The Secrets of Smog: What You’re Not Being Told

The most polluted area of the United States is in the San Joaquin Valley. The valley offers a glimpse into the toxins and hazards inside the smog that hides the mountains most days.

One element that significantly contributes to pollution in the valley is its unique geography. It is at once an area of abundance and at the same time cursed by its resources and microclimate.

Along with its Mediterranean-like climate, the valley benefits from the abundant Sierra Nevada snowmelt used for irrigation crops.

This supports an agricultural bonanza - including citrus fruits, nuts, and field crops, like alfalfa. Sunflowers almonds, table grapes, wine grapes, oranges, lemons, peaches, cherries, and plums are also grown in its unique micro-climate.

Beyond that, the region is rich in oil reserves, particularly in areas like the Kern County oil fields. The discovery of oil there, in the early 20th century, eventually led to the establishment and expansion of numerous refineries.

Because of its almost Galapagos-like seclusion, far past the hills of Los Angeles, it is also a major transportation hub—for all those crops and refined oil and the inbound goods needed to support its isolation and industries.

The dark side of abundance

Oil extraction, mining, and refining activities release pollutants such as volatile organic compounds (VOCs), particulate matter (PM), and toxic air contaminants linked to respiratory disorders, cardiovascular diseases, and cancers.

The valley's extensive agricultural operations generate dust, pesticides, and diesel emissions from machinery. These pollutants also contribute to poor air quality, exacerbating respiratory conditions like asthma and chronic obstructive pulmonary disease (COPD).

The non-stop transportation in and out of the valley, with diesel vehicles slogging up steep, sloping hills to carry goods in and out of the region, produces fine (PM2.5) and ultrafine (diameters less than 0.1 micrometers) particulate matter.

Ultrafine Particles

While PM2.5 particles are most commonly measured as an indicator of pollution, ultrafine particulate matter is not. Ultrafine particles are very difficult to measure because of their mass and size. Because PM2.5 particles are typically measured in terms of "mass," the number includes all particles between the range of 2.5 microns and 0.01 microns.

It is estimated that in highly polluted areas - like the San Joaquin Valley - that between 20-30% of all PM2.5 particles are ultrafine particles sized less than 0.10 microns.

Ultrafine particles (UFP) can be especially dangerous. That's because they're often bound with heavy metals and dangerous molecules, and they can penetrate deep into the lungs and diffuse across cell membranes without molecular transport assistance, which is the normal process that protects cells from foreign particle invasion.

The heavy metals present in the combustion of fuels or raw materials (e.g., lead, cadmium, arsenic, mercury) can volatilize and condense into non-carbonized ultrafine particles.

Dangerous molecules such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals can adsorb onto UFP surfaces (attach) enhancing their toxicity. While still ultrafine in size, they carry a payload of carcinogens in that adsorbed state.

With those carcinogens attached, they can enter the bloodstream, diffuse into cells, and at times, diffuse across the blood-brain barrier. Another pathway into the brain is through the olfactory nerve. UFPs interact with endothelial cells, leading to transcytosis or passive diffusion. This can lead to neurodegenerative disorders and Alzheimer's disease.

Source: Oberd?rster, G., Elder, A., & Rinderknecht, A. (2009). Nanoparticles and the brain: Cause for concern? Journal of Nanoparticle Research, 11(3), 271-284. DOI:10.1007/s11051-008-9506-9

Pesticides can aerosolize and mix with smog

Some of these carcinogens are from chemical pesticides used on the valley's crops: https://www.enn.com/articles/75228-residents-in-san-joaquin-valley-breathe-chemical-pesticides-according-to-new-study

A separate UC Davis study revealed "detectable levels of pesticides in a significant proportion of participants’ samplers. Specifically, 22% of adults and one school-aged child had measurable levels of at least one pesticide in their samplers, including compounds such as 1,3-dichloropropene, chlorpyrifos (despite its banned status in California), pyrimethanil, buprofezin, and penthiopyra."

https://health.ucdavis.edu/news/headlines/residents-in-san-joaquin-valley-breathe-chemical-pesticides-according-to-new-study/2024/09?

Particles and their carcinogenic hitchhikers

We should see that pollution is so much more than just "smog." It's a vaporous cauldron of gases, particles, heavy metals, and carcinogenic molecules.

Within this witches' brew are toxic molecules are non-carbonized fine particles or ultrafine particles attached to PAHs, dioxins, furans, and VOCs like benzene and formaldehyde. Heavy metals such as lead, arsenic, cadmium, mercury, chromium, and vanadium also attach to fine or ultrafine particles or exist as separate molecular structures within the smog.

The Secrets of Smog

For many in the Valley, the view of the surrounding mountains is obscured by a heavy smog, sometimes grey, sometimes tinged with yellow.

Within the smog, there is indeed a brew of population health dangers. It's commonly known that pollution poses respiratory and cardiovascular hazards - but there's more.

Within the smoke-like vapor, there are specific metal and molecular ingredients most commonly linked to Leukemias and Lymphomas.

The chemicals include arsenic and cadmium, which have the strongest links to leukemia, with arsenic often linked to occupational or environmental exposure. Lead and mercury are also contributors, especially in long-term or high-dose exposures.

Benzene, which can be found as a by-product of the local refineries, damages bone marrow, leading to chromosomal mutations and, often, leukemia diseases.

Formaldehyde, which is also also found in smog, can cause DNA damage and disrupt cellular repair mechanisms.

What's the answer?

The California Air Resources Board https://ww2.arb.ca.gov is very active in addressing pollution issues statewide. The solution is to prevent the source.

In the meantime, it's important to understand INDOOR AIR QUALITY and how to remediate small particles and toxins (volatile chemicals) that may exist indoors.

I would recommend, at a minimum, installing an indoor air quality monitor that measures PM2.5, VOC (formaldehyde), and TVOCs (the existence of toxic volatile compounds, including benzene, toluene, PAH, limonene, etc).

There are rather effective solutions to trap UFPs and PM2.5 particles, such as HEP air filters, and many include activated charcoal that can help absorb some volatile compounds and molecular hazards.

When selecting an air filtration system, choose wisely. Help on selecting a proper air filter can be found on the EPA and CARB websites.

I would recommend highly rated indoor air quality monitors that can measure particle counts, not mass, and display PM1.0, PM2.5, VOC, TVOC, and Temperature, and, ideally offer a comparison between indoor and outdoor Air Quality.