Author Question: More than ____percent of the total PM2.5 particles emissions across the United States in recent ... (Read 105 times)

nramada · **on:** Jul 13, 2018

More than ____percent of the total PM2.5 particles emissions across the United States in recent years have been attributed to emissions from wildland fires.
a. 2
b. 5
c. 10
d. 25
e. 50

Question 2

Suspended particles from sources in Europe and the former Soviet Union are believed responsible for the brownish cloud layer called ____ that forms over the Arctic each spring.
a. the ozone hole
b. Asian dust
c. Arctic haze
d. acid rain
e. acid fog