People who live and work in areas with elevated levels of ozone and other airborne pollutants aPPear to run an increased risk of lung cancer，US researchers report in the December issue of the iournal Environmental Health Perspectives．
The researchers，Dr．W．Lawrence Beeson of Loma Linda University in Californja，and colleagues studied more than 4，000 female and 2，000 male，white，nonsmoking volunteers from 1977 t0 1992．
At the start of the study，the volunteers filled out questionnaires about their occupations，their exercise patterns，diet and other lifestyle choices，and their family’s health history．The questionnaires also asked whether the volunteers had any respiratory symptoms，how many hours they spent outdoors， and where they lived and worked．The researchers updated this information in 1987 and again in 1992．
Using air quality monitoring station data，Beeson and colleagues then determined the levels of particle soot，ozone or“smog"，sulfur dioxide，and other pollutants that the volunteers were exposed to。 given where they lived and worked．Over the course of the 15一year study，20 0f the women and 16 0f the men in the study were diagnosed with lung cancer．
Analyzing the relationship between exposure to airborne pollutants and lung cancer risk，the researchers found that both men and women regularly exposed to levels of particle soot that were lower than the National Ambient Air Quality Standard of 50 micrograms per meter cubed ran an increased risk of lung cancer．①And both men and women exposed to elevated levels of sulfur dioxide ran an increased risk of lung cancer．
In addition，men regularly exposed to ozone levels of 80 parts per billion(ppb)ran more than three times the risk of lung cancer as men exposed to lower levels．The Environmental Protection Agency(EPA)limit on ozone is 120 ppb，Beeson and colleagues report．Women，however，did not appear to run an increased risk of lung cancer if exposed to high levels of sm09．
“This gender difference may he due to the males spending much more time outdoors than females．” they write． “This was especially true for the summer when ozone levels are higher．The difference mav also have been due to hormonal differences，they add．Some research findings also suggest that the female sex hormone estrogen may partly offset the consequences of exposure to high ozone levels．
“Our findings suggest that the current EPA standard of l20 ppb for ozone may not adequatelv protect the large portion of the US male population who live or work in communities where the current standard for ozone is frequently exceeded，”Beeson and colleagues conclude．“More research with a larger number of incident cases of lung cancer is needed to better understand the observed gender difference in regard to ozone exposure as well as to better separate the independent effects of ozone。airborne particulate matter，sulfur dioxide，”and other airborne pollutants．[476 words]
1．In the research done by Dr．Beeson and his colleagues，______．
A．researchers asked the volunteers to fill out questionnaires once a year
B．researchers intentionally studied twice as many female as male volunteers
C．the volunteers were asked to expose to high levels of airborne pollutants
D．the volunteers were asked to fill out questionnaires three times in l5 years
2．It was found in the research that did not seem to run an increased risk of lung cancer ______．
A．women exposed to high levels of sulfur dioxide
B．men regularly exposed tO high levels of sulfur dioxide
C．women exposed to high levels of smog
D．men regularly exposed to high levets of smog
3．Which of the following statements is TRUE?
A．Females are much stronger than males in many aspects
B．Males are more vulnerable to dangers in life than females．
C．Spending much time outdoors in summer is not harmful to females．
D．Male sex hormone may not be able to decrease the effect of exposure to high ozone levels．
4．It seems that ______．
A．more male volunteers should be used in the research
B．the current EPA standard should be modified
C．ozone exposure leads to the highest risk of lung cancer
D．there is no way to escape the risk of lung cancer
5．The proper title for this passage should be ______．
A．Smog Appears to Up Lung Cancer Risk
B．Airborne Pollutants
C．Lung Cancer Risk
D．The Gender Difference
The researchers，Dr．W．Lawrence Beeson of Loma Linda University in Californja，and colleagues studied more than 4，000 female and 2，000 male，white，nonsmoking volunteers from 1977 t0 1992．
At the start of the study，the volunteers filled out questionnaires about their occupations，their exercise patterns，diet and other lifestyle choices，and their family’s health history．The questionnaires also asked whether the volunteers had any respiratory symptoms，how many hours they spent outdoors， and where they lived and worked．The researchers updated this information in 1987 and again in 1992．
Using air quality monitoring station data，Beeson and colleagues then determined the levels of particle soot，ozone or“smog"，sulfur dioxide，and other pollutants that the volunteers were exposed to。 given where they lived and worked．Over the course of the 15一year study，20 0f the women and 16 0f the men in the study were diagnosed with lung cancer．
Analyzing the relationship between exposure to airborne pollutants and lung cancer risk，the researchers found that both men and women regularly exposed to levels of particle soot that were lower than the National Ambient Air Quality Standard of 50 micrograms per meter cubed ran an increased risk of lung cancer．①And both men and women exposed to elevated levels of sulfur dioxide ran an increased risk of lung cancer．
In addition，men regularly exposed to ozone levels of 80 parts per billion(ppb)ran more than three times the risk of lung cancer as men exposed to lower levels．The Environmental Protection Agency(EPA)limit on ozone is 120 ppb，Beeson and colleagues report．Women，however，did not appear to run an increased risk of lung cancer if exposed to high levels of sm09．
“This gender difference may he due to the males spending much more time outdoors than females．” they write． “This was especially true for the summer when ozone levels are higher．The difference mav also have been due to hormonal differences，they add．Some research findings also suggest that the female sex hormone estrogen may partly offset the consequences of exposure to high ozone levels．
“Our findings suggest that the current EPA standard of l20 ppb for ozone may not adequatelv protect the large portion of the US male population who live or work in communities where the current standard for ozone is frequently exceeded，”Beeson and colleagues conclude．“More research with a larger number of incident cases of lung cancer is needed to better understand the observed gender difference in regard to ozone exposure as well as to better separate the independent effects of ozone。airborne particulate matter，sulfur dioxide，”and other airborne pollutants．[476 words]
1．In the research done by Dr．Beeson and his colleagues，______．
A．researchers asked the volunteers to fill out questionnaires once a year
B．researchers intentionally studied twice as many female as male volunteers
C．the volunteers were asked to expose to high levels of airborne pollutants
D．the volunteers were asked to fill out questionnaires three times in l5 years
2．It was found in the research that did not seem to run an increased risk of lung cancer ______．
A．women exposed to high levels of sulfur dioxide
B．men regularly exposed tO high levels of sulfur dioxide
C．women exposed to high levels of smog
D．men regularly exposed to high levets of smog
3．Which of the following statements is TRUE?
A．Females are much stronger than males in many aspects
B．Males are more vulnerable to dangers in life than females．
C．Spending much time outdoors in summer is not harmful to females．
D．Male sex hormone may not be able to decrease the effect of exposure to high ozone levels．
4．It seems that ______．
A．more male volunteers should be used in the research
B．the current EPA standard should be modified
C．ozone exposure leads to the highest risk of lung cancer
D．there is no way to escape the risk of lung cancer
5．The proper title for this passage should be ______．
A．Smog Appears to Up Lung Cancer Risk
B．Airborne Pollutants
C．Lung Cancer Risk
D．The Gender Difference