The study, which was based on behavioral risk factor data from the federal government, looked at the experience of tobacco users in the first year of Obamacare enrollment, 2014.
"On average, 49-year-old smokers living in one of the 43 states that allowed surcharges in 2014 faced a median tobacco surcharge of $70 per month," the authors wrote.
"Smokers were 7.3 percentage points less likely than nonsmokers to have coverage," the study found.
The study also found that as surcharges increased they had a bigger effect on dampening enrollment among tobacco users.
After Obamacare took effect, smokers facing the higher surcharges had increases in their insurance coverage that was about 12 percentage points lower than smokers who faced no surcharges.
And, "an analysis of the sample younger than age forty showed a 20-percentage-point reduction," the authors wrote.
Smokers facing medium surcharges had increases in their health coverage that was 4.3 percentage points lower than smokers who faced no surcharges.
Yale professor Susan Busch, the study's senior author, said that the larger effects of the higher surcharges seen on younger smokers "are particularly concerning."
Busch noted that because this group "has lower health-care costs than older individuals... their exclusion may reduce the" long-term stability of Obamacare marketplaces "by limiting risk-pooling." Risk-pooling refers to insurance plans combining individuals with low health costs with others with higher health costs, so that the premiums paid by the healthier people offset the benefits paid out to the sicker people.