What effect are smoke-free laws having on your blood pressure?

In the first study of its kind, researchers draw conclusions on the effects of smoke-free laws on blood pressure.7131

In the first study to examine the effect of smoke-free policies on blood pressure, a team of researchers has shown that non-smokers with access to smoke-free restaurants, bars and workplaces have a lower blood pressure than those who lived in areas without smoke-free policies.

An association had previously been made linking reduced rates of hospitalization for heart disease with these smoke-free laws; however, there had been no previous study into the effect on blood pressure.

In this study – termed CARDIA – 5115 adults aged 18–30 from four different US cities were enrolled in 1985. Follow-up exams were conducted up to 30 years later, with researchers analyzing data from 1995–2011 to align with the timing of the introduction of smoke-free policies. Participants were excluded who hadn’t had at least two blood pressure readings in that time.

A total of 2606 participants were used for the final study. By 2011, participants who lived in smoke-free areas had systolic blood pressure levels on average 1.14–1.52 mm Hg lower than those in areas without such laws.

“Smoke-free laws were associated with reduced systolic blood pressure, but surprisingly not with reductions in diastolic blood pressure or high blood pressure. It’s not entirely certain why this was the case, but it’s possible that we are detecting effects on systolic blood pressure that are below the threshold for hypertension,” explained lead author Stephanie Mayne (Northwestern University; IL, USA).

Even when systolic blood pressure levels are below the threshold for hypertension, a higher systolic blood pressure still increases the risk of cardiovascular disease. Therefore, the reductions in systolic blood pressure seen in this study could still suggest a potentially significant effect on population-level risk.

“Also, when we looked at differences in blood pressure over time within individuals, comparing years when they lived in an area with a smoke-free law to years when they didn’t, systolic blood pressure was lower on average when they lived in an area with smoke-free laws, after accounting for overall trends in blood pressure and for how people’s levels of risk factors like diet and physical activity changed over the study period,” commented Mayne.

The researchers believe this may point to an improvement in population level heart health, despite changes at an individual level being small.