Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff, Lauren Vogel bomb here. When we think of air pollution, we usually think of black clouds pouring out of smoke stacks or the unsightly brown haze that hangs over many of the world's cities. But in recent years, scientists have found increasing evidence of health risks from a part of air pollution that we don't see and that isn't yet
regulated under federal air quality standards. In addition to visible emissions, the burning of fossil fuels and other types of combustions create vast quantities of ultrafying particles somewhere around a thousand of the width of a human hair, that we inhale without ever realizing it. We spoke with Bart Astro, former chief of Air Pollution Epidemiology for the California Environmental Protection Agency and currently a researcher at University of California Davis.
He said that ultrafined particles come from an array of sources. They're emitted from vehicles, especially ones that burned diesel fuel, as well as smaller g selene burning engines such as the ones in lawnmowers and leafblowers, but other types of burning wood, fires, burning leaves, and secondhand smoke from cigarettes, for example, also produce ultrafine particles. So does cooking meat
on the stove in your kitchen. Nevertheless, it's a challenge to figure out the extent of our exposure to ultrafine particles. Because the particles are so small and so transient, they quickly disperse or else coagulate into bigger particles. They're a type of air pollution that is especially difficult to measure.
Astro said. Ultrafine particles are very high in concentration next to roadways, for example, but if you go three hundred to five hundred yards away, that's about two hundred and fifty to four fifty the ultrafines go down to almost background levels. In recent years, scientists at University of California, Davis have developed sophisticated modeling methods that combine sensing data with knowledge about how chemical processes and meteorological conditions affect
these particles. That's allowed them to predict concentrations over several years, which in turn makes it easier to study the particles effects on human health. Austro was the lead author on a study published in twenty fifteen The combined such modeling with health data on one hundred thousand middle aged female teachers and administrators that were recruited from the State Teachers Retirement System. It found an association between ultrafined particles and
death from heart disease Since then. Seventeen study also found that long term exposure to ultrafine particles around highways was associated with cardiovascular diseases and hypertension, and eighteen study in the journal Environmental Pollution suggests that simply moving a bus stop forty to fifty away from an intersection that's about a hundred and thirty and fifty feet can substantially reduce
transit users exposure to high levels of ultrafined particles. It may seem strange that something so small could be so dangerous, but because of their size, ultrafine particles have an easier time getting into lung tissue and causing inflammation. Research has found that even a brief amount of ultrafine particle exposure can increase the allergic inflammation that makes asthma worse. But
that's not the only worry. Ultrafine particles are so tiny that they can penetrate the blood brain barrier and be absorbed in into brain tissue. Recent research suggests a possible link between the tiny particles and Alzheimer's disease and other forms of dementia. Scientists also have found that mice exposed to ultrafine particles early in life had changes in their brains that bore resemblance to those set in humans with
autism and schizophrenia. Despite all that, federal air pollution standards don't yet set limits for ultrafined particles due to the developing state of the scientific evidence about their health effects and the current limitations on monitoring technology, but Ostro says there are some measures that people can take to protect
themselves from ultrafine particles. If you have pre existing conditions such as cardiovascular or respiratory diseases, it's a good idea, for example, to limit your exposure to emissions such as diesel fumes, car exhaust, and any sort of burning biomass. And even if you're healthy, you'll probably want to avoid such exposure as well, which means shifting your running routes away from major roadways is a really good idea. Today's episode was written by Patrick Jake Tiger and produced by
Tristan McNeil. And Tyler Clang. For more on this and other topics. To help you breathe a little easier, visit our home planet has stuff works dot Com