by: PHOTO COURTESY OF FRIENDS OF TREES – Friends of Trees volunteers plant some of the 60,000 trees added along Interstate 205 in a four-year project. The corridor has high rates of air pollution and asthma.
Trees won’t cure the Portland area’s asthma problem, but they can help ease some of the suffering.
Recent studies have linked asthma to vehicle emissions from nearby highways and documented how even tiny pockets of trees can reduce local air pollutants.
Now new maps created by the Coalition for a Livable Future can pinpoint where asthmatics live in the Portland area, down to the block level, enabling researchers to overlay maps showing other factors associated with the disease. As expected based on past research, the maps show high asthma rates in low-income
areas and neighborhoods with many people of color. They also reveal higher rates alongside freeways and highways, which tend to have relatively few trees.
As analysts study the maps in coming months, they hope to gain new understandings of the links associated with asthma, and devise land use, environmental, housing and other policies to reduce asthma
“If you put people next to freeways, there’s going to be public health consequences,” says economist Geoff Donovan, who has studied trees for the U.S. Forest Service in Portland. “We can’t put new parks in” everywhere, Donovan says, “but we can put trees.”
Friends of Trees targets its tree-planting efforts on low-income neighborhoods with subpar tree canopy and high levels of air pollutants, says Scott Fogarty, executive director of the Portland nonprofit. Over the past four years, the group planted 60,000 trees along Interstate 205 in East Portland.
His group is a member of the Coalition for a Livable Future, so Fogarty wasn’t exactly surprised when he delved into the group’s new interactive maps, called the Regional Equity Atlas 2.0.
“Clearly the data shows that neighborhoods that appear to have a high or the highest asthma rates in the city are the ones with low canopy rates,” he says.
A known killer
by: PHOTO COURTESY OF COALITION FOR A LIVABLE FUTURE – For the first time, maps created by the Coalition for a Livable Future can pinpoint small geographic pockets where residents have alarming rates of asthma.
Asthma is a chronic lung disease causing shortness of breath, coughing and wheezing. Oregon has one of the nation’s five highest asthma rates, afflicting more than 300,000 adults and 83,000 children, according to an Oregon Health Authority report, “The Burden of Asthma in Oregon.” In the decade before the report was released, 47 to 78 Oregonians died each year from asthma, and one in seven sufferers wound up in an emergency room due to an asthma attack in 2007.
The causes of asthma aren’t exactly known, though scientists believe some have a genetic predisposition to it. Many things can trigger asthma attacks: cigarette smoke, air pollution, mold, pollen, cockroaches, dust mites, pets and chemical irritants.
In past years, health analysts relied on data from hospitalizations of asthmatics, but that provided a limited window into the problem, says Betsy Clapp, research analyst for the Multnomah County Health Department. The Regional Equity Atlas 2.0 adds information from asthmatics ages five to 50 who visited a doctor for their asthma or got a prescription for the disease from a pharmacy.
Researchers have long observed high asthma rates among the poor and people of color. Some of that is traced to substandard housing with weak ventilation systems and old carpeting. “The issue is compounded by poor housing conditions, moisture, mold, pests — those are extreme asthma triggers,” says Noelle Dobson, associate director of the Oregon Public Health Institute.
Low-income and minority populations also are more likely to smoke cigarettes and live near high-traffic and industrial areas where air pollution is more acute.
What the maps show
Health analysts knew about 10 percent of Multnomah County residents have asthma, but the new maps revealed census tracts with rates as low as 7.7 percent and others as high as 19 percent, Clapp says.
Some of the highest rates were found along U.S. Highway 30 in Portland’s Linnton and St. Johns neighborhoods, parts of outer east Portland and Gresham, and along the Columbia River. In the suburbs, areas in and around Milwaukie and Oregon City were the highest, plus parts of Hillsboro, Forest Grove, Tualatin, King City and Beaverton.
The maps show high asthma rates for people living near freeways and truck routes such as Highway 30, Highway 99 in Southeast Portland and Highway 224 in Milwaukie. But it’s hard to draw firm conclusions, because some suburban areas along I-5, for example, have lower rates, says Kris Smock, Regional Equity Atlas project manager.
Freeways, childhood asthma linked
In a study of 10 European cities published last spring, scientists concluded 14 percent of chronic childhood asthma was due to exposure to high vehicle traffic on nearby roads, and 15 percent of asthma attacks were caused by air pollution.
A June 2013 study by University of California at San Francisco scientists found that early exposure in infancy to nitrogen oxide, a component of motor vehicle air pollution, is strongly linked to later development of childhood asthma among blacks and Latinos. Researchers concluded that air pollution might be a cause of asthma, and they’re exploring whether exposure to pollution, tobacco smoke and stress can cause chemical changes in DNA — and thus pass along a predisposition to asthma to future generations.
Any serious campaign to reduce asthma requires action on multiple fronts. People can quit smoking. Cities can crack down on slum landlords. TriMet can improve mass transit.
Health can become a greater factor in development reviews.
A Health Impact Analysis in the Bay Area found that a planned multifamily complex next to a freeway could be re-oriented away from traffic and fitted with improved ventilation to reduce tenant exposure to air pollution. A similar analysis is expected if west Hayden Island is developed with marine terminals, to minimize the impact of truck and rail emissions on nearby mobile home park residents.
And trees make a difference. They absorb air pollutants and carbon dioxide, add oxygen to the air and lower temperatures.
Friends of Trees recently planted about 90 trees at Lent Elementary School, located in a low-income East Portland community near I-205 with low tree canopy. A recent experiment in London, England, showed that such small-scale tree plantings can have a marked impact.
Scientists planted 24 young silver birch trees outside houses located next to a busy stretch of highway. Silver birch leaves are covered with microscopic hairs, which are good at trapping tiny particles of pollutants emitted by vehicles. Two weeks later, pollution levels measured inside the neighboring homes fell more than 50 percent.
It’s often hard to measure the impacts of trees because they take so long to grow. But Donovan, the Forest Service economist, found an opportunity to study the impact when a massive amount of trees in 23 states died due to an emerald ash borer infestation. His published study estimated that the lost trees resulted in 15,000 deaths from cardiovascular disease and 6,000 from lower respiratory diseases in those states from 2002 to 2007.
In a 2011 study in Portland, Donovan found that a lack of tree canopy in a neighborhood was associated with low birth weights in babies born to those households. The more trees
located within 50 meters of a home, the less likely a baby from that household would be born underweight.
Planting trees can be one of the most low-cost ways to address air pollution and asthma, Fogarty says, and it’s a great way to engage the community.
“I don’t know if it’s a panacea or anything, but it can’t be discounted.”