n | 425 | 419 | |

Using inhaled steroids (n (%)) | 29% of 373* | 43% of 386* | 0.001 |

FEV_{1} % predicted (mean (SD (median))) | 97.6 (21.8 (99.35)) | 93.2 (25.3 (94.35)) | 0.01 |

VC % (mean (SD (median))) | 102.5 (18 (103.5)) | 99.3 (19.4 (99.9)) | 0.02 |

FEF_{50} % (mean (SD (median))) | 84.3 (36 (84.8)) | 75.8 (37.8 (74.7)) | 0.01 |

FEF_{25} % (mean (SD (median))) | 73.3 (46 (63.1)) | 70.1 (44 (59.6)) | NS |

Actual FEV_{1}/VC (mean (SD (median))) | 75.6 (10.8 (77.45)) | 73.6 (13.6 (75.29)) | 0.03 |

Methacholine PC_{20} during work period (mean (SD (median))) | 4.6 (11.5 (0.9)) (n=101) | 2.8 (6.7 (1.1)) (n=107) | NS |

Methacholine PC_{20} off work (mean (SD (median))) | 18.4 (23.5 (7.7)) (n=239)* | 17.4 (24.1 (4.3)) (n=199)* | NS |

At least one hospital admission for asthma up to 1996 (n (%)) | 5.3% of 414* | 11.1% of 396* | 0.003 |