Smaller, deeper, deadlier

By John deJong

From PM10s to ultrafines, what particulate matter comes down to

From the beginning of time, humans have lived with air pollution. With the discovery of fire we began to poison ourselves and each other. The air in the cave where a saber toothed tiger had been crackling over the fire must have been rich with products of incomplete combustion and the like, but no one lived long enough for it to affect their health.

The industrial revolution was fueled with coal. The ill effects of all those smoking chimneys were generally limited to the mills and mill towns. Only the mill owners could afford to live very far from the mill.

The discovery and exploitation of oil and natural gas fueled the transportation revolution, embodied in oil-burning internal combustion engines taking pollution on the road, literally, which led to suburbs and all that they entailed.

For ages, our efforts to deal with air pollution amounted to nothing more than moving around the fire to get out of the smoke. It took advances in many sciences before we began to understand how badly we were damaging ourselves. Statistics began to play an important part in 1854 when Dr. John Snow, the son of a coal-yard laborer, traced cases of cholera in London to a public well by plotting case locations on a map. Snow is considered the father of the science of epidemiology.

Statistics continue to play an important part in understanding and relieving pollution. New studies showing the pervasive and insidious nature of particulate matter use sample sizes of millions of people over years to reach their conclusions.

Air Quality made simple

Air quality is a complicated topic. The EPA has made it simple by identifying six of the most common pollutants and setting criteria for each of them. The six criteria pollutants are lead, carbon monoxide, sulfur oxides, nitrogen oxides, ozone and particulate matter.

When lead was taken out of gasoline, it ceased to be an air quality problem. Carbon monoxide is only a problem when combustion machinery is not tuned up or operating properly. Sulfur and nitrogen oxides continue to be a problem but are fairly well understood.

Ozone and particulate matter are turning out to be much more complex. This article will focus on particulate matter. We will examine ozone in next month’s issue.

Particulate matter is the most complicated of the six criteria pollutants. It’s sort of an “everything else” category. As research progresses, it is becoming apparent that particulate matter is a super villain, a master of myriad disguises.

Utah’s role

In a very real way, the story of particulate matter started right here in Utah, in 1991, when Arden Pope, an economics professor and statistician at BYU, published the seminal report, “Respiratory hospital admissions associated with PM10 pollution in Utah, Salt Lake, and Cache Valleys” in the Archives of Environmental Health.

Research had been done on particulate matter 10 microns or smaller, but no solid evidence of a direct link between PM10s and any particular disease had been established. Pope looked at hospital admissions from 1985 to 1989 and found that admissions for bronchitis and asthma for all ages were approximately twice as high in Utah Valley as in Salt Lake and Cache valleys when the Geneva Steel Mill was operating.

The Geneva Steel mill in Pope’s study really was a poster boy for polluting industry. I had a job there after Vietnam. I started in the coke plant, a place as close to hell as I hope I’ll ever  get. The process is simple: You bake coal in an oven with very bad seals, until you’ve driven off all the gases and are left with pure carbon, which is used to make steel.

Most of the escaping gases were captured and piped to the U.S. Oxygen & Gases plant to the north, where they were distilled into oxygen, nitrogen, hydrogen and other lesser fractions. The fugitive emissions escaped into the fickle weather patterns and eventually the lungs of Utah Valley citizens. The coke plant was just the dirtiest of a dozen very dirty processes that are involved in making steel.

The particulates in you

Arden Pope had no idea exactly what Geneva’s fugitive emissions consisted of. He just knew that it was having obvious and debilitating effects. As a result of Pope’s study and many others that followed, the bad health effects of PM10s were discovered. As a result of those studies, the EPA set higher air quality standards for PM10s and later imposed standards for PM2.5s.

Twenty-five years after Pope’s study, scientists are focused on ultrafine particulate matter—particles so small that they are absorbed directly into our bloodstreams via our sinuses and lungs.

