Chemically intolerant patients have for years moved from cities and other pollution sources, e.g., locations that burn wood to heat homes in winter, like parts of the Pacific Northwest, because of air pollution.

Where is the nation’s worst particulate pollution? In 2011, the American Lung Association published a list: 1. Bakersfield-Delano, Calif. 2. Fresno-Madera, Calif. 3. Pittsburgh-New Castle, Pa. 4. Los Angeles-Long Beach-Riverside, Calif. 5. Salt Lake City-Ogden-Clearfield, Utah 6. Provo-Orem, Utah 7. Visalia-Porterville, Calif. 8. Birmingham-Hoover-Cullman, Ala. 9. (tie) Hanford-Corcoran, Calif.; Logan, Utah; Sacramento-Yuba City, Calif.

Smog cloaks Salt Lake City’s skyline in 2011. (Photo: U.S. Environmental Protection Agency)

But this is new: Now couples are being advised to avoid air pollution when they try to conceive a baby. See the Salt Lake Tribune story “Docs: Wait - or get out of Utah’s bad air - to conceive.”

Cities in Utah endure days and even weeks of concentrated air pollution created by temporary atmospheric inversions. Common in winter, inversions trap air pollution close to the ground and push it to unhealthy levels. Utah is not alone. Los Angeles and Pittsburgh live with an even higher risk according to the American Lung Association.

If concentrated pollution can endanger a fetus, think about its overall threat to public health.

Exposures like those in Utah have the potential to initiate TILT, or Toxicant-induced Loss of Tolerance — the two-step disease process that is affecting growing numbers of people in the United States and abroad. Unfortunately, these people may not recognize their illness because of “masking.” Masking? Think of a frog placed in boiling water. Legend has it that the frog immediately jumps out, but if the water is slowly heated, the frog remains and boils to death. He adapts but to his detriment, even demise.

Masking is why we need doctors to screen patients with the QEESI, or Quick Environmental Exposure and Sensitivity Inventory, a medical questionnaire to detect loss of tolerance. And the rise in TILT shows the need for EMUs, or environmental medical units, to isolate the masking elements in patients. Then we can begin to “see” what these exposures are doing to us. The QEESI and EMU are important modern-day tools much like the microscope and physician Robert Koch’s 19th-century postulates, which helped “prove” the germ theory a century ago.

Salt Lake City is rightfully concerned about a new study in the journal Environmental Health Perspectives. It showed the risk of having a baby of low birth weight jumps 10 percent in areas with higher concentrations of particulate matter, including PM2.5. That’s the pollution that spikes in winter inversions and leads to Utah’s pollution. Ultrafine particles easily enter human airways and can travel through the nose to the brain’s limbic system, which regulates mood, behavior, short-term memory and a host cognitive functions.

There are no good choices to avoid the inversion threat, but inaction is the worst of them.

Are we going to become like China, where wealthier individuals equip their cars and homes with sophisticated air filtration devices? Where children wear masks in cities to filter air? What about the vast majority of families who cannot afford this?

Dr. Nicholas Ashford, my co-author of the book Chemical Exposures: Low Levels and High Stakes, presented a thought-provoking analogy about how the same chemical exposure can affect people differently. His comments came at a National Academy of Sciences workshop in April 2012. I presented at the same workshop on TILT, or Toxicant-induced Loss of Tolerance; the QEESI, or Quick Environmental Exposure and Sensitivity Inventory; and the need for EMUs, or environmental medical units.

Here are Dr. Ashford’s remarks:

“Let me ask you to do a thought experiment. Suppose there were 10 Apple computers lined up along that front table and I were to open the motherboards of all those computers. Now suppose I were to take 10 pairs of those little Scottie magnets that your kids play with and I threw a pair of magnets into the motherboards of all 10 computers and then closed the computers and asked the first computer to add 2 and 2 and it gives me ‘minus 5.’ Then I asked the second computer how much is 2 and 2 and it says, ‘Well over 3.’ The third one just whirs. The fourth one doesn’t do anything, and so on, for each computer, down the line.

“Now if we had computer epidemiologists they would look at these 10 computers and they’d say they are all sick and each appears to have a different disease, i.e., each gives a different wrong answer to the question how much is 2 plus 2. If the epidemiologists didn’t see me throw the Scottie magnets into the computer, they would say these are unrelated diseases. Not only that, but the incidence of the malfunction — each rendition of a wrong, but different answer to the question how much is 2 plus 2 — would not be significant enough to say there was any disease in the population at all because not enough of the computers gave the same wrong answer. That’s what we’ve got with brain-mediated, brain-damage disease and I would argue that one of the bases for Toxicant-induced Loss of Tolerance is brain-mediated damage.

