Pipe Down! Study Finds Link Between Noisy Traffic And Hypertension

So you wake up and there’s a ruckus going on outside your bedroom window.  Honking cars, rumbling trucks, rattling train – the works.  It’s 5:30 a.m., you’re tired and you feel like sticking your head out the window and shaking your fist madly at the din that’s robbed you of those last precious couple hours of sleep.

If this is a familiar scene for you, the following may not come as much of a surprise: A new Swedish study suggests living near noisy traffic may be bad for you.

The study, which appeared last month in the journal Environmental Health, found that people living in homes exposed to high levels of noise from nearby roads were more likely to report having high blood pressure than those living in relatively quiet surroundings.

The researchers from Lund University Hospital surveyed more than 24,000 adults living in the country, using maps and traffic data to estimate the noise levels for each address.

"Road traffic is the most important source of community noise," said the study's lead author, Theo Bodin, in a news release.  "We found that exposure above 60 decibels was associated with high blood pressure among the relatively young and middle-aged, an important risk factor for cardiovascular diseases such as heart attack and stroke."

Past studies have theorized that noise signals the body that it's in a stressful situation. Chronic exposure could result in long-term increases in stress hormone production, heart rate and blood pressure.

While the study noted modest exposure effects in all age groups at average traffic-noise levels below 60 dB(A) – a normal conversation is 60 to 70 dB – the link between reported hypertension and road-noise grew stronger with higher levels of noise among young and middle-aged people.

The researchers noted that many urban dwellers experience traffic noise levels of 55 decibels or more and those numbers is rising.

So what does this mean?  Is that 6:35 a.m. train that roars by your house every morning really elevating your blood pressure?

Well, not necessarily. As the WSJ points out, the Swedish study did not account for the presence of noise barriers or the subject’s floor level, both of which would affect exposure to traffic noise.  As well, other studies have found a significant discrepancy between self-reported hypertension and clinical diagnoses.

Some health experts have also cautioned against jumping to conclusions, saying that factors such as diet and smoking are more important when it comes to blood pressure problems. — Eva Lam