WEBVTT - What's the Most Dangerous Air Pollution?

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<v Speaker 1>Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff,

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<v Speaker 1>Lauren Vogel bomb here. When we think of air pollution,

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<v Speaker 1>we usually think of black clouds pouring out of smoke

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<v Speaker 1>stacks or the unsightly brown haze that hangs over many

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<v Speaker 1>of the world's cities. But in recent years, scientists have

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<v Speaker 1>found increasing evidence of health risks from a part of

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<v Speaker 1>air pollution that we don't see and that isn't yet

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<v Speaker 1>regulated under federal air quality standards. In addition to visible emissions,

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<v Speaker 1>the burning of fossil fuels and other types of combustions

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<v Speaker 1>create vast quantities of ultrafying particles somewhere around a thousand

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<v Speaker 1>of the width of a human hair, that we inhale

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<v Speaker 1>without ever realizing it. We spoke with Bart Astro, former

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<v Speaker 1>chief of Air Pollution Epidemiology for the California Environmental Protection

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<v Speaker 1>Agency and currently a researcher at University of California Davis.

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<v Speaker 1>He said that ultrafined particles come from an array of sources.

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<v Speaker 1>They're emitted from vehicles, especially ones that burned diesel fuel,

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<v Speaker 1>as well as smaller g selene burning engines such as

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<v Speaker 1>the ones in lawnmowers and leafblowers, but other types of

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<v Speaker 1>burning wood, fires, burning leaves, and secondhand smoke from cigarettes,

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<v Speaker 1>for example, also produce ultrafine particles. So does cooking meat

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<v Speaker 1>on the stove in your kitchen. Nevertheless, it's a challenge

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<v Speaker 1>to figure out the extent of our exposure to ultrafine particles.

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<v Speaker 1>Because the particles are so small and so transient, they

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<v Speaker 1>quickly disperse or else coagulate into bigger particles. They're a

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<v Speaker 1>type of air pollution that is especially difficult to measure.

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<v Speaker 1>Astro said. Ultrafine particles are very high in concentration next

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<v Speaker 1>to roadways, for example, but if you go three hundred

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<v Speaker 1>to five hundred yards away, that's about two hundred and

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<v Speaker 1>fifty to four fifty the ultrafines go down to almost

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<v Speaker 1>background levels. In recent years, scientists at University of California,

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<v Speaker 1>Davis have developed sophisticated modeling methods that combine sensing data

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<v Speaker 1>with knowledge about how chemical processes and meteorological conditions affect

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<v Speaker 1>these particles. That's allowed them to predict concentrations over several years,

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<v Speaker 1>which in turn makes it easier to study the particles

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<v Speaker 1>effects on human health. Austro was the lead author on

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<v Speaker 1>a study published in twenty fifteen The combined such modeling

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<v Speaker 1>with health data on one hundred thousand middle aged female

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<v Speaker 1>teachers and administrators that were recruited from the State Teachers

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<v Speaker 1>Retirement System. It found an association between ultrafined particles and

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<v Speaker 1>death from heart disease Since then. Seventeen study also found

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<v Speaker 1>that long term exposure to ultrafine particles around highways was

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<v Speaker 1>associated with cardiovascular diseases and hypertension, and eighteen study in

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<v Speaker 1>the journal Environmental Pollution suggests that simply moving a bus

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<v Speaker 1>stop forty to fifty away from an intersection that's about

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<v Speaker 1>a hundred and thirty and fifty feet can substantially reduce

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<v Speaker 1>transit users exposure to high levels of ultrafined particles. It

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<v Speaker 1>may seem strange that something so small could be so dangerous,

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<v Speaker 1>but because of their size, ultrafine particles have an easier

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<v Speaker 1>time getting into lung tissue and causing inflammation. Research has

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<v Speaker 1>found that even a brief amount of ultrafine particle exposure

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<v Speaker 1>can increase the allergic inflammation that makes asthma worse. But

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<v Speaker 1>that's not the only worry. Ultrafine particles are so tiny

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<v Speaker 1>that they can penetrate the blood brain barrier and be

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<v Speaker 1>absorbed in into brain tissue. Recent research suggests a possible

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<v Speaker 1>link between the tiny particles and Alzheimer's disease and other

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<v Speaker 1>forms of dementia. Scientists also have found that mice exposed

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<v Speaker 1>to ultrafine particles early in life had changes in their

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<v Speaker 1>brains that bore resemblance to those set in humans with

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<v Speaker 1>autism and schizophrenia. Despite all that, federal air pollution standards

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<v Speaker 1>don't yet set limits for ultrafined particles due to the

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<v Speaker 1>developing state of the scientific evidence about their health effects

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<v Speaker 1>and the current limitations on monitoring technology, but Ostro says

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<v Speaker 1>there are some measures that people can take to protect

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<v Speaker 1>themselves from ultrafine particles. If you have pre existing conditions

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<v Speaker 1>such as cardiovascular or respiratory diseases, it's a good idea,

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<v Speaker 1>for example, to limit your exposure to emissions such as

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<v Speaker 1>diesel fumes, car exhaust, and any sort of burning biomass.

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<v Speaker 1>And even if you're healthy, you'll probably want to avoid

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<v Speaker 1>such exposure as well, which means shifting your running routes

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<v Speaker 1>away from major roadways is a really good idea. Today's

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<v Speaker 1>episode was written by Patrick Jake Tiger and produced by

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<v Speaker 1>Tristan McNeil. And Tyler Clang. For more on this and

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<v Speaker 1>other topics. To help you breathe a little easier, visit

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<v Speaker 1>our home planet has stuff works dot Com