Table 2

Kendall's correlation coefficients among different environmental variables and asthenopia

Variables	1	2	3	4	5	6	7
1 Noise	—
2 Crowding	0.23^2-150
3 Lighting	0.00	0.33^2-160
4 Smoke	0.24^2-160	0.03	0.50^2-160
5 Stale air	0.23^2-160	0.27^2-160	0.33^2-160	0.28^2-160
6 Temperature	0.00	0.02	0.05	0.00	0.08
7 Dampness	0.06	0.09	0.12	0.01	0.03	0.08
8 Asthenopia	0.27^2-160	0.012	0.09	0.28^2-160	0.14	0.06	0.11

↵2-150 p<0.05;
↵2-160 p<0.01 two tailed.