Our sinuses do a pretty good job of filtering out the so-called “coarse particulate matter” between 10 and 2.5 microns in diameter (a good reason to breathe through your nose). However, that leaves ultrafine particulates, particulates so small that they can only be studied with an electron microscope. These range from 0.1 microns (about a tenth of the size of a bacterium) through 0.01 microns (the size of viruses) down to 0.001 microns (gaseous molecules). The period at the end of this sentence is about 500 microns in diameter.

The very nature of ultrafine particulate matter makes them potent threats to our health. Their tiny size allows them to get past our natural filter systems—the mucous membranes in our nose, mouth and throat. These respirable particulates penetrate into the deepest recesses of our lungs and then into our blood streams. Ultrafine particulates that enter our bloodstream in our noses bypass the blood-brain barrier and can attack the brain directly. A good reason not to breathe through your nose.

Ultrafines’ tiny size give them a much larger active surface area for a given amount of pollution. Because of the very large transfer area of the lungs a large inflammatory response will be called for. Ultrafines’ ability to be absorbed in the blood stream and undergo “interstitialization” (getting stuck in a nook) gives them an immediate health effect and makes them difficult to eliminate from the body. They are so light that they hang around for a long time and can be transported far from their sources. They are also difficult to measure, and their immense variety makes the worst culprits difficult to identify and study.

Double double toil and trouble…Fire burn and cauldron bubble

The three witches in Shakespeare’s McBeth, with their eye of newt and toe of frog, have nothing on modern pollution as mixologists.

Instead, modern pollution mixology employs the atmospheric nitrogen, sulfur in fuel (particularly diesel fuel), oxygen (as needed) and, of course, fossil fuel, in generous quantities. And that’s just automotive pollution. Industrial pollution and the effluent from our furnaces and water heaters have similar chemistries. (Our indoor air is another story that we will tell next month.)

All this mixing takes place in your vehicle’s engine and its exhaust system. Ignition temperatures in internal combustion engines reach 1800 degrees F. The pollution that goes out your tailpipe ranges from products of incomplete combustion—nasty carbon molecules formed in less-than-optimum burning conditions—to exotic metallic molecules formed in catalytic converters when the hot exhaust gases pass through your car’s exhaust system.


The primary effect of ultrafine particles is to supercharge our inflammatory defenses. In an article published in the Journal of Thoracic Diseases, in January 2016, Yu fei Xing et al, found that the “PM2.5 surface was rich in iron, copper, zinc, manganese, and other transition elements (heavy metals), as well as polycyclic aromatic hydrocarbons (smoke from burning coal —the Geneva coke plant) and lipopolysaccharides (important precursors to inflammation). These components can increase free radical production in the lung, consume antioxidant ingredients and cause oxidative stress….Free radicals, metal and the organic components of PM2.5 can induce free radical production to oxidize lung cells, which may be the primary cause of body injury.”

But wait, there’s more!

Researchers have found that ultrafine particles not only damage DNA and suppress DNA repair but can also promote the replication of damaged DNA fragments and consequently prompt carcinogenesis.

Epidemiological studies from around the world have uncovered a surprising number of diseases that can be caused or aggravated by ultrafine particulate matter. The established links between ultrafine particulates and asthma, heart disease, lung cancer and stroke have been strengthened.

New connections have been found between ultrafine particulates and Alzheimer’s, infertility, miscarriages and birth defects, cognitive deficits, Type-2 diabetes, epilepsy, urinary tract infections, pneumonia, Parkinson’s, septicemia, fluid and electrolyte disorders, renal failure, osteoporosis and depression.

It’s possible that a large fraction of modern disease can be traced to air pollution, with air pollution as a gateway disease/ poison that ushers in a host of other diseases.

