Comparison of three studies of aircraft noise and psychiatric hospital admissions conducted in the same area.

Two earlier studies conducted in the vicinity of London (Heathrow) Airport compared the rate of admissions to a psychiatric hospital from areas exposed to different levels of aircraft noise. Their methods and results were not identical. A third study, reported here, examined standardized rates of admission to the same hospital for a longer period and for a larger area divided into 4 bands of aircraft noise. Statistically significant trends of decreasing admission with increasing noise levels were found. Comparisons between the investigations show how the contradictory results are related to the methods used and the accuracy of the data, and that caution should be exercised in formulating conclusions from exploratory research.