Table 4 Regression analysis between respiratory symptoms/illnesses adjusted with age, duration of work and smoking

  Exposed

2.30 (1.13–4.67)^a

2.35 (1.14–4.85)^a

  Referent

Reference

Reference

  Exposed

3.22 (1.20–8.66)^a

2.98 (1.07–8.24)^a

  Referent

Reference

Reference

  Exposed

1.95 (1.30–2.91)^b

1.91 (1.26–2.90)^b

  Referent

Reference

Reference

  Exposed

6.21 (2.89–13.36)^c

6.00 (2.78–12.94)^c

  Referent

Reference

Reference

  Exposed

3.74 (1.60–8.76)^b

3.18 (1.34–7.58)^b

  Referent

Reference

Reference

  Green brick molding

5.80 (1.20–27.93)^a

4.46 (0.84–23.75)

  Green brick stacking/carrying

3.03 (0.60–15.40)

5.61 (0.99–31.78)

  Red brick loading/carrying

2.44 (0.45–12.76)

4.13 0.71–24.09)

  Firing

4.39 (0.89–21.61)

2.24 (0.41–12.17)

  Coal crushing/carrying

Reference

Reference

  Green brick molding

7.94 (1.54–41.10)^a

2.79 (0.43–18.17)

  Green brick stacking/carrying

2.81 (0.53–15.03)

4.43 (0.72–27.39)

  Red brick loading/carrying

3.01 (0.60–16.02)

3.95 (0.66–23.62)

  Firing

2.14 (0.36–12.63)

0.66 (0.09–5.13)

  Coal crushing/carrying

Reference

Reference

  Green brick molding

1.15 (0.46–2.84)

1.15 (0.44–2.99)

  Green brick stacking/carrying

0.72 (0.27–1.94)

0.94 (0.33–2.68)

  Red brick loading/carrying

2.45 (1.10–5.57)^a

3.08 (1.26–7.51)^a

  Firing

2.58 (1.13–5.87)^a

2.03 (0.84–4.87)

  Coal crushing/carrying

Reference

Reference

  Green brick molding

1.55 (0.57–4.23)

1.35 (0.48–3.82)

  Green brick stacking/carrying

0.93 (0.31–2.80)

0.90 (0.29–2.81)

  Red brick loading/carrying

2.29 (0.88–5.91)

2.12 (0.79–5.67)

  Firing

0.51 (0.14–1.80)

0.39 0.11–1.47)

  Coal crushing/carrying

Reference

Reference

  Green brick molding

1.95 (0.47–8.10)

1.75 (0.40–7.63)

  Green brick stacking/carrying

1.95 (0.47–8.10)

1.95 (0.45–8.52)

  Red brick loading/carrying

3.24 (0.87–12.30)

3.06 (0.77–12.08)

  Firing

0

0

  Coal crushing/carrying

Reference

Reference