Diseases caused or aggravated by air pollution

Heart disease

A 2010 study published in Environmental Health showed that “exposure to PM2.5s of less than six hours could lead to arrhythmia, ischemia and myocardial infarction. The active mechanism may involve the autonomic nervous system, systemic inflammation, vasomotor dysfunction and/or thrombogenesis.” The authors suggested that people with cardiovascular diseases avoid such situations, noting, “Guidance for vulnerable persons faced with high sub-daily exposure situations is lacking even if such exposures occur in many real-life situations such as in traffic jams, at bus stops, during accidental fires and explosions, in arenas, in indoor parking garages, during fireworks displays, etc.”

Arden Pope, et al, in an article published in Circulation Research, in 2014, noted, “Growing evidence suggests that long-term exposure to fine particulate matter (PM2.5) air pollution contributes to risk of cardiovascular disease morbidity [sickness] and mortality [death]. There is uncertainty about who are most susceptible. Individuals with underlying cardiometabolic disorders, including hypertension, diabetes mellitus, and obesity, may be at greater risk. PM2.5 pollution may also contribute to cardiometabolic disorders, augmenting cardiovascular disease risk.”

Asthma/pneumonia/lung cancer/respiratory diseases

China is taking a leading role in pollution research as it grapples with the enormous health costs of pollution. A 2016 study by Chinese scientists, published in the Journal of Thoracic Medicine, found that PM2.5s can penetrate deeply into the lung, irritate and corrode the alveolar wall, and consequently impair lung function.

Type-2 diabetes

A massive study involving 1.7 million American veterans over eight years found that the risk of diabetes starts at about 2.4 μg/m3—less than a quarter of current EPA standards. Among people exposed to five to 10 μg/m3 of particulate matter, about 21% developed diabetes—or about twice the national average of 9.4%. For an increase of 10 micrograms per cubic meter of long-term PM2.5 concentration, the risk of diabetes incidence increased by 15.7%.

Alzheimer’s/cognitive deficits

Research has shown that degenerative brain diseases such as Alzheimer’s, mental illness and reduced intelligence can be caused by air pollution. New research from Lancaster University published in the Proceedings of the National Academy of Sciences in 2016 linked toxic nanoparticles from air pollution to Alzheimer’s. Lead researcher Barbara Maher noted that “oxidative cell damage is one of the hallmark features of Alzheimer’s disease, and this is why the presence of magnetite is so potentially significant, because it is so bioreactive.” Maher noted, “We also observed other metal-bearing particles in the brain, such as platinum, cobalt and nickel. Things like platinum are very unlikely to come from a source within the brain. It is a bit of an indicator of a [vehicle] catalytic converter source.”

Infertility/miscarriages/ birth defects

The American Journal of Epidemiology in 2013 published research from Stanford University that found an association between specific traffic-related air pollutants and neural tube defects, which are malformations of the brain and spine. “When researchers looked at a subset of women who lived within five kilometers of a monitoring station, they found that for every 10 ug/m3 increase in PM 2.5 levels women experienced during the month after conception, their babies were 19% more likely to be born with birth defects.”

Dr. Emily DeFranco of the University of Cincinnati College of Medicine in Ohio writes, “There are several particularly vulnerable exposure periods near the time of conception, both before and after conception, in which exposure to higher levels of particulate matter in the air may pose an increased chance for a birth defect to occur.”

Osteoporosis/poor bone health

A study published in Bone Health found that “inhalation of polluting particles could lead to bone mass loss through the oxidative stress and inflammation caused by air pollution.” Interestingly, no correlation was found with use of biomass fuel for cooking. We will look at indoor pollution next month and explore particulate matter released by indoor cooking.


