Grass Pollen Exposure in the Continental United States: Species Prevalence and Population Patterns
Saturday, February 21, 2015
Exhibit Hall A3 (Convention Center)
Richard K. Lankow, PhD, Murielle Escalmel, Pharm. D., Robert S. Jacobson, Sue C. Hocker, Terrance Coyne, MD
Rationale: Epidemiological studies have shown that pollen from multiple species within the grass family (Poaceae) are major US aeroallergens. A growing body of immunological data document species-specific responses in grass-allergic patients.  Most of the population is exposed to multiple grass species, however there has been no recent update on population exposure by species across the continental US.

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.