Table 2 Comparisons of leavers and active workers according to their work related symptoms and lung function tests at each follow up period point.

	2nd survey (first month)		3rd survey (third month)		4th survey (sixth month)		5th survey (first year)
	Leavers	Active workers	Leavers	Active workers	Leavers	Active workers	Leavers	Active workers
WR‐LRTS, n/N	0/16	5/157	6/24	6/125	3/17	17/111	0/17	4/93
(%)	–	(3.2)	(25.0)*	(4.8)	(17.6)	(15.3)	–	(4.3)
WR‐URTS, n/N	4/16	50/157	12/24	49/125	7/17	49/111	4/17	32/93
(%)	(25.0)	(31.8)	(50.0)	(39.2)	(41.2)	(44.1)	(23.5)	(34.4)
Cross shift ΔFEV1	3/16	31/146	2/23	16/123	0/17	10/111	3/17	21/92
−5% ⩽, n/N (%)	(18.8)	(21.2)	(8.7)	(13.0)	–	(9.0)	(17.6)	(22.8)
Cross week ΔFEV1	4/13	47/138	3/19	26/110	1/17	18/111	4/17	21/91
−5% ⩽, n/N (%)	(30.8)	(34.1)	(15.8)	(23.6)	(5.9)	(16.2)	(23.5)	(23.1)

WR‐LRTS, work related lower respiratory tract symptoms; WR‐URTS, work related upper respiratory tract symptoms; Δ, change.

*p<0.005.