e-mails to ScentAir weren't returned, but its website details the emotional value embedded in fragrances. "When your customers smell something, the information goes directly to the 'I'm so glad I'm here' side [of the brain], where emotions take place," it states. "It's not just emotion that makes scent powerful. It's closely tied to your customers' memories, as well... By targeting the senses, brands establish a stronger and enduring emotional connection with their consumers." According to ScentAir, manufactured scents can subliminally transmit such specific feelings as relaxation, exhilaration, sensuality, happiness, and personal fulfillment.

Some people, however, find them repugnant. "To me, it smells like fecal matter mixed with cologne," said 17-year-old high-school student Brian Wiens on a recent Friday afternoon at Alderwood Mall, after walking past Abercrombie & Fitch. "Obviously that's an exaggeration, but why are you making the scent so strong?... It's unbearable."

A 56-year-old music teacher who wanted to go by only her first name, Kristi, had a similarly negative reaction to the pungent smells coming from Bath & Body Works. "It's too much," she said. "I wouldn't even go in there."

I could find only one shopper, 20-year-old Edmonds Community College student Weng Si Ieong, who liked the overpowering cologne-ish scent at Abercrombie & Fitch. She described it as "fresh" and said it made her want to shop there.

That might not be an accident, either. One study cited by ScentAir's website notes the gender differences in olfaction—that women are more sensitive to certain odors and have greater abilities to identify scents than men. It also notes a study that found that women are attracted to androstenone, a derivative of testosterone that's present in male body odor and can smell like either urine or vanilla, depending on one's genes (according to a 2007 study published in Nature).

For some stores, the challenge is finding the sensory middle ground between strong and overwhelming. "We try not to use super-strong scents," said Claudia Kallenberger, who was working at the Alderwood location of the Body Shop, where a tea candle was burning a sweet, citrusy mixture of "Frosted Cranberry" and "Satsuma Mandarin." "That's what we burn during the holidays," she said. "That's what everyone likes."

Well, not everyone. For those who work at the mall day in and day out, fragrances can be unbearable. Wayne York-Kinder, who manages a kiosk that sells cell-phone accessories, said he asked to be transferred from his company's other kiosk that was right outside of Abercrombie & Fitch, specifically because of the store's fragrance. "Fifteen minutes into my shift, I would get a splitting headache. I couldn't focus on my job properly," he said. York-Kinder now works a few stores away from Abercrombie & Fitch, but he says even walking by it makes his eyes water and sinuses feel inflamed, "almost as if I'm having hay fever in the middle of the store." As Christmas approaches, he says the store's fragrance level seems to ramp up. "It's probably 10 times as bad as it was in late summer."

Abercrombie & Fitch declined to be interviewed for this story. Requests for comment from Alderwood Mall, the Body Shop, and two other major retailers regarding their use of fragrances also went unanswered.

Anne Steinemann conducts research on pollutant exposures and related health effects. After studying about 50 types of fragrance products, she has begun to worry about the impacts these manufactured scents may have on our health. She says fragrances are a mixture of several dozen to several hundred primarily synthetic chemicals. What's troubling is that we don't know exactly what they're made of. "There is no law in any country that requires a full disclosure of ingredients," she said. And even if we did know all of the ingredients, there's a dearth of data regarding the toxicity of the chemicals both individually and in combination with others. "The industry says they're at low levels. But low levels add up. And low levels can still have impacts."

In 2010, the International Fragrance Association, in an effort to increase transparency, published a list of some 3,000 ingredients used in fragrance compounds. Among them are styrene and diethyl phthalate—the former a known carcinogen and the latter a reproductive toxin, according to Alexandra Scranton, the director of science and research at Missoula, Montana–based Women's Voices for the Earth, which works to eliminate toxic chemicals from the environment. "Mostly it's chemicals we've never heard of," she said. But even the innocuous-sounding ingredients, such as essential oils, can be troubling, she added, because the solvents used "can be pretty dangerous."

There haven't been many studies on the health impact of fragrances. Steinemann has done two national surveys and found that approximately 30 percent of the population is sensitive to fragrances, reporting symptoms such as asthma attacks, headaches, seizures, skin problems, breathing difficulty, nausea, and gastrointestinal problems. Scranton said most of the research on fragrances has been in dermatology, which has found that between 2 and 11 percent of the population have skin reactions. "The fragrance industry says it's a small number," said Scranton, "but 8 percent [of the US population] have asthma, and that's considered an epidemic. It's a large number of people—tens of millions."

The bottom line, said Scranton, is there's a lot we don't know about fragrances. "There's a data gap, a research gap, and it's disproportionate to how many people are exposed to this," she said.

Regardless of the potential health impacts, fragrances are clearly a turnoff for some consumers. So why do so many stores continue to use them? "The malls really have to think about... how many people they're repelling," said Steinemann. "I've gotten hundreds of e-mails from people who say they can't shop at the mall because of fragrances."

In response to the backlash, some government institutions, schools, and workplaces have banned fragrances. But the mall kiosk manager, York-Kinder, said he doesn't think big retailers like Abercrombie & Fitch will change their ways. "I don't think they'd give two shits what I think," he said. In the meantime, hold your nose.