Prolonged exposure to air pollutants, such as nitrogen dioxide and fine particles, may accelerate cognitive decline and increase the number of hospitalizations and mortality from heart attack, indicate two separate studies.
A study published in The Lancet Healthy Longevity shows that air pollution “may delay mental processing, impair memory and cause changes in brain structure in old age, accelerating cognitive decline,” according to the Spanish news agency EFE.
On the other hand, a study by the Spanish Heart Society (SEC) and the Spanish Heart Foundation (FEC) found that pollution increases hospitalizations and mortality from acute myocardial infarction during hospitalization, which on days with high levels can rise by as much as 14%, EFE reports.
In the case of the first study, British citizens born from 1946 were studied, focusing the work on middle-aged adults (45 to 64 years), with their exposure to nitrogen dioxide (NO₂), nitrogen oxides (NOx) and fine particles (PM10 and PM2.5) being assessed.
Suspended particles include mineral and/or organic substances that can be found in the atmosphere in liquid or solid form, with the most harmful to human health being those with an aerodynamic diameter below 10 µm, called PM10, because they can enter the respiratory system, explains the Portuguese Environment Agency.
When the participants were between 69 and 71 years old, their cognitive performance and brain structure were analyzed through memory tests, processing speed tests and brain imaging obtained by magnetic resonance imaging.
The results show that increased exposure to nitrogen dioxide and to particles during midlife is associated with slower mental processing and a decline in cognitive function.
EFE reports that scientists also observed that elevated levels of nitrogen oxides were associated with a reduction in hippocampal volume, while exposure to nitrogen dioxide and to particles was linked to a dilation of brain ventricles, indicators typically associated with cerebral atrophy.
The fact that the investigation reveals new evidence that air pollution has lasting effects on the human brain, beyond the consequences on physical health, reinforces, according to the authors, the need to advance emission-reduction policies as an essential public health strategy to protect long-term brain function.
For the cardiology study, data from 122 hospitals of Spain’s National Health System were analyzed, with environmental monitoring stations located within a 10-kilometre radius and information on 115,071 patients over 18 years old diagnosed with acute myocardial infarction between 2016 and 2021.
The results showed how the concentrations of PM2.5 above 10 micrograms per cubic metre in the three days preceding admission are associated with a significant increase in hospital admissions for acute myocardial infarction, with up to 22 additional heart attacks per 1,000 admissions.
Moreover, when pollution levels are very high and exceed 25 micrograms per cubic metre, the mortality risk increases by 14%, which means that for every 125 people admitted to hospitals, there is approximately one more death than on days with cleaner air, noted Raquel Campuzano, the study’s lead author, cited by EFE.
“These particles [PM2.5 and PM10] can cause inflammation in the body, alter the functioning of blood vessels and increase the risk of clots,” effects that “are directly related to the progression of atherosclerosis (hardening and narrowing of the arteries) and to the rupture of plaques that form in them, which can trigger serious events, such as a heart attack,” warned Jordi Bañeras, coauthor of the study.