“When you throw a neurotoxic chemical into the brain, and you know a lot of them get into the brain, including the limbic system, which is where the immune system, the nervous system, and endocrine system converge, they may make the brain misbehave in a number of different ways. One of the ways in which it may misbehave may be endocrine disruption. Another way that it may misbehave is attention deficit hyperactivity disorder (ADHD). A third way in which it may misbehave is that autism can develop.

“Now I said it was a thought experiment, but probably the organ we know the least about and which is computer central to our entire existence is our brain. Toxicant-induced Loss of Tolerance can manifest in a number of seemingly unrelated ways, unexplained by classical toxicology that assumes a one-hit or single insult resulting in a single kind of pathology.”

Fragrances are among the most frequent and potent symptom triggers for people who report developing chemical intolerances following an acute or chronic exposure such as to pesticides or indoor air pollutants. Sometimes specific formulations (air fresheners, fabric softeners, etc.) or brands are especially problematic, with individuals reporting headaches, impaired concentration, confusion, sudden mood changes, fatigue, etc.

Anne Steinemann at the University of Washington and her colleagues recently analyzed 25 top-selling fragranced consumer products. The paper, which can be accessed here, is an eye-opener. Using GC/MS (gas chromatography/mass spectrometry), Steinemann found that these products contain an average of 17 chemicals each, almost all of which do not appear on any label, and many of which are known to be toxic. A single fragrance may contain 100 or more VOCs. This strongly suggests that we need to find unscented alternatives for cleaning our homes, our laundry and ourselves.

Q: Why don’t the names of these chemicals at least appear on the product labels? A: Manufacturers are not required to disclose fragrances in cleaning supplies, air fresheners or laundry products. These are regulated by the Consumer Product Safety Commission. Likewise, the Food and Drug Administration, which regulates personal care products, does not require listing of ingredients used in fragrances, “even though a single “fragrance” in a product can be a mixture of up to several hundred ingredients.” Ms. Emily Sohn, writer for Discovery News, asked me to comment on the significance of this new study. Read the article here.

As an allergist, I know that individuals’ responses to exposures vary widely. The problem is, we can’t know a priori whether or in whom a scent is going to cause nasal congestion, a headache or impair the ability to concentrate-at home, at work, at school or while driving. We do know that a sizable percentage of the population responds adversely to various fragrances and other low-level exposures.

Fortunately, there is something we can do. We can stop buying fragranced products, instead choosing those that are clearly labeled “fragrance-free.” Tell the managers at places you and your family frequent, from the grocery store to restaurants to your child’s school, that you want fragrance-free products used because of the hazardous chemicals found in many fragranced products. There is no way to know how toxic a specific fragranced product may actually be, and as Steinemann found, simply choosing products that are “green” or “natural” is no guarantee of their safety. Fragranced “green” products, she reported, also emitted volatile organic compounds (VOCs) which can irritate the airways and cause multi-system symptoms in susceptible individuals.

Individuals with chemical intolerances can benefit greatly from fragrance-free policies at school or work and from eliminating fragrances at home. Unfortunately, while fragrance-free policies can help protect building occupants and custodial staff from harmful chemicals, one of the greatest sources of fragrances indoors is other people. Many people start off their day by applying a variety of fragranced products, which then volatilize into the air throughout the day. This personal “out-gassing” is worst in the morning, and it can be debilitating for chemically intolerant individuals if they must start their day sitting next to someone at a meeting or in class, inhaling complex mixtures from fabric softeners, personal care products, and cologne.

Fragrance intolerance may be an important sentinel symptom for Toxicant-induced Loss of Tolerance (TILT). There is a close anatomical relationship between the nose and the limbic (mood and memory) part of the brain. People tend to notice when a fragrance that was once loved now makes them feel ill. In my work with Gulf War I veterans, I met a soldier who sent his spouse their favorite fragrance while still he was overseas. After he returned from Iraq, she went to pick him up from the airport wearing that special scent. During the several-hour drive back home, he became so sick that he begged her never to wear it again.

I firmly believe that “Your right to wear fragrance ends at my nose,” a phrase adapted from the days when smoking indoors was still common. But, regardless of who is right, the best strategy when seated next to a heavily fragranced person is to move. It is tiresome to feel you are “on the run,” from invisible vapors of fragrance, but as more people gently explain that fragrance causes headaches, asthma, burning eyes, or nausea, perhaps both policies and personal choices will change.

One woman I know has recently been trying a new approach. When she sits next to individuals who aren’t wearing discernible fragrances, she thanks them, saying, “I want to thank you for not wearing fragrance. I often have to get up and move because other people’s perfume and laundry products can give me a headache.”

It’s a great conversation starter.

Remember: Fresh air is the best air freshener, and the best smell is no smell!