Table 5.

Correlation of FeNO with observed smoking variables and eCO ppm

Parameters	FeNO (ppb)
	R value	P value
Smoking duration (years)	−0.138	<0.001*
No of cigarettes/days	−0.132	0.014†
Brinkman Index	−0.243	<0.001*
eCO ppm	−0.281	<0.001*

(Spearman correlation)

*p<0.001.

†*p<0.05.

eCO, exhaled breath carbon monoxide; FeNO, fractional exhaled nitric oxide.