[填空题]American researchers say they have found that short-term increases in ozone lead to higher death rates in cities.
Ozone is a form of oxygen. The gas is produced naturally in the (26) atmosphere to protect the Earth against (27) from the sun. But human activity can also create ozone in the lower atmosphere.
Gasses from (28) and industry react with sunlight to form this ozone. Levels usually increase in the warmer months. Ozone is the main (29) in smog, the air pollution that is a (30) of fog and smoke.
Ozone has been linked to heart and lung problems especially, and to higher rates of hospital cases. Researchers from Yale University and Johns Hopkins University did the study. Michelle Bell of Yale was the lead (31) . The Journal of the American Medical Association published the results.
The research suggests that even a small increase in ozone, ten parts per thousand million, can lead to higher

[单项选择]American researchers say they have found the strongest connection between ozone(臭氧) pollution and damage to health. Their findings show that short-term increases in ozone lead to higher death rates in cities.
Ozone is form of oxygen. The gas is produced naturally in the upper atmosphere to protect the earth against radiation from the sun. But human activities can also create ozone in the lower atmosphere. Gasses from cars and industry react with sunlight to form this ozone. Levels usually increase in the warmer months. Ozone is the main chemical in smog, the air pollution that is a combination of fog and smoke.
Ozone has been connected with heart and lung problems especially, and with higher rates of hospital cases. Researchers from Yale University and Johns Hopkins University did the study. Michelle Bell of Yale was the lead researcher. The Journal of the American Medical Association published the results. The researchers collected information on 95 American cities. These co
A. death rates are connected with ozone levels
B. ozone is made up of two parts
C. lung cancers are connected with ozone levels
D. the environment goes worse and worse in American