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Tiny air pollution particles have been revealed in the brainstem of young people and are intimately associated with molecular damage related to Alzheimer’s and Parkinson’s disease.
If the pioneering discovery is confirmed by future research, it would have global implications because 90% of the world’s population lives with unsafe air. Medical experts are cautious of the findings, saying that while nanoparticles are a likely cause of the damage, it remains to be seen whether this leads to disease later in life.
There is already good statistical evidence that increased exposure to air pollution increases rates of neurodegenerative diseases, but the importance of the new study is that it shows a possible physical mechanism by which the damage occurs.
The researchers found abundant contaminating nanoparticles in the brainstem of 186 young people from Mexico City who had died suddenly between 11 months and 27 years. They likely reached the brain after being inhaled into the bloodstream or through the nose or intestine.
The nanoparticles were closely associated with abnormal proteins that are characteristic of Alzheimer’s, Parkinson’s, and motor neuron disease. The aberrant proteins were not seen in the brains of people of the same age from less contaminated areas, they said.
What are the best policies to reduce air pollution?
Most of the air pollution is produced by the burning of fossil fuels and waste, and this is the focus of the global recommendations of the World Health Organization:
- Move from coal and gas power plants and diesel generators to solar, wind and hydroelectric power
- Prioritize walking, biking and public transportation over cars in urban areas and switch to electric cars
- Improve the energy efficiency of homes to reduce heating needs and avoid burning coal and wood indoors.
- Promote waste reduction and use incineration only when unavoidable and when emission controls are in place.
- Reduce stubble burning in fields upwind of cities
- Create green spaces in cities to help eliminate some pollutants.
In the UK, extensive government research shows that deterring polluting vehicles from urban and urban centers is by far the fastest and most cost-effective way to reduce levels of nitrogen dioxide pollution, which are at levels illegal in most urban areas.
Other policies include:
- Modernization of buses, heavy vehicles and taxis, which is the next most efficient option
- Scrapping schemes for older, polluting vehicles and subsidies for electric vehicles can also help
What are the best ways to avoid air pollution?
The solution to air pollution is to stop it at the source, but until that happens, experts, including the British Lung Foundation (BLF), suggest the following:
- Avoid spending long periods of time in places where pollution accumulates, such as busy roads.
- If you are traveling by foot or bicycle, using back routes away from congested roads can cut your exposure in half. Even on busy streets, cyclists experience less pollution than drivers
- Some scientists recommend that parents wear covers on their strollers to protect babies.
- Go to work earlier, before rush hour starts and pollution levels have built up
- When air pollution is high and if you have a lung condition like asthma, reduce or avoid strenuous exercise outdoors or exercise indoors
- There is very little evidence to recommend the use of masks, according to BLF
“It’s scary because, even in babies, there is neuropathology in the brain stem,” said Professor Barbara Maher of Lancaster University, UK, and part of the research team. “We can’t prove causation so far, but how can you expect these nanoparticles containing those metal species to settle inert and harmless within critical brain cells? That’s the ultimate proof – seriously, it looks like those nanoparticles are firing the bullets that are causing the observed neurodegenerative damage. “
Maher said the work provides hypotheses that could now be tested. For example, brain stem damage would affect the control of movement and gait in young people and this should correlate with exposure to contamination if nanoparticles are the cause.
The causes of neurodegenerative disease are complex and not fully understood. “There will definitely be genetic factors and it is very likely that there are other neurotoxicants,” Maher said. “But what’s special about air pollution is how often people are exposed. I don’t think human systems have developed any defense mechanisms to protect themselves from nanoparticles. “
He said it was important to study the children, as they have not experienced other factors associated with dementia such as alcohol consumption: “Then they become the canaries in the coal mine.”
The research was directed by Lilian Calderón-Garcidueña from the University of Montana, United States, and is published in the journal Environmental Research. It found that the metal-rich nanoparticles matched the shape and chemical composition of those produced by traffic, through combustion and braking friction, and that they are abundant in the air of Mexico City and many other cities.
Professor Louise Serpell, from the University of Sussex, UK, said that nanoparticles were a plausible cause of brain damage, but that there was not enough evidence that nanoparticles could cause neurodegenerative diseases: “There are many other probable causes of neurodegenerative diseases. . “But she said,” Our environmental exposure to pollution and pathogens is probably very important in triggering disease. “
Jordi Sunyer, doctor of medicine and surgery at the University of Barcelona, said that animal experiments had shown that inhaled nanoparticles could reach the brain and cause damage, but said that inflammatory chemicals caused by air pollution in the lungs could also reach the brain.
The research found the nanoparticles in the black substance, a key area of the brain in Parkinson’s disease. David Dexter, UK associate director of Parkinson’s research, said: “We still don’t fully understand what causes Parkinson’s disease, but this study is based on research that has linked poor air quality and neurodegeneration, as well as links to metal toxicity. Parkinson’s is the fastest growing neurological condition in the world, so [the role of the environment] it’s a really important area in global research. “
But he said: “The pathology in this study is quite different and it is not something that we have seen in our brain bank in typical cases of Parkinson’s.” Maher said this could be because air pollution levels vary between cities.
Dr Susan Kohlhaas, research director at Alzheimer’s Research UK, said: “Air pollution is linked to many adverse health conditions and a growing body of evidence suggests that this includes our risk of developing dementia. Proteins accumulate in the brain years before we see visible symptoms of dementia, but more research is needed before we can suggest that air pollution drives brain changes associated with disease in children. “
Previous work by Maher and his colleagues has shown the nanoparticles in the frontal cortex of the brain and in the heart of young people, while other researchers in China have revealed them in blood.
He said it was critical that action be taken, in particular by measuring the amount of nanoparticles people are exposed to. Typically, only the total weight of particles smaller than 2.5 microns is measured.
“If you measure it and understand where the problem is greatest, then you can start to do something,” he said. “Policy makers need to take these findings into account and actually start to figure out how we can reduce as much of this exposure to air pollution as possible.”
