In the paper they claim it matters for midlife mortality too:
> People who start smoking at age 18 begin to exhibit higher mortality several decades later, with particularly large effects beginning at ages 45–64 (Lawton et al. 2025). A health-capital model allows the mortality rates of older persons to be determined not only by their current smoking behavior but also by smoking in earlier years. In the United States, smoking rates started falling for college graduates earlier than they did for the non-college population.
...
> [...] with rapidly improving treatments and screening for lung cancer (Howladeret al. 2020), the major impact of smoking over the longer-term—particularly for people aged 55–64 arises from other more-common tobacco-related diseases such as chronic obstructive pulmonary disease (COPD); cardiovascular diseases such as strokes, aneurysms, and heart
attacks; diabetes; and other types of cancers (Carter et al. 2015). Perhaps more surprising is that past county-level smoking rates are highly predictive of deaths of despair. This finding, however, is consistent with an emerging literature in biology that points to a causal influence
of smoking on drug addiction [...]
