Catalytic converters are increasingly being fitted to cars as a means of reducing some of the harmful emissions from car exhausts.
But, though they eliminate one form of pollution, their action serves only to create another one.
Ground-level ozone is kept at very low levels in cities by some of the pollutants catalysts remove.
So the more catalytic converters that are fitted, the more such ozone can build up.
Since ozone is a major cause of choking summer smogs, we can assume that people with breathing difficulties, such as asthmatics, will be much worse off the more that catalytic converters are used.
We should stop fitting cars with catalytic converters.
Which of the following, if true, would most weaken the above argument?
