In Asthma, Blog, Science

As we learned in our two-part series Whats Triggering Your Asthma, one common trigger of asthma is pollen. However, how pollen actually triggers asthma continues to be a mystery. Ten years ago, Dr. Richard C. Flagan, a chemical engineering professor at Caltech, set out to change that by conducting an interdisciplinary study on the relationship between asthma and pollen. The study ranged from aerosol processes to botany, kinetic particle theory, and meteorology.

Dr. Flagan, like many researchers before him, noted that “an asthma attack occurs when the bronchial tubes [the pipes connecting your windpipe with your lungs] and the bronchioles [the very little tubes that connect with the alveoli, where your blood absorbs oxygen from the air]…constrict due to some kind of irritation,” but “pollen grains are too big to penetrate deep into the respiratory system” where asthma is caused. Nevertheless, asthmatics worldwide suffer every growing season.

How does pollen get in?

Pollen is how plants reproduce. Some plants have sticky pollen that attaches to pollinating animals. However, the plants that most commonly trigger seasonal allergies and asthma are those whose pollen “have evolved to disperse in a gentle wind.” The first breakthrough game when two researchers at the University of Melbourne looked at what happens when you put pollen in water. They found that it underwent a process called osmotic shock: water enters the pollen grains “increasing the pressure until they burst like overfilled water balloons.” There are many ways pollen can become wet and rupture in nature, such as when it rains or from the morning dew after high-humidity nights. 

Pollen counts are a common metric that alert people when to worry about hay fever. While hay fever is a relatively minor disease, it can contribute to asthma. An important discovery Dr. Flagan made is that even weeks after winds swept away the pollen-generating flowers, his team’s rooftop pollen detector recorded significant levels of pollen fragments “two days after nighttime humidity rose about 80 percent.” Therefore, a low pollen count does not necessarily mean that asthmatics are safe from the effects of airborne pollen.

Thunderstorm Asthma

One additional mechanism through which vegetative reproductive material finds its way into your respiratory system is through thunderstorms. Empirical evidence has suggested a link between thunderstorms and asthma epidemics since the night of June 24, 1994. When thousands of patients — ten times the normal amount — descended upon English emergency rooms. The apparent cause: the summer storms that had just rolled through. The phenomenon persists, killing nine people in Australia last November and another five in Kuwait last December.

Thunderstorm asthma is thought to be caused by pollen molecules being broken up and more easily inhaled.

Photo by John Fowler

Dr. Flagan’s findings allowed him to attach a hypothesis to this previously inexplicable correlation. First, dry updrafts pull the pollen grains into the clouds, where the high humidity ruptures them. Downdrafts then bring these pollen fragments, primed to wreak havoc on asthmatics’ lungs thanks to their microscopic size. Furthermore, the electric charges that build up during thunderstorms may help the pollen rupture, exacerbating the situation.

We’re not saying that you should be scared of every thunderstorm or disregard pollen counts. Rather, you should recognize the many triggers that affect the millions of asthmatics worldwide every day, be they yourself, your loved ones, or your friends.

Thankfully, many researchers are working hard to minimize the risk of these triggers. Here at Exhale, we have developed the only proven and patented solution for detecting allergens that trigger allergies and asthma in the home. Exhale detects the pollen fragments, which, as we just learned, can persist outside of pollen season and be particularly harmful to asthmatics. Completing an Exhale analysis will help you know what is triggering your asthma.

Julius Reiner

Julius is currently a student at Brown University.
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