Extreme heat events are associated with increased hay fever prevalence


Published online: November 8, 2016

Warmer temperatures can alter seasonality of pollen, and may impact allergic diseases such as hay fever. Hay fever affects 17.6 million (7.5%) US adults, impacts quality of life, and results in over $11 billion in medical expenses annually. Extreme heat events will likely increase in frequency, intensity, and duration in coming decades due to changing climate. The potential impact of these increases on allergic diseases is a growing concern.

In this study published in The Journal of Allergy and Clinical Immunology: In Practice, Upperman and colleagues used 1997-2013 National Health Interview Survey (NHIS) data for US adults to explore the association between exposures to increased frequency of extreme heat events and self-reported hay fever. Extreme heat events on the County level were identified by comparing the daily maximum temperature (Tmax) to the county and calendar month specific thresholds (95th percentile of Tmax values) that were calculated based on 30 years of baseline data (1960-1989). The cumulative number of extreme heat events was assigned to each NHIS respondent for the 12 month window preceding survey participation. Association with hay fever was assessed by age, race/ethnicity, sex, education level, poverty status, and urban/rural residence.

Overall, 8.4% of adults aged 18 years and older had hay fever during the period 1997-2013. Hay fever was more common in women than men, in non-Hispanic white and black adults compared to Hispanic adults, in older adults, and among those with higher education and income. Adults in the highest quartile of exposure to extreme heat events had a 7% increased odds of hay fever compared to those in the lowest quartile of exposure.  This relationship was more pronounced for extreme heat events that occurred during spring season, with evidence of an exposure-response relationship.

Among a nationally representative sample of US adults from 1997-2013, exposure to extreme heat events was associated with increased prevalence of hay fever. The findings were more pronounced for springtime extreme heat events. These results provide empirical evidence of how extreme heat events, projected to increase in frequency, duration and intensity in the future, may adversely impact allergic disease among US adults.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

Close-up of pine tree branches in Winter Close-up of pine tree branches in Winter