Updated: 22-04-2024
Source: China Meteorological News Press
Pollen, as a common allergen, tends to trigger allergic reactions in humans. Studies show that 12.3% to 39.8% of the global population is allergic to pollen, and the prevalence is increasing year by year. In fact, climate change-related factors have a significant impact on the growth of allergenic plants and the spread of pollen, which is one of the reasons why the prevalence of pollen allergy is up year by year.
Earlier or extended pollen seasons due to global warming
It has been shown that global warming is significantly and positively correlated with longer pollen season durations and increased pollen loads of a wide range of allergenic plants in the Northern Hemisphere. The duration of the pollen season has increased at 65% of the sites observed, with an average increase of 0.9 days per year. Some studies have speculated that warmer temperatures at the end of this century have advanced the spring pollen season by 10 to 40 days, delayed the end of the period by 5 to 15 days, and lengthened the pollen season of plants that bloom in summer and fall. In this regard, WANG Xueyan, a doctor of the Allergy Treatment Department, Beijing Shijitan Hospital, Capital Medical University (CMU-BSH), said that it is important to pay more attention to the pollen concentration monitoring data in advance and take timely protection.
The figure shows a light microscope photograph of the pollen of Artemisia annua in the genus Artemisia, family Asteraceae.
Source: Pollen Laboratory, Allergy Center,CMU-BSH
Increased CO₂ leads to higher pollen counts
With global warming, the level of carbon dioxide in the atmosphere is rising. CO₂ is an vital nutrient for plant growth. Within a certain range, as CO₂ levels increase, the rate of plant photosynthesis increases, which promotes plant growth and the production of more pollen. However, CO₂ concentrations above a certain level can also lead to a decrease in the rate of photosynthesis, thus affecting plant growth and development.
Pollen concentrations are high in the spring due to blooming flowers.
Greenhouse gases and noxious gases intensify pollen sensitization
As global urbanization continues, the interaction between the increase in airborne particulate matter and greenhouse gases due to the increase in automobile exhaust and harmful gases emitted during industrialization can alter the allergen content of pollen, thus altering its allergenicity as well as the severity of the symptoms it causes. For example, nitrogen oxides from vehicle exhaust can be combined with pollen particles and aggravate allergy symptoms. Some pollutants can even destroy the surface structure of pollen particles, releasing a large number of tiny pollen fragments that can penetrate deep into the lungs and cause great damage.
In addition, along with the increasing urban heat island effect, pollen loads show an increasing trend in urban areas. Studies have shown that ragweed plants in urban areas grow faster, flower earlier and produce more pollen than outside the city. As a result, the proportion of pollen allergy sufferers and the degree of allergy are relatively higher in cities.
Editor: JIANG Zhiqing