yield ozone   so2      group
1.52  absent  absent   aa
1.85  absent  absent   aa
1.39  absent  absent   aa
1.49  absent  present  ap
1.55  absent  present  ap
1.21  absent  present  ap
1.15  present absent   pa
1.30  present absent   pa
1.57  present absent   pa
0.65  present present  pp
0.76  present present  pp
0.69  present present  pp