People exposed to an increase of 10 micrograms per cubic meter (µg/m3) in the level of PM2.5 for a year or more had a 10% higher risk of getting depression. “We know that the finest particulates from dirty air can reach the brain via both the bloodstream and the nose, and that air pollution has been implicated in increased [brain] inflammation, damage to nerve cells and to changes in stress hormone production, which have been linked to poor mental health, a 10µg/m3 increase over three days raising the risk of suicide by 2%”. —Braithwaite et al, Environmental Health Perspectives, 2019


Air pollution finally got economists’ attention when it was found that there actually are economic costs of pollution. In 2019 the London School of Economics published an article that concluded that “a narrow focus on traditional health outcomes, such as morbidity and mortality, may understate the true benefit of reducing pollution, as air pollution also affects scholastic achievement and human capital formation.” (You have to wonder whether Trump’s Secretary of the Treasury, Steven Mnuchin, was under the influence of air pollution when he studied economics.)

Don’t hold your breath

There are other things you can do!

Research from around the world is showing that air pollution, particulate matter in particular, is a much more insideous threat to our health than originally believed. National Air Quality Standards, as administered by the EPA, have failed to keep up with these new findings. Research is showing real health hazards at less than a quarter of EPA limits. In fact many of the studies are showing that chronic doses, even at low levels, can cause a large number of many common diseases. Acute doses, even at what the EPA considers moderate levels, can kill those with advanced stages of these diseases within hours or days.

So, it comes down to you. There is no point in waiting for good air quality regulations from the federal government. We can’t hold our breath that long. The first step in protecting yourself and your loved ones is knowing what the current air quality is.

I have the Utah Division of Air Quality site bookmarked on my computer and it’s fascinating to compare the air in neighboring counties. The poor air quality resulting from fugitive methane emissions from the oil and gas fields in the Uintah Basin readily becomes apparent on days when the rest of the state has clean air.

On a county-wide averaged basis, the UDAQ numbers can look pretty good unless you take into account recent scientific evidence of the dose specificity of the worst air pollutants. Dose specificity means that the effect is proportional to the dose. Twice the dose equals twice the effect. It also goes the other way—half the dose equals half the effect. But only zero dose equals zero effect.

That is all good, as far as it goes, but there are only four UDAQ particulate matter monitoring stations in the Salt Lake Valley, two in Weber County and one each in Cache, Box Elder, Davis, Utah and Uintah counties. A lot of pollution can happen between the Bountiful sampling site and the site at Hawthorne Elementary at 1700 South and 700 East.

Another problem is that the air quality is not uniform across the valley. Storms can slosh the pollution back and forth along the Wasatch Front. With a wind coming from across the lake, the air in the Avenues can be fresh as the proverbial breeze and Magna might as well be sucking on a tailpipe. Or, vice versa, if the wind is coming from a slightly different direction.

Knowledge is power (so are high-tech machines & diet)

One answer to the problem of chunky air quality data is PurpleAir, a public network of particulate matter sensors that uses a new generation of laser particle counters to provide real time measurement of PM1.0, PM2.5 and PM10. There are about 600 sensors in Utah, most situated from Ogden to Provo. We’ll say much more on this next month but in the meantime check out the map on their website,; you can zoom in to your very own neighborhood! For PurpleAir’s origin story, check out

The idea of a defensible space is useful when considering what you can do about bad air. The second step is to clean the air you plan on breathing. Filtering the air in your entire house, 24/365, will be expensive both upfront and with frequent, necessary filter changes. You may want to filter the air in the rooms you spend the most time in.

Cleaning up ultrafine particulate matter is challenging. Only the best filters can do an adequate job. High Efficiency Particulate Air (HEPA) filters, which are common in air filtration systems, do a good job of filtering out the coarse particualtes but miss the ultrafines that are really the problem. No filters intercept 100% of ultrafine particles. The best current defense is running an air cleaning system with an Ultra-Low Particulate Air (ULPA) filter medium, which is designed to remove 99.999% of particulates 0.12 microns or larger. The problem is that ultrafine particulates start at 0.1 microns and get smaller, so you are going to have to cycle your air through the system multiple times to make a dent in the ultrafine particulates.

