By Marisa Naujokas, Ph.D.
Using national-level data, NIEHS-funded researchers reported that changes in the timing of spring onset is linked to increased occurrence of allergic rhinitis, commonly referred to as hay fever, among U.S. adults. The timing of spring onset can be a sensitive indicator of ecosystem responses to climate variability and change. The study was led by Amir Sapkota, Ph.D., associate professor at the University of Maryland School of Public Health in College Park, Maryland.
Hay fever is often triggered by exposure to airborne pollen and mold. It is a chronic condition that affects 25 million Americans, reducing their quality of life and leading to missed work and school days. Hay fever symptoms include sneezing and watery eyes. Symptoms may increase when plants and trees are beginning a new growth season and vegetation is generating increased amounts of pollen and spores.
Using National-Level Satellite and Health Datasets
To study the effects of climate variability and change on the prevalence of allergic rhinitis during 2001-2013, researchers used satellite data collected by NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) to identify the start of spring (SOS) for each county in the contiguous United States. They averaged the 12-year data and calculated how yearly SOS deviated from the 12-year average for each county. They divided yearly deviation in SOS into five categories: very early, early, normal, late, and very late. They linked this SOS deviation with 2002-2013 National Health Interview Survey (NHIS) data based on the NHIS respondent’s county of residence.
How can both early and late onset of spring increase prevalence of hay fever?
- Early SOS: Trees bloom early, leading to early onset and longer pollen season.
- Late SOS: Late onset of spring may mean that many different species of trees are blooming simultaneously, significantly increasing the pollen levels in the environment.
After linking the two datasets – the health survey results and the satellite SOS data – the researchers analyzed whether changes in the timing of SOS were associated with occurrence of hay fever. They found that people living in counties where SOS onset was very early reported a 14% higher occurrence of hay fever compared to those living in counties where onset of spring was within the normal range. Those living in counties with very late onset of SOS also had an 18% increase of hay fever occurrence compared to the reference group. According to the researchers, with about 8% of U.S. adults nationwide reporting hay fever, these increases could affect many people in the U.S. and across the world where trees are a major source of spring pollen.
Implications for Public Health
The researchers point out that previous studies have shown plant phenology (the study of timing of spring onset in plants and other biological events) to be one of the most sensitive indicators of ecological response to ongoing climate change. This study showed that such changes in plant phenology are directly linked to burden of allergic disease. These results raise concerns that the global burden of allergic disease may increase with ongoing climate variability and change.
Given that climate variability is projected to intensify, Sapkota said that such data are critical to inform public health strategies. “Climate change impacts our health in more ways than we can imagine. We need community-specific adaptation strategies to increase resilience and minimize disease burden associated with climate change,” Sapkota said.
Citation: Sapkota A, Murtugudde R, Curriero FC, Upperman CR, Ziska L, Jiang C. 2019. Associations between alteration in plant phenology and hay fever prevalence among US adults: implication for changing climate. PLoS ONE 14(3):e0212010. [Abstract]