by Daniel Fink, MD, Chair, The Quiet Coalition

The Brittanica website defines a natural experiment as an:

[O]bservational study in which an event or a situation that allows for the random or seemingly random assignment of study subjects to different groups is exploited to answer a particular question. Natural experiments are often used to study situations in which controlled experimentation is not possible, such as when an exposure of interest cannot be practically or ethically assigned to research subjects.

One recent natural experimental situation occurred during the COVID lockdowns, with the decrease in transportation noise allowing studies to be done about the effect of quiet on birds, those in cities listening to birds, and marine mammals.

Another report, just published, extends the experimental population to humans, with the independent variable being aircraft noise exposure and the dependent variable being various measures of cardiovascular risk. In the respected American Heart Association journal Hypertension, the researchers found that subjects with hypertension and long term aircraft noise exposure >65 decibels had decreases in blood pressure and pulse wave velocity (a measure of arterial stiffness) after the COVID lockdown in April 2020. Lesser degrees of blood pressure and pulse wave velocity were found in control subjects who were not exposed to aircraft noise.

An editorial by pioneering cardiovascular health researcher Thomas Münzel and colleagues discusses the importance of this study. They noted three important implications of the study:

  1. The results add to the evidence that aircraft noise exposure is a public health threat;
  2. The study confirms mechanisms of aircraft noise-induced cardiovascular diseases; and
  3. The results show that even short term reductions in aircraft noise may have the potential to reverse unfavorable cardiovascular health effects of aircraft noise.

We hope the study and accompanying editorial will spur further efforts to manufacture quieter aircraft and regulatory efforts to limit the impacts of aircraft noise on communities living near airports and under flight paths.