Two University of Minnesota researchers propose that the rapid spread of Phragmites australis around urban areas could be responsible for high levels of allergenic pollen. Currently most people are simply tested for allergies to grass pollen without differentiating different species of grasses, but since Phragmites pollen is a distinctive size, the authors propose setting up pollen traps to see how abundant the pollen is compared to other grass pollens. More than 90 million people could live close to large stands of Phragmites in the U.S.
Schimpf, D. J. and White, N. A. 2011. Did Cryptic Invasion of North America by Common Reed Change Exposure to Pollen Allergens? University of Minnesota Duluth Occasional Papers. http://d-commons.d.umn.edu:8180/jspui/handle/10792/135