The results of the 2022 update of the World Health Organization (WHO) air quality database revealed that practically the entire population of the planet (99%) breathes polluted air, a factor that has been associated with the appearance of cardiovascular and respiratory diseases, among other health problems. Now a new study has found that continued exposure to urban air pollution is linked to an increased risk of developing dementia and Alzheimer’s.
The research has been carried out by scientists from Emory University (Atlanta, USA) and has been published in The Journal of the Alzheimer Association. The authors of the work highlight in the article that “growing evidence indicates that exposure, specifically, to fine particulate matter (PM2.5) plays a crucial role in the pathogenesis of Alzheimer’s and other related dementias.”
It is estimated that in the United States more than six million people suffer from Alzheimer’s, while in Spain this neurodegenerative disease affects around one million people. Experts also warn that 80% of cases in which Alzheimer’s symptoms are still mild are undiagnosed.
PM2.5 fine particles and other toxins in the air we breathe
The air that citizens breathe contains numerous gases such as oxygen, carbon dioxide, nitrogen, carbon monoxide, methane, or sulfur dioxide, as well as microparticles that are in solid or liquid form from dust, ashes, soot, metal or cement particles, among others. These particles can be divided into two groups based on their size: the largest, which are equal to or less than 10 µm or 10 micrometers, called PM10, and the smallest, PM2.5, which are less than or equal to 2. .5 micrometers, “100 times thinner than a human hair,” say the experts.
Long-term exposure to PM2.5 particles is significantly associated with a high incidence of dementia or Alzheimer’s
Mortality related to PM2.5 particles had until now been related to “cardiorespiratory causes” associated with black and organic carbon, and the new data adds different brain disorders. “The importance and significance of this study lies not only in the enormous size of the population sample, which includes millions of people from all over the United States, but also in the individual analysis of the effect of its main chemical components; Among them, black carbon, organic matter, sulfates and inorganic ammonium stand out as those with the highest risk associated with these neurodegenerative diseases”, explained Víctor Briz, senior postdoctoral researcher specializing in neuroscience at the Severo Ochoa Center for Molecular Biology, UAM. -CSIC, in statements to the Science Media Center Spain.
Emory researchers have focused on microparticles of black carbon, nitrogen, sulfates, and ammonium, although the most harmful to both the respiratory system and the brain are the particles that come from burning fossil fuels and are also They are called black carbon. The results of the work reveal that “for each increase of 1 microgram per cubic meter, the risk levels of dementia were 1,123”.
The black carbon that pollutes the air is also associated with respiratory diseases, cardiovascular diseases and cancer. According to the WHO, an estimated 4.2 million deaths a year are related to outdoor air pollution. In 2021, this body also pointed out that 90% of deaths related to PM2.5 particles could be avoided by adopting new guidelines and changed the recommended limits on pollution levels.
PM 2.5 particles are considered the most dangerous pollutant for humans and until now the WHO recommended less than 25 micrograms per cubic meter of air in one day, and the new recommendation reduces the optimal level to 15 micrograms, while PM10 passes from 50 micrograms to 45 per cubic meter of air.
The Emory researchers conclude that “long-term exposure to PM2.5 particles is significantly associated with elevated incidence of dementia or Alzheimer’s.” Briz adds that “this study reinforces previous epidemiological work on the significant risk of developing dementia and Alzheimer’s after continued exposure to environmental pollution.”