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?