My research (here) has explored why the NHIS and NSDUH estimates are so divergent.
FORBES: Are Federal Taxes Driving Smokers to Stop Lighting Up?
2.
They use the lower NHIS numbers to boast about declining smoking rates, which they attribute to higher taxes and smoking bans.
FORBES: Are Federal Taxes Driving Smokers to Stop Lighting Up?
3.
The Office on Smoking and Health at the Centers for Disease Control and Prevention (CDC) counted 45.3 million American smokers, using the NHIS (available here).
FORBES: Are Federal Taxes Driving Smokers to Stop Lighting Up?