Last Updated: 2003-04-03 11:28:22 -0400 (Reuters Health)

BERLIN (Reuters Health) - People living with high levels of noise from traffic may be more likely than those in more quiet environs to have high blood pressure, German researchers said Thursday.

The investigation by the Robert Koch Institute looked into the effect of noise on 1,700 people living in the German capital.

It found that people who lived in areas with average night-time noise levels of 55 decibels or more were almost twice as likely to be treated for high blood pressure as those who were exposed to average night-time noise levels of less than 50 decibels.

"The study shows that noise pollution raises blood pressure and so has a long-term health impact," said Dr. Heidemarie Wende from the Federal Environment Agency, which commissioned the study.

"The risk of hypertension (high blood pressure) is even greater for people who sleep near open windows," she told Reuters Health.

Study participants completed a questionnaire to assess how much they were disturbed by levels of background noise in their living environment. Participants also gave information on the location of their living and sleeping areas in relation to noise sources.

The researchers used noise maps from the Berlin Senate Department of Urban Development to find out how high the average day- and night-time traffic-noise levels were for those particular areas.

Doctors also interviewed participants about the state of their health during the study and about previous illnesses, including cardiovascular disease, heart attacks, metabolic disorders and allergic diseases.

The researchers found a correlation between levels of night-time background noise and hypertension after doctors took into account other variables that influence blood pressure, including age, body mass and socio-economic factors.

Participants exposed to night-time noise levels higher than 55 decibels were nearly twice as likely to have high blood pressure as those exposed to noise lower than 50 decibels, the researchers said.

The investigation indicated that high noise levels might also be linked to other diseases, such as higher blood fats and migraine, but researchers could not confirm the correlation statistically.