Smokers in poorer neighborhoods lost lung function faster and died sooner

Lungs age like the rest of the body. From early adulthood on, the amount of air a person can blow out falls a little every year, and anything that speeds up that slide — above all smoking — raises the risk of chronic lung disease, lung cancer and early death. Doctors call a faster-than-usual slide "accelerated lung aging".

Where a person lives may also play a part. People in poorer neighborhoods smoke more on average, breathe dirtier air, live in worse housing and have less access to good medical care. Earlier work had linked neighborhood disadvantage to more lung disease and more deaths from it, but few studies had followed the lungs of the same people over many years to see whether they actually declined faster. A new analysis of a long-running group of smokers in New Mexico did that.

What they did

The researchers used the Lovelace Smokers Cohort, which since 2001 has enrolled current and former smokers aged 40 to 75 in and around Albuquerque. Everyone had smoked at least 10 pack-years (for example, a pack a day for ten years). After exclusions for missing data, 2,362 people were analyzed: average age 56, about three in four of them women.

Roughly every 18 months, participants took a breathing test called spirometry. Two numbers matter here. FEV1 is how much air someone can force out in the first second of a hard breath out; it falls when airways narrow. FVC is the total amount they can blow out. The ratio of the two drops when air gets trapped, as happens in smoking-related lung disease. Participants also filled in questionnaires on how their breathing affected daily life, and deaths were traced through a national death register until October 2020.

Each person's home census tract — a small area of a few thousand residents — was scored with two standard measures. The Social Deprivation Index combines 7 mostly economic indicators, such as income and education. The Social Vulnerability Index combines 15, including housing, transport, disability and language. Higher scores mean a more disadvantaged area. The results are given per step from a fairly advantaged to a fairly disadvantaged area within this group (the gap between the 25th and 75th percentiles).

What they found

• Weaker lungs at the start. Per step up in deprivation, people's FEV1 was about 0.09 litres lower, and their FEV1/FVC ratio about 1.2 percentage points lower.
• A faster yearly decline. Per step up in social vulnerability, FEV1 fell by an extra 3.1 millilitres a year. Total lung volume (FVC) did not fall faster.
• Worse daily life. People in more vulnerable areas reported more breathing problems; the difference in the questionnaire's total score (about 4.5 points) passed the 4-point threshold usually taken as noticeable to patients.
• Higher risk of death. Per step up, the risk of death from all causes during follow-up was roughly a quarter higher with either index (hazard ratios 1.28 and 1.27). Cancer deaths were not linked to neighborhood.

The team also asked which personal factors might carry these links. Still smoking was the biggest one: depending on the outcome, it accounted for between about 4% and 31% of the association. Diet quality and education accounted for smaller shares. For the link with death, people's lung function and breathing-related quality of life at the start accounted for up to about a third.

What to keep in mind

The authors point out that everyone in the study was a current or former smoker, so whether the same links hold for people who never smoked is unknown. Neighborhood was mostly taken from the address at enrollment; the team could not measure how long people had lived there or where they grew up, and people within one census tract can live very different lives. The two indices are broad composites, so they cannot say which feature of a neighborhood — income, housing, transport — matters. The analyses of subgroups and of possible pathways were exploratory.

As with any observational study, the results show links, not causes. Smoking itself accounted for part of the association, and other differences between people in richer and poorer areas could explain more. The yearly difference in decline is also small for any one person; it matters mainly because it adds up over years.

Why it matters

Studies of aging usually look at individual habits and biology. This one adds place: in a group of smokers already at risk, a disadvantaged home area was linked to lungs that started weaker, declined a little faster, felt worse and went with a shorter life. Because part of the association ran through smoking and diet, the researchers suggest that public-health help aimed at disadvantaged neighborhoods — together with attention to the wider social conditions there — could be one way to narrow the gap in lung health. Whether such efforts actually change lung aging would need to be tested directly.