氣候變遷如何加劇花粉過敏

As climate change continues to affect our planet, one of the significant impacts is on pollen allergies. Rising temperatures are causing longer pollen seasons, which means that people who suffer from allergies are experiencing more severe symptoms for extended periods. Experts have noted that global warming is not only increasing the amount of pollen in the air but also leading to extreme allergy events. A notable example of this occurred in Melbourne, Australia, on November 21, 2016, when a phenomenon known as 'thunderstorm asthma' struck the city. During this event, a storm lifted trillions of pollen particles into the clouds, where they were broken down by rain and lightning into smaller fragments. These fragments then fell back to the ground, making it easy for people to breathe them in. The result was catastrophic, with emergency services overwhelmed by the number of people struggling to breathe. Hospitals were flooded with patients, and tragically, ten people lost their lives, including a woman who died on her lawn while waiting for help. One survivor described the experience as surreal, stating that he went from breathing normally to gasping for air in just half an hour. Paul Beggs, an environmental health scientist, recalled the event as unprecedented and catastrophic, highlighting the confusion among medical professionals who were unprepared for such a sudden spike in asthma cases. Thunderstorm asthma occurs when storms mix pollen with rain and wind, creating a situation where even those without a history of asthma can experience severe allergic reactions. The strong winds associated with thunderstorms can lift pollen high into the atmosphere, where moisture in the clouds breaks it down into smaller, more easily inhaled particles. This event in Melbourne serves as a stark reminder of how climate change is altering the patterns of pollen and the allergies they cause. As temperatures rise, many regions, particularly in the United States and Australia, are seeing an increase in seasonal allergies, with symptoms becoming more severe. This year, pollen levels in the U. S. have been notably high, and experts warn that this trend is likely to continue. Pollen is a natural part of our environment, essential for plant reproduction. While some plants rely on insects to spread their pollen, many trees, grasses, and weeds depend on the wind, releasing vast amounts of pollen into the air. When pollen enters our bodies, our immune systems can mistakenly identify it as a threat, leading to allergic reactions. Common symptoms include sneezing, itchy eyes, and a runny nose, but in severe cases, it can cause breathing difficulties. Since 1984, there have been several recorded instances of thunderstorm asthma, and similar events have occurred worldwide, from the UK to the U. S. Although these occurrences are still relatively rare, climate change is increasing the likelihood of such incidents due to its impact on weather patterns, including storms. While it is challenging to determine the exact influence of climate change on the 2016 Melbourne event, experts like Beggs believe it played a role. They know that climate change is altering the timing and types of pollen we encounter. Research is ongoing to understand how thunderstorms can trigger or worsen asthma. One leading theory suggests that the cold air downdrafts during storms create strong winds that can carry pollen into the storm system. Once there, moisture causes the pollen to break apart, significantly increasing the number of allergenic particles in the air. Studies indicate that pollen levels tend to spike after thunderstorms, which can pose a risk to those with allergies. Fortunately, major thunderstorm asthma events remain rare, but climate change is increasing the risk of pollen exposure in other ways. For instance, warmer temperatures are causing pollen seasons to start earlier and last longer. Elaine Fuertes, a public health scientist, explains that this means people will experience allergy symptoms for a more extended period each year. Ragweed, a common allergenic plant, is particularly problematic in the U. S. and Europe. A single ragweed plant can produce an astonishing amount of pollen, and studies have shown that ragweed pollen seasons are lengthening. For example, in some cities, the pollen season has increased by as much as 25 days. This extended exposure to pollen is concerning, especially if greenhouse gas emissions are not reduced. A study from 2022 predicts that by the end of the century, people may experience even more allergy symptoms than they do now. In some regions, efforts are underway to control ragweed populations due to their significant contribution to pollen allergies. In the past, cities in the U. S. even paid people to cut down ragweed plants to reduce pollen levels, which proved effective. Today, similar initiatives are being implemented in Europe, where workers are actively removing ragweed from urban areas. Another approach to mitigating pollen allergies is to plant tree species that produce less allergenic pollen. Monitoring pollen levels is also crucial for public health. Scientists emphasize the need for accurate information about airborne allergens, as many people are unaware of the pollen levels in their area. While we can easily access weather data, pollen counts are not as readily available. Experts warn that without coordinated action to address climate change, the impact on pollen allergies will only worsen. This could lead to more severe events like thunderstorm asthma and an increase in the number of people suffering from allergies each year.