Heavy Rain Raises Concerns Over Flooding and Landslides. But What If This Weather Affects Respiratory Health?
Clarifying the Connection
Scientists are currently clarifying the link, drawing a close connection between extreme rainfall, which is becoming more frequent and intense due to climate change, and an increase in mortality rates from respiratory diseases. While further research is needed to clarify this connection, it is significant for individuals with asthma and similar conditions.
In a February article published in the journal Nature Sustainability, researchers examined the relationship between respiratory mortality rates and extreme rainfall in 30 cities across East Asia. They found that rainfall with an intensity expected every 5 to 10 years was significantly associated with an increased risk of death from respiratory diseases compared to days without heavy rainfall. The strongest correlation was with asthma, followed by chronic obstructive pulmonary disease. However, there was no significant association with pneumonia.
Extreme rainfall is believed to be linked to respiratory health. (Source: Reuters)
In Japan, research conducted in cities such as Sapporo, Sendai, Tokyo, Nagoya, Osaka, Kitakyushu, and Fukuoka found that for rainfall with an intensity expected every 5 years, there were approximately 3.08 to 5.38 respiratory deaths per 10,000 people from 1980 to 2020. This study did not account for the impact of heavy rain on respiratory health without mortality.
Mr. Cheng He, a postdoctoral researcher at the Helmholtz Munich Health Research Institute and the lead author of the study, stated: “We found a significant correlation between extreme rainfall events and respiratory mortality rates in these cities in Japan, and the impact may last more than 3 to 4 days.”
Similar mortality rates were found in cities in China, Taiwan (China), and South Korea. Researchers also discovered that the risk of respiratory mortality was particularly pronounced among those aged 65 and older, which is a significant concern for Japan due to its aging population.
According to the Japan Meteorological Agency, in 2020, the frequency of heavy rainfall from linear rainbands was 2.2 times higher than it was 45 years prior. Climate change is the driving factor behind this change.
In fact, five organizations in Japan, including Kyoto University, are researching weather modification techniques to prevent heavy rain, including the exploration of dry ice as a means to disrupt air and moisture flow in linear rainbands.
A study led by the University of Tsukuba indicates that Japan also faces threats from “atmospheric rivers.” Due to climate change, corridors of concentrated moisture in the atmosphere are expected to bring record rainfall, especially on the southwestern slopes of the Japanese Alps. Atmospheric rivers may play a role in the formation of linear rainbands, which were linked to extreme rainfall in Hiroshima in 2014, western Japan in 2018, and Tohoku in August 2022.
From Awareness to Warning
While scientists have begun to observe the correlation between extreme rainfall and respiratory health, the biological mechanisms linking the two are still not well understood. However, researchers have identified several plausible explanations: abrupt drops in atmospheric pressure; large daily temperature fluctuations during heavy rainfall; coinciding thunderstorms and high pollen counts; contamination of drinking water and food; as well as power outages disrupting the use of essential devices like ventilators.
Increased humidity can also promote the growth of bacteria and mold, as well as cause constriction of the upper respiratory capillaries. While light rain may reduce pollen counts, heavy rain can increase them by breaking pollen clusters into smaller particles, allowing for better dispersion. Thunderstorm formation can lift particles into the clouds, and once they absorb water, they swell and burst.
Indeed, some of these proposed mechanisms are supported by anecdotal evidence from asthma sufferers, some of whom have reported experiencing attacks triggered by thunderstorms, with one such storm in Melbourne in 2016 leading to a 672% increase in asthma-related hospitalizations.
For Professor He, studies like his emphasize the need for healthcare systems to incorporate weather forecasts into their planning and the importance of community-level efforts to educate vulnerable populations about the risks posed by extreme rainfall and flooding.
However, it also underscores a fundamental point about climate change: its impacts extend beyond high temperatures. “Many people think that climate change is just about average temperature changes, but in reality, all kinds of different extreme phenomena are also related to climate change,” He stated.
According to Professor Hidenori Kage from the University of Tokyo, currently, doctors can only try to help patients understand that the findings of the study are likely to occur, even though there is still a lack of convincing evidence regarding the nature of the biological link. But if such evidence emerges, these insights could be incorporated into official medical guidelines.
