Interview with study manager Prof. Dr. Andreas Seidler: “Noise may also influence the progression of diseases”
Prof. Dr. med. Andreas Seidler, institute director at the technical university of Dresden, manages the study on health risks. In the interview, the epidemiologist and occupational physician tells how he interprets the results and which he found the most surprising.
Which results were surprising for you?
Several! I had not expected, for example, that we would find clear differences for heart attack between the overall group and the partial group of deceased patients: The risk of fatal heart attack was higher in all three noise types than the risk for a new heart attack in general. This makes us wonder if traffic noise may be not only relevant for occurrence of the disease, but also for the progression. I also find it interesting that we found similar, statistically significant exposure-risk relationships for the disease with the most cases, cardiac insufficiency.
Thirdly, the continually high health risks for the indoor levels surprised me. The noise inside the apartments – at the sleeper’s ear – can only be estimated very generally. These insecurities of noise determination should rather blur the risks. Still being able to find increased risks suggests a causative effect of the traffic noise.
In addition to the analysis of the health insurance data, you conducted a deeper survey with some insured persons. How do the answers contribute to your results?
The deeper survey was to determine by the example of cardiac insufficiency whether the results from the health insurance data would be confirmed, or whether known risk factors such as social status, smoking or sports had distorted the results. Considering these interference factors, our results remain nearly unchanged, however. This suggests that the results derived from the health insurance data are highly indicative.
For stroke, it seems as if the health risk would drop with an increasing aviation noise level. How do you explain this?
We should remember two things: One, we see particularly clearly in the case of stroke that the maximum level is relevant as well. We examined the group of persons separately where the continuous noise level was less than 40 decibel, but the maximum noise level above 50 decibel. In this group, we find statistically significantly increase risks. Apparently, the continuous noise level in aviation noise is not enough to describe the aviation noise effect – we also must look at the maximum noise level.
Another reason may be that none of the insured persons was exposed to an aviation noise level above 65 decibel – in contrast to road and railway noise. And when looking at the range above 55 decibel continuous noise level, only about two percent of the included population had an aviation level continuous noise level above this. For railway noise, however, seven percent were above it, and for road traffic noise 26 percent. If higher level values barely occur in aviation noise, or are missing entirely, the entire progress curves become less certain.
For depression, the risk in aviation and railway noise seems to increase first and then drops again in the louder regions. Why might be the reason?
Relatively few persons were exposed to higher noise levels in aviation and also railway noise - much fewer than in case of road noise. This makes the results less secure. However, this is not enough of an explanation. Future studies should examine whether moving plays a role. We have looked at the depression risks for those of whom we knew that they did not move in the last five years: In this group, we found statistically significantly increased depression risks for the highest aviation noise exposure.
Professor Seidler, thank you for the interview!