Long-term temperature exposure and adult blood pressure in the Northern Finland Birth Cohort 1966

Abstract

Background: Global warming and increased temperature variability due to climate change are associated with cardiovascular health, yet their long-term impact on blood pressure remains unclear. This thesis aimed to examine whether annual average apparent temperature (ApT) and its variability influence adult systolic (SBP) and diastolic blood pressure (DBP) in the Northern Finland Birth Cohort 1966.

Methods: In this cross-sectional study, 5,389 cohort participants (aged 46 years) attended clinical examinations in 2012-2014. Daily ERA5-Land data were linked to residential addresses to compute yearly ApT and its standard deviation (sdApT) for the 365 days preceding measurement. Generalized additive models were used to test non-linearity, and multivariable linear regression was applied to evaluate the associations, adjusting for demographic, behavioural, and metabolic factors. Effect modification by urbanicity, obesity, sex, hypertension, and diabetes was explored.

Results: Each 1 °C increase in ApT corresponded to −0.45 mmHg (95 % CI −0.68, −0.22) lower SBP and −0.36 mmHg (−0.52, −0.21) lower DBP. SdApT showed no relation with SBP but was linked to 0.42 mmHg (0.07, 0.78) higher DBP per 1 °C increase. Associations were stronger in urban residents; the ApT–BP link intensified in participants with diabetes, while the sdApT–DBP link appeared only in non-obese individuals. Findings were robust to alternative temperature metrics, complete-case analysis, and exclusion of influential observations.

Conclusions: Warmer long-term ambient temperatures are associated with lower blood pressure in adults, whereas greater temperature variability is suggested to raise diastolic pressure. Climate-adapted cardiovascular prevention should consider an increase in average temperature and temperature fluctuations in blood pressure management, focusing on urban and metabolically vulnerable groups.