Call it a pollution double whammy.
People in the central San Joaquin Valley have been breathing smoke from the Ferguson Fire for nearly a month, but there’s more than a brown shroud of smoke that is making the air putrid and dangerous to breathe. Ozone, a corrosive gas that sears lungs, is building up to unhealthy and very unhealthy levels.
Ozone — you know it better as smog — relies on sunlight and heat to cook vehicle exhaust and other noxious fumes into a toxic brew. Smog typically takes center stage in the Valley’s pollution theater in the summer, but this year the wildfire has been choking the area with tiny dots of soot. The itsy-bitsy particles called PM2.5 have been dangerously dense, catapulting the Valley to pollution levels higher than seen in Beijing.
Now ozone is elbowing its way through the haze. Wildfires can create ozone-making gases called oxides of nitrogen on their own, but the Valley seldom needs the help. Smog spikes on hot afternoons, and for example, on Thursday at 2:20 p.m. ozone in southeast Fresno had climbed to a concentration of 119 parts per billion, which is a very unhealthy level. In other areas of Fresno County, the levels were high enough to be unhealthy for sensitive groups (pregnant women, children, people with asthma and heart and lung conditions).
“I am really concerned for the vulnerable populations in Fresno that might be exposed to the fire pollution along with the other routine pollutants like ozone — or even dust from farming,” said Rhonda Spencer, an associate professor at Loma Linda University School of Public Health.
Nasty all by themselves
Each pollutant by itself is nasty. Ozone is a strong irritant in the lungs and has been associated with a host of health problems, including increased mortality, reduced lung growth in children and aggravation of asthma and other respiratory symptoms. Microscopic particles have been associated with inflammation in the lungs and have been linked to premature death, increased risk for heart attack and stroke. Particulate pollution also has been shown to trigger asthma attacks and aggravate other respiratory conditions.
It can be difficult to know what is in wildfire smoke to accurately gauge how dangerous it is to breathe. Besides soot from burned trees there could be debris from burned structures. Research on particle pollution typically has focused on particles generated from diesel and vehicle exhaust, among other urban sources.
There are studies that have looked specifically at exposure to PM2.5 from wildfires and the research points to respiratory effects and even deaths. Studies in California after fires in 2008 found “effects that were significant for hospital admission,” said Michael Jerrett, a professor of environmental health sciences at UCLA. The admissions were for respiratory problems and not for cardiovascular, he said.
The studies of the fires also found that people living in ZIP codes with lower socioeconomic status tended to have a worse response to the wildfires. Jerrett cited factors that might contribute to this result: lower-income residents may have had other health conditions that they had not received proper medical care for; and they may have had limited options to evacuate (or otherwise get away) and were exposed to higher doses of pollution from the fires.
Research is scant about what happens to lungs and hearts when you lump exposure to ozone and wildfire smoke together to make a pollution soup.
“It’s something we should be investigating as these fires become more prevalent,” Jerrett said.
Determining if there is a dual effect won’t be easy, said Alvaro Alvarado, supervisor of the health and ecosystems assessment section at the California Air Resources Board. “It’s difficult to tease out the effects of one over the other,” he said. It makes sense, though, that inhaling a combination of ozone and particles is not a good scenario, he said. “It’s just a difficult question to study with people.”
Studying the smog/smoke combo
Children are known to be susceptible to ozone and to particles, and one Air Resources Board study looked at exposure to combined ozone and wildfire particles that could have implications for children. The researchers found effects to the lung function and immune system of rhesus monkeys born three months prior to the 2008 wildfires in Trinity and Humboldt counties. The monkeys were exposed to both ozone and wildfire PM2.5.
The Air Resources Board has sponsored other studies that have looked at the pollutant combination. One study of adult rats with and without pre-existing heart disease found that both sets of rats were more affected by exposure to both pollutants. But rats with pre-existing heart disease were susceptible to either ozone or the combination of ozone and ultrafine particulate matter.
On the other hand, another Air Resources Board-sponsored study of heart-related hospitalizations and deaths found effects from exposure to both ozone and PM2.5 were not worse than exposure to the individual pollutants.
