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?

Chemical intolerance contributes to the illnesses of 1 in 5 patients but the condition seldom figures in their diagnosis, according to clinical research published July 9 in the journal Annals of Family Medicine.

(Note: I was a co-author of the paper, which is available from the Annals of Family Medicine website. The study struck a national nerve, and it has been reported widely in the news media, including highly-read Medscape.com, which ran an excellent account. You’ll need a free Medscape login and password to view it. Other accounts are published at Science Daily and Fox News.)

Here’s a summary sent to the media:

Chemical intolerance contributes to the illnesses of 1 in 5 patients but the condition seldom figures in their diagnosis, according to clinical research published July 9 in the journal Annals of Family Medicine.

Clinical tools are available to identify chemical intolerance but health care practitioners may not be using them, said lead author Dr. David Katerndahl, professor of family and community medicine at the University of Texas Health Science Center at San Antonio.

The study’s authors said physicians need to know how chemical intolerance affects certain people and understand that conventional therapies can be ineffective. Some patients would improve by avoiding certain chemicals, foods and even medical prescriptions, the authors said.

Patients with chemical intolerance go to the doctor more than others, are prone to having multi-system symptoms and are more apt to have to quit their job due to physical impairment, the authors said.

The study involved 400 patients who gave personal health information while waiting to be seen at primary care clinics in San Antonio. The researchers asked the patients to respond to 90 questions about their illnesses, mental health and ability to function.

In the end, the authors said, 20.3 percent of the patients questioned met the scientific criteria for chemical intolerance.

Researchers surveyed patients with chronic conditions such as allergies, asthma, diabetes and heart disease. They excluded patients who were at the clinics for acute conditions such as earaches, flu or bone fractures.

The origins of chemical intolerance have been the subject of much speculation, the authors acknowledge, but the condition is also understudied. People with chemical intolerance, or “CI,” are highly sensitive to common substances such as cleaning products, tobacco smoke, fragrances, pesticides, new carpet and auto exhaust.

“Apart from the debate over causality, the fact that so many patients meet the criteria for chemical intolerance holds particular relevance for primary care providers,” said Dr. Katerndahl.

Chemically intolerant individuals often have symptoms that affect multiple organ systems simultaneously, especially the nervous system. Symptoms commonly include fatigue, changes in mood, difficulty thinking and digestive problems.

Study co-authors are Dr. Claudia S. Miller, professor in environmental and occupational medicine, vice chair of family and community medicine, and director of the South Texas Environmental Education and Research (STEER) Program, among her roles; Dr. Raymond F. Palmer, associate professor of family and community medicine at the University of Texas Health Science Center at San Antonio; and Dr. Iris R. Bell, professor emeritus in the Department of Family and Community Medicine at the University of Arizona College of Medicine and research professor in the College of Nursing at the University of Arizona.

An added comment: Healthcare professionals as well as the public can assess chemical, food, drug and other intolerances using the QEESI, the Quick Environmental Exposure and Sensitivity Inventory, which I developed. It is available free for download.