The third step is making sure your diet is full of oxidation- and inflammation-fighting foods and supplements such as animal-based omega-3 fats, antioxidant-rich vegetables and vitamins C, E, B6, B9 and B12. We’ll have more about food and supplements to fight the effects of air pollution in next month’s issue.

Caught in a TRAP*

Many studies have found a direct correlation between proximity to highways and the ill effects of air pollution. What are euphemistically called “lower socioeconomic status neighborhoods” suffer the worst effects of traffic-related air pollution* (TRAP). Persons in lower socioeconomic status neighborhoods don’t have the resources to deal with the health burden of elevated pollution levels.

One solution is to move away from sources of pollution. That’s not always an option. No one has done a study of how quickly, or slowly, pollution density falls off as you get further from a major highway. You could probably get a pretty good idea by charting real estate prices around major sources of pollution.

Findings on heavy traffic and ultrafines might make you want to filter the air in your car. There are limited options for doing that. Most products are good only at filtering out the big stuff that really isn’t the problem. Newer cars are beginning to have built-in air quality conditioners, but frequent filter changes are still necessary.

Another avenue of relief could come from  efforts to reduce traffic jams. A program aimed at unjamming traffic by voluntarily staggering work hours could significantly reduce exposures to traffic-related air pollution of commuters and those living in lower socio­economic status neighborhoods.

London, England has a program to build green barriers along major highways as a means of mitigating air pollution, in particular ultrafines. “London’s green infrastructure includes a network of parks, green spaces, gardens, woodlands, rivers and wetlands. It also includes street trees, hedges, green walls and green roofs.” (Greater London Authority, April 2019)

Utah enjoys clean air most of the time, particularly when storms keep the valleys along the Wasatch Front cleaned out. We need to take advantage of our air when it is clean. Go running but never along a trafficed roadway. Take your dog to the park.

Dealing with pollution ultimately leads to one big realization: It’s a lot easier to eliminate the cause than to clean up the mess. Conserving energy every which way, on every level,  will always be the most direct way of reducing air pollution.

To Conclude (for now….)

New findings show that everyone is to some extent vulnerable to the effects of chronic pollution. It now looks likely that many victims of a variety of diseases actually contracted their diseases from bad air, where it was previously presumed bad air aggravated a condition they had contracted some other way.

The air regulation establishment must have a disheartening sense of the ever-receding bonanaza. Just when the numbers are starting to look good the bar needs to be raised.

Thirty or forty years ago, when Kennecott was the 800-pound bad-air gorilla in the valley, I read a letter to the editor in the Los Angeles Times from a Kennecott executive, saying that he had no heartburn, or asthma for that matter, over the pollution emitted by Kennecott’s pit and smelter operations. He noted that he could see the smelter from his house, even on bad air days. My guess was that the executive lived in the upper Avenues rather than Magna or Taylorsville, and could indeed, see the top of the smelter smoke stack, towering over the pollution-filled valley.

The discovery of ultrafine particulate pollution’s ill effects is news, but there are other unresoved air quality issues. Many serious pollutants were left off the EPA’s list of criteria pollutants for reasons of economy. The economic health of many corporations would suffer if they were made responsible for their poisonous externalities and Congress hasn’t funded the research needed to set criteria for regulations. That’s only correlation, not causality.

The chlorine that the Magcorp magnesium smelter on the west side of the lake puts out by the millions of pounds per year is one example. Magcorp would out of business if they had to stop emitting chlorine. An argument could be made that the EPA should set criteria for many more pollutants, but corporate citizens will never let that happen.

The dirty air lobby and their paid sock puppets in Congress (“It’s not bribery, it’s campaign contributions! It’s not money, it’s free speech!”) deny any causal connection between bad health and air pollution, saying regulations should not be set to protect human health until the exact mechanisms are understood. In today’s political environment it doesn’t look like we can expect any help from the federal govenrment. Hopefully these new findings on ultrafine particulate matter will prompt needed changes.

This article was originally published on January 29, 2020.