Daily Grouped Pollen Concentrations (Trees and Weeds) for Select US Cities, 2003-2024

The National Allergy Bureau™ (NAB™) commonly provides grouped pollen levels. In this dataset, grouped trees and grouped weeds are provided as daily pollen levels and concentrations using data from the NAB. Grouped grass pollen metrics were excluded from selected products to align with data-sharing policies. Public release of grouped grass data could allow inference of taxa-specific concentrations in some contexts; therefore, these metrics are not included.

Daily pollen levels are determined from PPCM concentrations that fall within the following thresholds, which are based on the proportion of days exceeding these PPCM numbers. The pollen levels provided in this dataset correspond to the following grouped pollen concentrations : Grouped Trees Very High: ≥1500 PPCM High: ≥90–1500 PPCM Moderate: ≥15–90 PPCM Low: <15 PPCM

Grouped Weeds Very High: ≥500 PPCM High: ≥50–500 PPCM Moderate: ≥10–50 PPCM Low: <10 PPCM

Pollen dates were converted to a 365-day-of-year format using 2024 as the reference year for all date calculations, which is the last year of pollen data for this release. This dataset is part of a series of pollen datasets from the NAB, processed and standardized by the Division of Environmental Health Science and Practice (DEHSP), National Center for Environmental Health (NCEH), CDC. Further details of the pollen data, including collection, counting, and calculations, can be found here: https://www.mdpi.com/3954654