Table 2.

NHANES III respiratory symptoms in tobacco and cannabis users

	Tobacco-only, n (%)	Cannabis and tobacco, n (%)	P-value
Has a doctor ever told you that you have chronic bronchitis?	36 (14.5)	37 (14.7)	0.92
Do you usually cough on most days for 3 consecutive months or more during the year?	74 (29.8)	102 (40.5)	0.024
Do you bring up phlegm on most days for 3 consecutive months or more during the year?	58 (23.4)	97 (38.5)	0.001
Are you troubled by shortness of breath when hurrying on level ground or walking up a slight hill?	110 (44.4)	120 (47.6)	0.63
Have you had wheezing or whistling in your chest at any time during the past 12 months?	126 (50.8)	167 (66.3)	<0.001
Apart from when you have a cold does your chest ever sound wheezy or whistling?	106 (42.7)	146 (57.9)	0.002
During the past 12 months have you had pneumonia?	12 (4.8)	9 (3.6)	0.60