"Age" "n" "Smoking.status" "Breathing.test"
"1" "<40" 577 "Never.smoked" "Normal"
"2" "<40" 27 "Never.smoked" "Borderline"
"3" "<40" 7 "Never.smoked" "Abnormal"
"4" "<40" 192 "Former.smoker" "Normal"
"5" "<40" 20 "Former.smoker" "Borderline"
"6" "<40" 3 "Former.smoker" "Abnormal"
"7" "<40" 682 "Current.smoker" "Normal"
"8" "<40" 46 "Current.smoker" "Borderline"
"9" "<40" 11 "Current.smoker" "Abnormal"
"10" "40-59" 164 "Never.smoked" "Normal"
"11" "40-59" 4 "Never.smoked" "Borderline"
"12" "40-59" 0 "Never.smoked" "Abnormal"
"13" "40-59" 145 "Former.smoker" "Normal"
"14" "40-59" 15 "Former.smoker" "Borderline"
"15" "40-59" 7 "Former.smoker" "Abnormal"
"16" "40-59" 245 "Current.smoker" "Normal"
"17" "40-59" 47 "Current.smoker" "Borderline"
"18" "40-59" 27 "Current.smoker" "Abnormal"