Methods: US Census data released in April, 2012 provided data on the population of each county in the continental US. The US Plants Database (USDA) provided data on the county-level prevalence of the grass species studied. Plant prevalence and population data were correlated to examine the potential exposure of people to different allergenic grass species.
Results: Within the US, 84% of the population is potentially exposed to Lolium perenne (perennial rye grass) 75% to Dactylis glomerata (Orchard grass), 69% to Phleum pratense (Timothy grass), and 68% to Poa pratensis (Kentucky bluegrass). Geographic regions showed distinct exposure patterns. As examples, across the southeastern US, Lolium perenne dominates with 81% of the population exposed followed by 43% to Dactylis glomerata. Exposure in the Northwestern US was more heterogeneous with 99% of the population exposed to Poa pratensis, 95% to Lolium perenne and 94% to Dactylis glomerata. The highly populated East Central region was similarly heterogeneous with 99% exposed to Poa pratensis, 98% to Dactylis glomerata, 94% to Phleum pratense, and 87% to Lolium perenne.
Conclusions: Knowledge of distinct regional patterns of exposure can help clinicians to interpret patient history and diagnostic information and to plan therapeutic interventions.