Last year, as the Tubbs Fire scorched its way across Napa and Sonoma counties, environmental researchers at the University of California, Davis, fielded questions about the health impact of chronic exposure to smoke from a wildfire that torched trees and urban structures alike.
“Everyone had concerns about their health and what was in the smoke,” said Schmidt, who studies how environmental exposures influence child development. “We just didn’t have any answers to those questions, and when we looked and searched to see what was out there, we really found there wasn’t much.”
Yet studies on air pollution do offer up clues to what happens when the human body is under assault from microscopic particles in the air, Pinkerton said. The UCD professor has spent decades studying the effects of air pollution on lung inflammation and disease.
Longer-term, Pinkerton said, the health of people breathing in smoke from the wildfires might well depend on the degree of their exposure and whether the microscopic particles floating in the air manage to worm their way deep into lungs and circulatory systems.
When exposed intermittently to bad air days, Pinkerton said, the average healthy person may experience irritated eyes, scratchy throats, a cough, maybe tightness of the chest, even wheezing. Other experts said people also report shortness of breath, headaches and nosebleeds.
Various hospitals around Northern California are reporting a slight uptick in emergency room visits by people experiencing respiratory issues: In Sacramento, that includes both Kaiser Permanente and Sutter Medical Center.
Other hospitals are seeing a surge of patients: In Sonoma County, emergency room doctors at St. Joseph health hospitals reported an influx of patients equal to what they saw when the Tubbs fire raged across their county last year.
Doctors urged residents to monitor air quality, either through government sites such as www.airnow.gov or www.sparetheair.com, or via local news media. Stay indoors as much as possible, said Dr. Nicole Braxley, medical director of the emergency department at Carmichael’s Mercy San Juan, and use N95 respirator masks when outdoors.
“Even if you’re a completely healthy person, there’s no reason to expose yourself to these particles,” Braxley said. “You might cause yourself harm.”
With progressive exposure to the wildfire smoke, Pinkerton said, healthy people tend to adapt to the conditions: Their eyes are not quite so irritated. They don’t necessarily have that scratchy throat anymore. They cough less and their throats aren’t as tight.
“When we have repeated exposures, our bodies hunker down,” Pinkerton said. “It says, ‘OK, I know this is a bad situation, so I’m going to make some changes.’ The changes are all subconscious. We may breathe a little less deeply. Our cells might be a little bit more responsive in terms of not putting up lots of inflammatory factors. The epithelial cells that line our airways would become tolerant, meaning they’re not so easily damaged.”
Does that mean there is no risk of longer-term damage to the body?
Actually, Pinkerton said, chronic exposures to fine particulates could elicit other responses.
For instance, there’s evidence that it can lead to asthma. In 1996, as the Olympics got underway in Atlanta, city officials acted to minimize the amount of traffic allowed within city limits, Pinkerton said, and there was a statistically significant drop in the percentage of people coming to emergency rooms with asthmatic symptoms.
Links also have been found between exposure to traffic pollutants and problems with pregnancies, Pinkerton said. Studies have shown that pregnant women who live downwind of freeways were more likely to have premature births and to deliver low birth-weight infants. Both conditions are associated with higher risk of infant mortality.
And, Pinkerton said, research also has shown that animals that breathe in particulate matter while pregnant have a tendency to deliver offspring with asthmatic lungs.
One of the greatest concerns that researchers have, Pinkerton said, is whether an embryo will have a tougher time implanting to the uterine wall if its mother is exposed to the fine particulate matter of wildfire smoke during the first trimester.
While doing research in Napa and Sonoma counties, Schmidt met several women who asked whether breathing in wildfire smoke could have caused them to lose their babies. She had to tell them there was no answer yet to that question. They asked to be included in the study, Schmidt said, because they wanted the answer.
For that study, Schmidt and her team collected bio-specimens from the women — hair, blood, saliva, even placenta and umbilical cord blood. They will use the hair to check for bio-markers of stress, and they’ll also look at the specimens to determine which pollutants were present and measure their impact.
UCD researchers have funding to follow the babies’ progress for a year and are seeking funds to continue monitoring them through preschool. Their mothers have provided information on their exposure to the fire and to smoke and on protective measures they took, so researchers will be able to compare children who had greater exposure to those who had less. They’ll also be able to compare all the children to data on children in the general population.
Respiratory and reproductive systems are not the only vulnerable targets in the body.
Pinkerton explained: “When we talk about particulate matter, or PM, we always think, ‘Oh, well, the target organ is the respiratory tract, the lungs, but far more people have problems with cardiovascular disease morbidity and mortality due to PM exposure than respiratory conditions.”
The fine particles being deposited in the lungs don’t necessarily stay there, Pinkerton said, and even if they do, that doesn’t mean their presence isn’t felt by other parts of the body. Researchers have posited several theories about how these particles affect other organs and systems.
The most common belief is that, during the lung’s exchange of oxygen into cells, the microscopic particles hitch a ride into the circulatory system and subsequently cause problems in human organs or in blood vessels.
The greatest concern, Pinkerton said, is that these particles are attaching themselves to plaque formations in blood vessels. Those formations are already bad news, because they’re composed of fat, cholesterol, calcium, and other substances. It’s believed, Pinkerton said, that the particles could provoke inflammation that ultimately triggers a heart attack or stroke.
Another theory, Pinkerton said, is that particles in the airway can disrupt how critical nerves perform their job. There are nerves in the bronchial tree that give automatic feedback to the heart and brain: Narrow the airway. Expand the airway. Speed up the heartbeat. Slow down the heartbeat.
In essence, these nerves are part of the control system for the human flight-or-fight mechanism, Pinkerton said, but when the tiny particles land in the bronchial tree, they somehow delay or dampen the signal. That means the heart no longer immediately responds, said Pinkerton, noting that these are relationships UCD researchers found as part of their research on the health effects of secondary cigarette smoke.
Because of the dearth of research on fine particulate from wildfires, an interdisciplinary team of UC Davis researchers sought funding from the National Institutes of Health to study the impact of breathing in fine particulate from wildfires in urban areas.
The data from those studies is just coming in for analysis: survey responses from hundreds of people living in or near the wildfire boundaries, analysis of ash and gases from urban neighborhoods like Santa Rosa’s Coffey Park that were consumed by the blazes, sophisticated computer models of the movement of the smoke plume.
This kind of scientific research is challenging, Schmidt said, and the toughest part is going to people who have been traumatized by the disaster and asking them to participate in a study. When they approached residents in fire-stricken communities, she said, roughly 2,000 households and 200 women pregnant at the time of the Tubbs Fire volunteered to participate.
“Usually, when we think about poor air quality, what we’re dealing with is a day or two, not a prolonged, several-day period,” Pinkerton said. “If we continue to have bad air for more than a week, that certainly is a concern. ... We oftentimes have asked the questions: What is the effect of chronic exposure? Is there a cumulative effect every day that we breathe particles? Is it building up? Is it doing something in that way?”
Researchers at UC Davis are moving closer to some answers.