By Heath Brown 

Pollen, a powdery substance released by trees, grasses, and weeds for reproduction, is almost universally disliked by people because it causes allergic rhinitis, also known as hay fever, which is the inflammation of the inside of the nose. Most people’s allergic responses are triggered in the spring when trees and flowers produce the most pollen. Pollen in the air can also cause sneezing, congestion, watery eyes, and cold-like symptoms. Each year, as many as 81 million Americans suffer from pollen-related seasonal allergies, according to Yale Climate Connections. The scary news is that the pollen season is becoming longer and more intense than in the past.  

Pollen particles drifting into the air from a tree. Photo credit: Essentials collection via iStock Photos.

In their article, the NIEHS reported that the annual average of daily airborne pollen increased by 46% between 1994-2000 and 2001-2010, and the pollen season increased by up to 13-27 days in the northern United States between 1995 and 2009. Climate change is the driving force behind these changes, as scientists have attributed warmer global temperatures to an increase in allergy season length and pollen level. William R. L. Anderegg, an associate professor at the University of Utah, researched pollen trends in North America. He found cases of pollen seasons starting as many as 20 days earlier than they did in the 1990s and reported a 21% increase in pollen concentrations from 1990 to 2018 on the continent.  

Along with warmer temperatures, higher CO2 concentrations and increased precipitation levels are also driving these changes. This is because environments with higher temperatures and CO2 concentrations result in more pollen production per plant, and thunderstorms “break down pollen spores into even smaller pieces, and these pollen spores can then more easily enter the lungs,” according to Brooke Lappe, a doctoral student at Emory University’s Rollins School of Public Health. According to an article from the Royal Meteorological Society, warmer air holds more moisture, boosting the frequency of thunderstorms and the division of pollen spores. 

High pollen counts turn a puddle on the road yellow. Photo credit: Bob Brown via the Richmond Times Dispatch.

Another potential cause of extreme seasonal allergies is cities planting more male than female trees. Pollen is produced by the stamen, a male reproductive organ. Tom Ogren, a horticulturist with a master’s degree in agricultural science and writer of Safe Sex in the Garden, claimed that the over-saturation of male trees and shrubs causes such bad allergy conditions in cities. He argues that putting more female plants in cities, which absorb pollen in the air, would significantly reduce this issue. He also insisted that many cities plant more male than female trees because male trees don’t produce seeds. The idea is that they require less maintenance, because gardeners don’t have to clean up around a tree as much if it’s not dropping seed pods or fruit. Ogren has since become an advocate for implementing less allergenic trees in cities. He developed the Ogren Plant Allergy Scale, which rates plants at 1–10 based on their allergy potential.

However, some people in the agriculture industry do not agree with the claims published by Ogren, such as crop scientist Sarah Taber. According to an article on Slate, Taber argued that planting only male trees is impossible, because only 5% of trees are dioecious, or distinctly male or female. The rest can have both male and female organs. Additionally, Taber doesn’t see planting more female trees as a solution because of how much pollen trees can easily produce. There is also little verifiable evidence that male trees are more prevalent in urban areas than female trees. 

While there are differing opinions on some of the causes of seasonal allergies, there is no question that longer pollen seasons with higher pollen concentrations will cause an increase in the severity of seasonal allergies. Children, the elderly, and people with asthma are generally the most susceptible to developing symptoms due to pollen. Generally, allergic symptoms due to pollen are not that serious in terms of having the potential to do any long-term damage to the body. However, the symptoms are nonetheless very irritating to live with, and it is virtually impossible to avoid pollen, because it is everywhere, especially in the Richmond area. According to an article by Axios Richmond, Richmond consistently ranks as a city with one of the highest annual pollen counts in the country because of its abundance of high pollen-producing trees, such as elm, maple, and oak.

Pollen pilling up on a car. Photo credit: Guilhem Vellut vis Flickr.

I asked three students—Mac Montague (‘25), Charlie Stone (‘25), and Nicolas Crowl (‘25)—about their relationship with pollen. While Montague notices the pollen outside like everyone else during allergy season, he said, “I’m not really that affected by it. I just kind of have to sneeze or blow my nose more if I’m outside for a while.” Pollen is much more disruptive in Stone’s and Crowl’s lives, as they both experience common symptoms of congestion in their throat and watery and itchy eyes. Crowl, who has asthma, said, “I only really notice it during pollen season. I can still play sports and everything, but it affects me more.”  

As a result of pollen allergies being so common, the medical industry for allergy treatment is gigantic. According to the Centers for Disease Control and Prevention, Americans spend over 3 billion dollars on medical costs related to pollen. Pollen has a significant effect on millions and millions of people, and it isn’t going anywhere. In fact, it is probably only going to get worse.