Foresters rarely make headlines. But this February, the U.S. Forest Service's two lone urban forest researchers in Portland—Sarah Jovan and Geoffrey Donovan—pretty much turned the city upside down.

After testing local moss for pollutants, the pair found strikingly high levels of the carcinogenic heavy metal cadmium near Brooklyn-neighborhood glassmaker Bullseye Glass.

"It wasn't a joyful day," Jovan says. "It looked like a bullseye over Bullseye."

The findings ignited a citywide firestorm of debate about lax regulation of the art glass industry. But the most lastingly significant thing in the study might be the ingenious new way Jovan and Donovan devised to measure urban pollution. The standard devices used to measure air quality are extremely expensive to operate. But Jovan's and Donovan's solution was cheap and simple. The pair collected 346 moss samples from streets and yards all over Portland—just half a gram, less than the weight of a paper clip—and then tested them for toxins. Though it's well-established science in the world of forestry that moss and lichen absorb air pollutants, few had thought to apply that knowledge to moss growing in an urban area.

(Emma Browne)
(Emma Browne)

Jovan and Donovan aren't done finding disturbing air quality results in town. Now they're turning their attention from cadmium to lead. The initial results suggest they will ignite another explosive policy debate, this time over the demolition of old houses. The highest concentration of lead they've identified so far was across from a lot where a house had been demolished six months prior. Testing is under way to identify the source of the lead—paint or gasoline or some other source. But either way, the findings may have a lasting impact on Portland's fight over demolition of old homes.

The two forest researchers also plan to apply their new method of pollution testing in other cities.

"It was disastrous there for a bit with the findings," says Jovan. "But on the other hand, the moss really served a very useful purpose."