VOA慢速英语:美国野火烟雾给数百万人带来健康问题

expose - v. to leave (something) without covering or protection

concentration - n. the amount of a component in a given area or volume

remote - adj. far away

asthmatic - adj. relating to asthma, a lung disorder that causes periods of wheezing, coughing, and difficulty with breathing

button - n. a small part of a machine that you push to make the machine work

function - n. the special purpose or activity for which a thing exists or is used

source - n. the cause of something; someone or something that provides what is wanted or needed

ton - n. a measure of weight equal either to 2000 pounds (about 907 kilograms) (short ton) or 2240 pounds (about 1016 kilograms; long ton ) with the short ton being more frequently used in the United States and Canada

irritate - v. to make (someone) impatient, angry, or annoyed

symptom - n. a change in the body or mind which indicates that a disease is present