A Loma Linda University smog study of 3,239 nonsmoking, non-Hispanic white adults found a combination of exposure to particulate pollution and ozone might be worse for women’s heart health. The researchers found chronic exposure to particle pollution increased the risk of fatal coronary heart disease, and showed the risk was stronger in women, especially when they also had been exposed to other air pollutants, especially ozone.
More research has to be done to make an airtight health case against an ozone/particulate combo, but don’t expect to hear anything about health effects of breathing an ozone/smoke cocktail from the Ferguson Fire. Investigations take time to set up. Any health investigation of the Ferguson Fire couldn’t take place for at least a year or two, said Patrick Wong, a toxicologist with the Air Resources Board.
Health effects for each are bad
For now, scientists emphasize evidence has piled up on the detrimental effects of individual exposure to high levels of ozone and individual exposure to high levels of PM2.5. Exposure to either should be avoided, they said. And pregnant women, children and the elderly are especially susceptible to ozone and PM2.5.
Exposure to ozone has been shown to reduce lung function in children by up to 20 percent, for example, said Jerrett. “Once the lung function is depleted, the person is being set up for further complications through life,” he said.
PM2.5 particles — miniscule spears of soot, dust and grime — carry their own threats. They are so tiny they can zip past the lungs’ defenses and mess with the heart. Some studies have shown an association with long-term exposure and the creation of plaques in coronary arteries that can break off and cause stroke and heart attacks. PM2.5 is the shorthand for fine particles with diameters that are 2.5 microns or less in size. A micron or one-millionth of a meter is about one-seventh the diameter of a human hair.
Exposure to particles in the first and second trimesters of pregnancy have been associated with an increased risk of premature births and babies born with low birth weights.
Children are prone to serious breathing problems from acute exposure to fine particles, especially if they have asthma. (And who doesn’t know a child with asthma in the Valley?)
Parents in the Valley have been keeping watch over children since the first sight of the plumes of smoke from the Ferguson Fire that erupted on July 13.
Ivanka Saunders of Fresno is worried about a potential smoky start of school on Monday. Her son, Dyami Hunt, 14, has asthma. For the past week, Dyami has been recovering from walking pneumonia, which Saunders suspects is connected to the smoky air despite the fact that she has made him wear a mask whenever he has stepped outside.
“This isn’t our normal bad (air) season,” Saunders said.
Dyami has been told he must wear a mask when he is outdoors during the school day, but Saunders worries he will forget or be embarrassed to keep a mask on. “It should be the odd man out is the one who doesn’t have the mask on.”
Leticia Renteria of Clovis cannot remember a summer where she has been so worried about her daughter, Makayla Renteria, 18, having a severe asthma attack. “I try to minimize her time outside,” she said. “I wouldn’t even let her throw out the garbage.”
Makayla, a senior at Clovis High, has had to take her asthma inhaler with her to golf practices, which lately have been canceled because of smoke. After each practice, she’s had to have a breathing treatment at home to prevent an asthma attack, her mom said. “I’ve never had to go this far, with this much medicine.”
The San Joaquin Valley Air Pollution Control District has been monitoring smoke belching from the Ferguson Fire and several others burning in California. Spokeswoman Jaime Holt said smoke is expected to drift down into the Valley floor through the weekend. “There will be poor air dispersion, high temperatures and smoke impacts,” she said.
Ozone levels also are monitored and are expected to increase even more as the school year begins in Fresno next week. Traffic increases with parents dropping kids off at school and picking them up, adding to the Valley’s already exhaust-laden air.
There is a sliver of good air news. Firefighters have stomped out a lot of the Ferguson Fire that has cloaked Yosemite Valley in smoke for weeks. Firefighters reported they had 80 percent containment of the fire on Friday. The air district is hopeful that smoke levels will drop soon, Holt said.
The Valley is not out of the woods, though. The air district is concerned about smoke from the Holy Fire in Orange County being pushed into the Valley.
As long as there’s a wildfire spewing smoke somewhere that drifts into the Valley, Spencer of Loma Linda University recommends caution when being outdoors, especially for pregnant women and children. “Even if you can’t see it or think it’s not bad, there can be drastic consequences that come from vulnerable populations being exposed.”