But that has changed drastically. In the survey period 2017-18, the current and previous smoking rates among the richest fell by almost half to 34 percent – while the rates among the poorest rose to 57.9 percent.

Although smoking is an acquired habit, lower-income people may be more likely to use tobacco to cope with the stress of poverty, said Dr. Gaffney. Tobacco advertising is often aimed at low-income communities, and according to the authors of a comment accompanying the study, there are higher densities of tobacco shops in poor areas. Poor people may also have more limited access to smoking cessation programs and replacement therapies, they said.

“We are increasingly thinking of tobacco addiction as a disease,” said Dr. Sarath Raju, Assistant Professor of Pulmonary and Intensive Care Medicine at Johns Hopkins University and one of the authors of the comment. “Individual responsibility is important, but without proper treatment or access to treatment to help you quit, this is a challenge.”

The asthma rate in children rose in all income groups after 1980, but more so in children from poorer households. Asthma rates in young children 6-11 years old prior to 1980 differed little between 3 and 4 percent. In 2017-18, the rates among the poor rose to 14.8 percent, compared with 6.8 percent for children from families with the highest incomes. (A similar pattern was seen in adults; statistical adjustments for smoking reduced the differences only slightly.)

Low-income adults have long had higher rates of chronic obstructive pulmonary disease, an inflammatory lung disease, than wealthier people. But rates have increased and the gap has widened. The prevalence among the poorest Americans rose from 10.4 percent to 16.3 percent, although the rate among the richest remained stable at 4.4 percent.

Between 1959 and 2019, poorer and less educated adults consistently reported more worrisome breathing conditions, such as shortness of breath, than wealthier, educated people. For some symptoms, such as For example, if you had a problem with coughing, the gap between rich and poor widened over time.

Wheezing rates fell for the highest-income and best-educated groups, but remained stable in the poor, least-educated groups, the study found.