Table 3. Univariable meta-regression model.

Variables	Coefficient	P-value	95% CI
Type of factory
Cement	0.08	0.843	-0.555–1.216
Flour mill	0.33	0.464	-0795-0.938
Textile	0.07	0.872	-0.964–0767
Wood	0.36	0.425	-0.530–1.259
Paper	Reference
Constant	0.08	0.843	-0.693–0.848
Study settings (region)
Addis Ababa	-0.16	0.698	-0.959–0.642
Amhara	-0.29	0.473	-1.085–0.503
Oromia	-027	0.544	1.138–0.600
SNNPR	Reference
Constant	0.41	0.236	-0.271–1.099
Sample size
<262	Reference
≥262	0.05	0.832	-0.419–0.520
Constant	0.18	0.322	-0.175–0.532