About 30 people came to learn whether their air is safe to breathe last night in North Portland, where the Oregon Department of Environmental Quality held the second of four information sessions about toxic air pollutionin the metropolitan area.
But at the end of the two-hour session, the answer was still unclear. So, a woman in the audience asked DEQ air quality expert Sarah Armitage directly.
“It could be much better,” Armitage answered. “I see levels of risk from a lot of sources that are still not acceptable.”
Armitage presented the findings from a new set of models DEQ created to illustrate which toxic air pollutants are reaching levels that pose health risks – and where. The models took data from DEQ permits, Metro transportation records, the U.S. Census and air monitoring stations to map the presence of 19 different pollutants that are known to increase the risk of diseases including cancer. Then DEQ held the models up to a very conservative health benchmark to see which ones are posing the most risk.
The resulting maps show that the risk from some toxins depends on where you live while other risks are almost universal across the metropolitan area.
But it's not certain that the air – even in the deep red sections of these maps – is unsafe to breathe. The pollutants in question are not regulated directly under the Clean Air Act. Hence, “there are no federal standards for this whole huge family of toxics,” Armitage said.
The family includes pollutants such as benzene and diesel soot that come from cars and trucks burning fuel; 15 polycyclic aromatic hydrocarbons (PAH) and acrolein from burning wood; and cadmium and manganese from metal refineries. Benzene is a known carcinogen according to the Environmental Protection Agency. PAH, cadmium and many others on the list are “probable carcinogens.” Studies show breathing acrolein and diesel soot raise the risk of respiratory diseases.
DEQ found 15 of the 19 toxic pollutants modeled above the health benchmark. Armitage said there are still unknowns when it comes to the levels at which these “toxics” become a health risk.
“But we know they’re around and could do harm,” she said.
Almost all the information in the recently released air toxics report comes from models, as opposed to air monitoring equipment that actually tests the air, Armitage explained. The model takes information DEQ has accumulated about which kinds of industries and pollution sources are operating where, accounts for weather and topography and estimates the concentrations of air pollutants.
DEQ has one air monitoring station in Northeast Portland that costs $150,000 a year to operate. Armitage said it would be nice to have more stations actually testing air quality, but that would be too expensive.
So, DEQ took the models of toxic air pollutants and compared them with a health benchmark of 1 case of illness per 1 million people.
Eight of the 19 toxins modeled at more than 10 times over that benchmark. That means they could cause 10 cases of illness for every 1 million people breathing the polluted air (the Portland metro area is home around 2.2 million people, according to the 2010 U.S. Census).
“One in a million is a very low level of risk,” Armitage said. “Our benchmarks are quite protective. … Going over that is an indication that you’re getting to a position that could be unsafe. But it doesn’t necessarily mean you’re in trouble.”
There’s also the fact that the model is set to project toxic pollution in 2017. It’s not a measurement of the current state of air quality.
“The model is really a 2017 estimate,” said Armitage. “What this really gave us was a new understanding of the region. We have quite a good idea of what pollutants are above our benchmarks, where they are distributed and what we can do about them.”
Among the DEQ findings Armitage noted:
- There’s a tie for worst toxic air pollution offender between wood smoke and exhaust from cars and trucks.
- Benzene “really is everywhere, but we also saw it in patterns near the major highways.”
- 15 PAH “is distributed region-wide. There’s a uniform layer of it across the region.”
- Heavy metals were more neighborhood-based in “a very tight configuration around industry.”
- Hispanic and Latino populations were found to be at the highest risk from toxic air pollution because of residential wood-burning.
- 2 percent of homes in the metropolitan area are heated with wood, and air quality impacts from wood stoves “can be very local” – varying from block to block.
- People within 500 yards of heavily traveled roadways are at a higher risk from many toxins. “What we're seeing is a pattern of high concentrations within 500 yards of heavily traveled roadways.” The levels fall off around roadways “like a bell curve."