AP Environmental Science (APES) Atmospheric Pollution Practice Test

Emissions control for particulates relies on devices that collect solid particles from the gas. An electrostatic precipitator charges the particles as exhaust flows through, then uses electrically charged plates to attract and trap them on a collection surface. The collected dust is periodically removed, making this method highly effective for a wide range of particle sizes, especially in high-volume, hot gas streams typical of smokestacks. Baghouse filters rely on fabric filter bags to capture particles as gas passes through, which works well but can suffer from pressure drop and clogging. Cyclone separators use centrifugal forces to fling larger particles to the wall for collection, but are less efficient for fine particulates. Scrubbers remove gases (and some particulates) by contacting the gas with a liquid, but they’re primarily for gas pollutants rather than particulate capture alone.