Mar 31, 2024 18:00:00

There is a mysterious bacterial infection that spreads when the air is clean.

Ensuring clean air is a global

issue , as air pollution has been shown to not only cause respiratory diseases, but also health problems such as mental health and cognitive function problems, and even male infertility. It has become. A study has found an unexpected link between clean air and a sharp increase in infectious diseases spread by aerosols containing bacteria.

Mysteriously rapid rise in Legionnaires' disease incidence correlates with declining atmospheric sulfur dioxide | PNAS Nexus | Oxford Academic
https://academic.oup.com/pnasnexus/article/3/3/pgae085/7624911

Mysterious, Rapid Surge in Legionnaires' Disease Linked to Cleaner Air : ScienceAlert
https://www.sciencealert.com/mysterious-rapid-surge-in-legionnaires-disease-linked-to-cleaner-air

Legionnaires' disease , also known as 'veteran's disease,' has been rapidly increasing in recent years since a mass outbreak occurred at a veterans' gathering in Philadelphia, USA in 1976, with about 1,100 cases reported in 2000. In 2018, the number of cases increased almost nine times to about 10,000. We are also seeing a similar five- to seven-fold increase in cases in parts of Europe and Canada.

If an air conditioning system becomes contaminated with Legionella, the bacteria that causes Legionnaires' disease, the bacteria can attach to water droplets floating in the air and spread, which can spread the disease. In fact, in past large-scale outbreaks, air conditioners, commercial ventilation systems, and factory cooling towers have been identified as culprits. However, the cause of many sporadic cases of Legionnaires' disease is unknown, and the reasons behind the overall increase in cases are unclear.

A research team led by Fangkun Yu of the State University of New York at Albany set out to investigate the cause, and as a result of analyzing cases reported to the US Centers for Disease Control and Prevention between 1992 and 2019, they found that Legionnaires' disease was prevalent. It turns out that New York state is the worst in the United States.

Therefore, the research team analyzed the incidence of Legionnaires' disease and environmental factors such as humidity, temperature, precipitation, and amount of ultraviolet rays in New York State, but found no association with a long-term increase in Legionnaires' disease.

However, further investigation revealed that the decline in atmospheric sulfur dioxide (SO2) concentrations is occurring at a similar rate to the increase in Legionnaires' disease, meaning that as atmospheric SO2 decreases, reports of Legionnaires' disease increase. was found to be increasing. SO2 is one of the major air pollutants, and along with nitrogen oxides

, it is also known as a cause of acid rain.

Below is a comparison of case reports of Legionnaires' disease in New York State (black ◆) with SO2 concentrations at two points in New York State (blue ● and purple ▲). It can be seen that the increase in Legionnaires' disease and SO2 concentration are symmetrical. Analysis shows that during the same period, the pH of rainwater (pink *) and the pH of droplets from cooling towers (yellow line) also increased, which means that the acidity of water droplets in the air decreased. It was shown.

The research team conducted simulations using a chemical model and confirmed that when SO2 in the atmosphere is absorbed by water droplets, it is converted to sulfuric acid, making the water droplets acidic and making it difficult for Legionella to inhabit. They also found that lower SO2 concentrations recorded at two sites in New York state reduced the acidity of water droplets by at least a factor of 10.

Based on this, the research team concluded that ``As a result of the reduction in SO2 air pollution, the acidity of aerosols emitted from cooling towers decreases, and the survival period of Legionella contained in contaminated droplets is extended, leading to the spread of Legionnaires' disease.'' He proposed the hypothesis that ``may have increased.''

When the research team mapped the locations of Legionnaires' disease outbreaks, they found a significant correlation between where Legionnaires' disease patients lived and the distance from there to cooling towers. Specifically, the risk of hospitalization due to Legionnaires' disease was significantly higher in areas 7.3 km away from cooling towers.

The research team points out that the results of this study only show an association and do not prove causation.

The research team also emphasized that there is no doubt that reducing air pollution is beneficial for public health and the natural environment. It is important to develop strategies to reduce Legionnaires' disease by utilizing