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Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hi

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Speaker 1: brain Stuff Lauren bog Bomb here with a classic episode

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Speaker 1: from our archives. One of the many reasons we have

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Speaker 1: to reduce pollution is the negative health effects that may

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Speaker 1: have on us. Today, we look at how the tiniest

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Speaker 1: particles of air pollution can actually be the most dangerous.

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Speaker 1: Hey brain stuff, Lauren vogle Bomb here. When we think

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Speaker 1: of air pollution, we usually think of black clouds pouring

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Speaker 1: out of smoke stacks, or the unsightly brown haze that

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Speaker 1: hangs over many of the world's cities. But in recent years,

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Speaker 1: scientists have found increasing evidence of health risks from a

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Speaker 1: part of air pollution that we don't see and that

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Speaker 1: isn't yet regulated under federal air quality standards. In addition

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Speaker 1: to visible emissions, the burning of fossil fuels and other

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Speaker 1: types of combustions create vast quantities of ultrafying particles somewhere

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Speaker 1: around a thousand of the width of a human hair,

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Speaker 1: that we inhale without ever realizing it. We spoke with

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Speaker 1: Bart Astro, former chief of Air Pollution Epidemiology for the

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Speaker 1: California Environmental Protection Agency and currently a researcher at University

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Speaker 1: of California Davis. He said that ultrafined particles come from

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Speaker 1: an array of sources. They're emitted from vehicles, especially ones

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Speaker 1: that burned diesel fuel, as well as smaller gasoline burning

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Speaker 1: engines such as the ones in lawnmowers and leaf blowers.

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Speaker 1: But other types of burning wood fires, burning leaves, and

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Speaker 1: secondhand smoke from cigarettes, for example, also produce ultrafined particles,

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Speaker 1: so it does cooking meat on the stove in your kitchen. Nevertheless,

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Speaker 1: it's a challenge to figure out the extent of our

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Speaker 1: exposure to ultrafine particles. Because the particles are so small

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Speaker 1: and so transient, they quickly disperse or else coagulate into

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Speaker 1: bigger particles. They're a type of air pollution that is

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Speaker 1: especially difficult to measure. Astro said. Ultrafine particles are very

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Speaker 1: high in concentration next to roadways, for example, but if

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Speaker 1: you go three hundred to five hundred yards away that's

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Speaker 1: about two hundred and fifty to four hundred and fifty

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Speaker 1: the ultrafines go down to almost background levels. In recent years,

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Speaker 1: scientists at University of California Davis have developed sophisticated modeling

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Speaker 1: methods that combine sensing data with knowledge about how chemical

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Speaker 1: processes and meteorological conditions affect these particles. That's allowed them

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Speaker 1: to predict concentrations over several years, which in turn makes

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Speaker 1: it easier to study the particles effects on human health.

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Speaker 1: Austro was the lead author on a study published in

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Speaker 1: twenty fifteen. The combined such modeling with health data on

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Speaker 1: one hundred thousand middle aged female teachers and administrators that

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Speaker 1: were recruited from the state Teachers Retirement system. It found

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Speaker 1: an association between ultrafine particles and death from heart disease.

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Speaker 1: Since then, a seven team study also found that long

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Speaker 1: term exposure to ultrafine particles around highways was associated with

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Speaker 1: cardiovascular diseases and hypertension, and eighteen study in the journal

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Speaker 1: Environmental Pollution suggests that simply moving a bus stop forty

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Speaker 1: to fifty away from an intersection that's about a hundred

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Speaker 1: and thirty to fifty feet can substantially reduce transit users

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Speaker 1: exposure to high levels of ultrafined particles. It may seem

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Speaker 1: strange that something so small could be so dangerous, but

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Speaker 1: because of their size, ultrafined particles have an easier time

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Speaker 1: getting into lung tissue and causing inflammation. Research has found

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Speaker 1: that even a brief amount of ultrafined particle exposure can

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Speaker 1: increase the allergic inflammation that makes asthma worse. But that's

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Speaker 1: not the only worry. Ultrafined particles are so tiny that

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Speaker 1: they can penetrate the blood brain barrier and be absorbed

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Speaker 1: in into brain tissue. Recent research suggests a possible link

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Speaker 1: between the tiny particles and Alzheimer's disease and other forms

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Speaker 1: of dementia. Scientists also have found that mice exposed to

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Speaker 1: ultrafine particles early in life had changes in their brains

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Speaker 1: that bore resemblance to those set in humans with autism

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Speaker 1: and schizophrenia. Despite all that, federal air pollution standards don't

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Speaker 1: yet set limits for ultrafined particles due to the developing

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Speaker 1: state of the scientific evidence about their health effects and

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Speaker 1: the current limitations on monitoring technology. But Ostro says there

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Speaker 1: are some measures that people can take to protect themselves

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Speaker 1: from ultrafine particles. If you have pre existing conditions, such

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Speaker 1: as cardiovascular or respiratory diseases, it's a good idea, for example,

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Speaker 1: to limit your exposure to emissions such as diesel fumes,

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Speaker 1: car exhaust, and any sort of burning biomass, and even

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Speaker 1: if you're healthy, you'll probably want to avoid such exposure

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Speaker 1: as well, which means shifting your running roots away from

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Speaker 1: major roadways is a really good idea. Today's episode was

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Speaker 1: originally produced by Tristan Neil and it's based on the

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Speaker 1: article When it comes to air pollution, the Chinese particles

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Speaker 1: might be the worst on how stuff works dot Com,

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Speaker 1: written by Patrick J. Keaiger. Brain Stuff is production of

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Speaker 1: I heart Radio in partnership with how stuff works dot Com,

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Speaker 1: and it's produced by Tyler Klein. For more podcasts my

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Speaker 1: heart Radio, visit the I heart Radio app, Apple Podcasts,

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Speaker 1: or wherever you listen to your favorite shows