Viviana Aguirre, 14, knows the air is bad when she has to reach for her inhaler once, maybe twice a week.
But this summer, the high school freshman has relied on her inhaler almost every day to keep her asthma under control.
The air in her low-income neighborhood has been thick with smoke for weeks, she said, forcing her to remain indoors most of the time. It's hard for Viviana to tell whether the smoke is coming from the usual controlled burns in the farmers' fields surrounding her home — or from the record-breaking wildfires blazing to the north and south of her, she said.
"I do see smoke," Viviana said, "but I see smoke most of the time."
People like Viviana and her family are hit disproportionately when wildfires ignite — because smoke adds another layer of toxic substances to the already dirty air, experts say.
"Without a doubt, these communities are at higher risk" when fires break out, said Emanuel Alcala, a postgraduate fellow with the Central Valley Health Policy Institute at California State University-Fresno. "Especially because you already have other environmental hazards: toxic waste sites, poor quality of water, and sometimes no air conditioning."
More than a dozen major blazes still rage across California, including the two Mendocino Complex fires in the northern part of the state that together have charred nearly 460,000 acres. One of those fires, the Ranch Fire, is the largest in state history.
Fires are also burning in Colorado, Oregon, Washington and Idaho. Smoke from these blazes has drifted as far as Ohio. Portions of northern Nevada recorded some of their worst ozone pollution ever last month because of the fires, and officials across the West have issued health warnings to alert sensitive groups — such as young children, older adults and people with respiratory diseases — of the potential risks.
In neighborhoods like Viviana's, which lies within a few miles of dairy farms, packing sheds and oil fields, particulate and ozone pollution already poses a health threat. The air is sullied by a constant, diesel-spewing stream of big rigs as well as pesticides and dust from agricultural operations.
The smell of petroleum and cows saturates the neighborhood, said Gustavo Aguirre, Viviana's dad, and creates a toxic brew with the wildfire smoke.
"When I go outside just to hang out with my friends, I start coughing and I have to come back in," Viviana said.
About 26 percent of school-aged children in the San Joaquin Valley have asthma — the highest rate in the state, according to California Health Interview Survey.
Cities in the San Joaquin Valley, the state's agricultural heartland, top the list of those with the worst air pollution in the country. The valley is also home to some of the state's poorest communities: Seven of the 10 California counties with the highest child poverty rates are there, according to a 2017 report by the San Joaquin Valley Health Fund.
"The geography and climate of the valley can trap unhealthy air for days, if not weeks," said Will Barrett, clean-air advocacy director for the American Lung Association in California.
The combination of industrial ozone and fine particulate matter from wildfire smoke becomes trapped between the mountains surrounding the valley and pushes air quality to dangerous levels. "You're combining two of the most widespread and pervasive pollutants," Barrett said. "It really is a double whammy."
Adding smoke to existing pollution can not only exacerbate someone's asthma symptoms, but also trigger new cases of the respiratory disease, said Dr. Kari Nadeau, director of the Sean N. Parker Center for Allergy & Asthma Research at Stanford University.
In some cases, all it takes is about five days of exposure to wildfire smoke for people without asthma, especially children, to develop wheezing, coughing and other symptoms, she said.
In already polluted places like the San Joaquin Valley, "the wildfires worsen your rates of asthma by fourfold and increase the rate of heart attack by 42 percent," she said. "This is just going to make it exponentially worse."
In southwest Fresno, a community dense with public housing, Maria Garcia, 62, lives within 2 miles of a poultry processing plant, warehouses and Highway 99.
Garcia considers herself healthy, but a persistent cough this summer left her gasping for air.
She compares some of her recent symptoms — such as chest pressure and headaches — to those experienced by her adult son, who has asthma.
"My guess is it's probably the smoke," Garcia said.
Other regions in the state also are suffering. Smoke from the Mendocino Complex fires has drifted into the San Francisco Bay Area, about a three-hour drive south of the blazes.
A mobile asthma clinic called the Breathmobile provides free appointments and pulmonary function tests for children at East Bay schools with a high number of students enrolled in Medi-Cal, California's Medicaid program for low-income residents, said Mary Frazier, a registered nurse and project director of the Northern California Breathmobile program.
"Kids on Medi-Cal have more asthma," she said. "It can be because they are exposed to more triggers. They live in low-income housing, which has some poor indoor-air quality and the houses are near freeways or industry."
When she starts visiting kids again in September after classes resume, Frazier knows she will encounter many children who have been coughing and wheezing because of the smoke.
Back in southwest Fresno, Gary Hunt, 54, has remained mostly housebound this summer, leaving only for important errands and medical appointments. Even then, he wears a mask.
Pollution from fires are "definitely making a drastic difference," worsening Hunt's asthma, causing more fatigue, chest pain and headaches, he said.
But extinguishing wildfires doesn't guarantee relief. There is a meat-rendering plant near his home, and busy state Route 41 is about a quarter-mile away.
"Because of where we are, we don't really get a break," he said.
Three years ago, Hunt had a severe asthma attack that sent him to the hospital. He had to leave his job as a school maintenance worker and lost his job-based insurance. He enrolled in Medi-Cal, and soon learned that not all doctors accept public insurance — which means that getting quick access to care during fire season can be a problem.
For instance, he said, he needs to see a pulmonologist — but has to wait three months for an appointment.
People with Medi-Cal or those without insurance can in some cases wait up to a year for treatment, said Kevin Hamilton, a respiratory therapist and CEO of the Central California Asthma Collaborative.
Hunt said he is frequently asked, even by doctors, why he and his family don't move to a healthier community. The answer is that he simply can't afford it.
"If I could, I wouldn't be here," he said.
KHN's coverage of these topics is supported by California Health Care Foundation and Heising-Simons Foundation
This story was produced by Kaiser Health News, which publishes California Healthline, a service of the California Health Care Foundation.
This article was reprinted from khn.org with permission from the Henry J. Kaiser Family Foundation. Kaiser Health News, an editorially independent news service, is a program of the Kaiser Family Foundation, a nonpartisan health care policy research organization unaffiliated with Kaiser Permanente.