Air travel is expanding world-wide and airports are often at the heart of local economies (I grew up three miles from London Gatwick and my first summer job was in the left luggage office). On the downside, aircraft noise exposure has been linked with physical health problems (e.g. hypertension and cardiovascular disease) and there is growing evidence that noise generated at large airports also affects the mental health of local residents (see NORAH and HYENA, the two largest studies).
Aircraft noise exposure has been linked with physical health problems
We wanted to know whether mental health is similarly affected at smaller, regional airports. This is important as many airlines are switching to fleets of smaller planes flying directly between regional airports, avoiding the major international hubs.
Environmental factors like noise typically produce subtle differences in health outcomes, so we needed a very large dataset to have the best chance of detecting an effect. We linked two administrative datasets (data that are collected for purposes other than research); the 2011 Census records for all residents in our study city of Belfast, Northern Ireland, which provided detailed information on individual and household characteristics, overlaid with noise contours generated as part of the noise monitoring programme at George Best Belfast City Airport.
We found that individuals in high noise areas under the flight path were more likely to have reported poor mental health than those in low noise areas. However, households in high noise areas also tended to be less wealthy and once we accounted for this, we found no evidence that noise was associated with poor mental health. Simply put, wealth rather than aircraft noise best explains these gradients in mental health.
Returning to our main question, the detrimental effects of aircraft noise on mental health found at large airports did not extend to this smaller airport, even at similar average noise levels. Why should this be? We suspect the main answer lies in the timing of noise events. Belfast City Airport does not routinely operate night flights whereas most previously studied airports do, so sleep disturbance (closely linked with mental health) may be the driving factor.
The detrimental effects of aircraft noise on mental health found at large airports did not extend to this smaller airport
The real test of any research finding is whether it can be replicated elsewhere. One way to test the sleep disturbance hypothesis would be to repeat our study across several airports with different numbers and timing of night flights. Accessing information on individual mental health would be the main challenge. In our experience, good datasets – like the administrative datasets we used – already exist, and the key task is to persuade everyone involved that data can safely be used for research to bring public benefit. This study demonstrates the potential of using these large, existing administrative data sets to explore questions we couldn’t answer with smaller available data sets, and it was done without compromising privacy or confidentiality.
Living in a noisy area close to an airport with approximately 40,000 mainly daytime flights annually was not in itself bad for mental health. Therefore, planning decisions for airports up to this size can concentrate more on atmospheric pollution and the effects of noise on aspects of physical health. If further work confirms our suspicion that sleep disturbance drives the noise-mental health association at larger airports, setting sensible curfew hours would strike a balance between the economic benefits and health risks of living close to an airport.