The Impact on Blood Pressure of a Short-Term Change in Indoor Temperature

The aim of this study is to evaluate the impact on blood pressure (BP) of a 10°C change in room temperature (between 18°C and 28°C).

A total of 112 volunteers, 56 males and 56 females, 55 with and 57 without hypertension, were enrolled in the study. First, the participants were placed in a 25°C room. Second, they were randomly assigned to either a 28°C (group A) or an 18°C room (group B). Finally, they were moved from the 28°C to the 18°C room, or vice versa. They stayed in each room for 20 minutes. Seated BP was measured at the 17th and 19th minute in each room, and the average was used. The difference in the subject's BP between the second two rooms was recorded as delta BP.

The baseline systolic BP (SBP), age, gender distribution, and incidence of hypertension were similar between the two groups. In group A, the decrease in room temperature of 10°C induced a mean rise in SBP of 4.1 mmHg. In group B, the increase of 10°C caused SBP to decrease by 4.0 mmHg. When compared with the group without hypertension, the group with hypertension had a significantly higher rise in mean SBP (6.8 vs 1.2 mmHg) as a result of the decrease in temperature and a significantly higher drop in SBP (7.3 vs 1.2 mmHg) as a result of the increase in temperature. The participants in the group with hypertension were older.

A 10°C change in room temperature, from 18°C to 28°C, for 20 min can cause a significant change in SBP. The extent of this change is more obvious in the older group.