Eve, here. I hope some of you found this post about the dangers of PM2.5 pollution useful. One of the main reasons I live in a notorious coastal city rather than glamorous Bangkok is because of the air quality. Prevailing winds blow from the sea for more than nine months of the year, and PM2.5 levels are low. Even when it’s not, it’s sometimes hot enough to require air conditioning at least once in a while. So it’s not that difficult to keep the windows closed and the air filter on.
IQ Air provides a map of air quality readings updated hourly, even in secondary cities, so you can know what your hood is like if you don’t want to miss out on a PM2.5 monitor. From the area where I live (today the situation is worse than a week ago when most stations were green; we are in the high season, there is a lot of traffic, and there is also an increase in the period when crops are burned). You can see that the grain size is quite fine.
You can also zoom in. This one is even bigger. A small arrow indicates that the wind is blowing from the sea. Due to the proximity of one monitoring post, these maps provide a good approximation.
In fact, at urban heights (high-rise buildings), PM2.5 increases with altitude, so being on a high floor doesn’t really benefit you.
Now on to the main event.
Written by Paula Spann. The original article was published in KFF Health News.
The two patients had been coming to the Penn Memory Center at the University of Pennsylvania for years. There, doctors and researchers observe people with cognitive impairment and groups with normal cognition, depending on their age. Both male and female patients had agreed to donate their brains postmortem for further research. “It’s a wonderful gift,” said Edward Lee, a neuropathologist who heads the brain bank at the university’s Perelman School of Medicine. “They were both passionate about helping us understand Alzheimer’s disease.”
The man, who died of dementia at age 83, lived in Philadelphia’s Center City neighborhood with a hired caregiver. An autopsy revealed amyloid plaques and tau tangles, proteins associated with Alzheimer’s disease, spread throughout the brain.
Researchers also found infarcts, small patches of damaged tissue, indicating he had suffered several strokes.
In contrast, the woman, who was 84 when she died from a brain tumor, “had very few symptoms of Alzheimer’s disease,” Lee said. “We tested her every year and she didn’t have any cognitive problems.”
The man lived a few blocks from Interstate 676, which runs through downtown Philadelphia. The woman lived a few miles away in the suburbs of Gladwyne, Pennsylvania, surrounded by woods and country clubs.
The amount of air pollution she was exposed to, specifically the level of fine particulate matter called PM2.5, was less than half what she was exposed to. Was it a coincidence that he developed severe Alzheimer’s disease while she was cognitively normal?
There is growing evidence that chronic exposure to the neurotoxin PM2.5 not only damages the lungs and heart, but is also linked to dementia, but this is probably not the case.
“The air quality you live in affects your cognition,” said Lee, lead author of a recent paper in JAMA Neurology. The paper is one of several large-scale studies conducted in the past few months to demonstrate the link between PM2.5 and dementia.
Scientists have been tracking this relationship for at least a decade. In 2020, the influential Lancet Commission added air pollution to its list of modifiable risk factors for dementia, along with common problems such as hearing loss, diabetes, smoking and high blood pressure.
But these findings come as the federal government seeks to dismantle the previous administration’s efforts to continue reducing air pollution by transitioning from fossil fuels to renewable energy sources.
“‘Drill, baby, drill’ is just the wrong approach,” said John Balmes, a spokesman for the American Lung Association, which studies the health effects of air pollution at the University of California, San Francisco.
“All these actions reduce air quality and lead to increased mortality and disease, and dementia is one of the consequences,” Balmes said, referring to recent environmental action by the White House.
Of course, many factors can cause dementia. However, the role of particles, which are microscopic solids and water droplets in the air, is being investigated more closely.
Particulates come from a variety of sources, including emissions from power plants and home heating, industrial exhaust, vehicle exhaust, and even wildfire smoke.
Of several particle sizes, PM2.5 is one of the smallest and therefore “appears to have the most negative impact on human health,” Lee said. The particles are easily inhaled, enter the bloodstream, and circulate throughout the body. They can also travel directly from the nose to the brain.
The University of Pennsylvania study was the largest autopsy study of dementia patients to date, involving more than 600 brains donated over a 20-year period.
Previous research on pollution and dementia has relied primarily on epidemiological studies to establish a link. Now, “we’re linking what we’re actually seeing in the brain to exposure to pollutants,” Lee said, adding, “We can look deeper.”
Participants in the study took cognitive tests on PenMemory over a number of years. Using environmental databases, researchers were able to calculate PM2.5 exposure based on home address.
Scientists have also devised a matrix to measure how severely Alzheimer’s disease and other dementias have damaged donor brains.
Lee’s team concluded that “the greater the exposure to PM2.5, the greater the severity of Alzheimer’s disease.” Donors who lived in areas with high PM2.5 levels were almost 20% more likely to develop more severe Alzheimer’s disease at autopsy.
Another related research team recently reported a link between PM2.5 exposure and Lewy body dementia, which ranges from dementia to Parkinson’s disease. Generally considered the second most common type of dementia after Alzheimer’s disease, Lewy body dementia accounts for an estimated 5% to 15% of dementia cases.
In what researchers believe is the largest epidemiological study of pollution and dementia to date, they analyzed the records of more than 56 million traditional Medicare beneficiaries from 2000 to 2014, comparing first hospitalizations for neurodegenerative diseases and exposure to PM2.5 by ZIP code.
“Chronic PM2.5 exposure was associated with hospitalization for Lewy body dementia,” said study author Xiao Wu, a biostatistician at Columbia University’s Mailman School of Public Health.
After adjusting for socioeconomic and other differences, the researchers found that U.S. counties with the lowest PM2.5 concentrations had 12% higher rates of Lewy body hospitalizations than those with the lowest concentrations.
To test their findings, the researchers administered PM2.5 nasally to laboratory mice, and after 10 months they saw “obvious dementia-like deficits,” lead author Xiaobo Mao, a neuroscientist at the Johns Hopkins University School of Medicine, wrote in an email.
The mice got lost in the maze they ran through earlier. They previously built nests quickly and compactly. Now their efforts were sloppy and unorganized. Mao Zedong said autopsies showed their brains were atrophied and had accumulated a protein called alpha-synuclein, which is related to Lewy bodies in the human brain.
The third analysis, published this summer in The Lancet, included 32 studies conducted in Europe, North America, Asia and Australia. They also found that “diagnosis of dementia was significantly associated with long-term exposure to PM2.5 and certain other pollutants.”
Whether dementia due to inflammation or other physiological causes awaits the next round of research, so-called ambient air pollution (the outdoor kind) will increase.
Air pollution in the United States has been declining for more than two decades, but scientists are calling for stronger policies to promote cleaner air. “People argue that air quality costs money,” Lee said. “That’s dementia care.”
But President Donald Trump returned to office pledging to increase the extraction and use of fossil fuels and block the transition to renewable energy. Balmes noted that the administration has rescinded tax incentives for solar power generation equipment and electric vehicles, adding: “The government is encouraging us to continue burning coal to generate electricity.”
The administration halted construction of new offshore wind farms, announced oil and gas drilling in Alaska’s Arctic National Wildlife Refuge, and moved to block California’s plan to transition to electric vehicles by 2035 (the state is challenging the case in court).
“If policies go in the opposite direction and air pollution increases, it will pose a major health risk to older people,” Wu said.
Last year, under the Biden administration, the Environmental Protection Agency set stricter annual standards for PM2.5, noting that “available scientific evidence and technical information indicate that current standards may be insufficient to protect the public health and welfare as required by the Clean Air Act.”
In March, EPA’s new chair announced that the agency would “reconsider” these more stringent standards.
