VOA慢速英语:Polish Engineers Make Air-Cleaning Device

premature – adj. happening, arriving, existing, or performed before the proper, usual, or intended time

particulate matter – n. the term for a mixture of solid particles and liquid droplets found in the air (also called particle pollution.) Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.

naked eye – n. the eye unaided by any instrument that changes the apparent size or distance of an object or otherwise alters visual powers

ionized – v. to convert wholly or partly into ions

automatic – adj. having controls that allow something to work or happen without being directly controlled by a person

exhaust – n. the mixture of gases produced by an engine

chimney – n. a part of a building through which smoke rises into the outside air

deposit – v. to put or leave (someone or something) in a particular place

infrastructure – n. the basic equipment and structures (such as roads and bridges) that are needed for a country, region, or organization to function properly

emission – n. substances discharged into the air (as by a smokestack or an automobile engine

transition – v. passage from one state, stage, subject, or place to another