Particle pollution — also called particulate matter (PM) — is made (1) …………… of particles of solids or liquids that are in the air. Particle pollution can come from two different kinds of (2) …………… — primary or secondary. Primary sources cause particle pollution on their own. For example, wood stoves and forest fires are primary sources. Secondary sources let (3) …………… gases that can form particles. Power plants and coal fires are examples of secondary sources. Some other common sources of particle pollution can be either (4) ………….. or secondary — for example, factories, cars and trucks, and construction sites. Smoke from fires and emissions from power plants, industrial facilities, and cars and trucks contain PM2.5. Breathing in particle pollution can be (5) …………… to your health. Coarse particles, called PM10, can irritate your eyes, nose, and throat. Dust from roads, farms, dry riverbeds, construction (6) ……………, and mines are types of PM10. Fine particles, called PM2.5, are more (7) …………… because they can get into the deep parts of your lungs — or even into your blood.

1. (a) out (b) up (c) along (d) over
2. (a) limit (b) news (c) contact  (d) sources
3. (a) out (b) down (c) off (d) in
4. (a) irritation (b) asthma (c) primary (d) anyone
5. (a) harmful (b) truth (c) existence (d) invent
6. (a) sites (b) persist (c) outdoor (d) controlling
7. (a) include (b) dangerous (c) releases (d) inevitable

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