• noise
• mental health

Readers may be interested to know that there are other recent studies that have provided equivocal evidence concerning the effects of environmental noise on children’s mental health that have not been cited in the article by Lercher et al, published in the June 2002 issue of Occupational and Environmental Medicine.¹ These new results need to be considered in the light of fact there has not been clear research evidence to support or dispute whether noise exposure in linked to mental health problems in children.

We have found inconsistent mental health results in our three recent studies examining the impact of aircraft noise on child health around Heathrow airport.^2–4 In the West London Schools Study,⁴ aircraft noise was weakly associated with hyperactivity and psychological morbidity as measured by the Strengths and Difficulties Questionnaire (SDQ⁵) completed by parents.

The SDQ is one of the most widely used psychometrically valid instruments to detect psychological morbidity in children in both the UK and internationally. However, in our other two studies using both the parent completed SDQ, the teacher completed Student Behaviour Checklist, and child self reported Depression (Child Depression Inventory, CDI) and Anxiety (Revised Child Manifest Anxiety Scale) we did not find any association between mental ill health and aircraft noise exposure.^2,3

The Austrian results should be placed within the context of existing studies with respect to two points: (1) the construct being measured in the Austrian study; and (2) the small effect size and inconsistency with previous research.

In the Heathrow studies we used internationally recognised child mental health screening tools, that have equivalent psychometric properties to the KINDL (only used in German speaking countries). It is worth noting that the KINDL is normally defined as a “valid and reliable index of quality of life”,⁶ rather than a sensitive screening tool to detect specific mental health problems. It is possible that the mental health results reported by Lercher and colleagues are tapping into impaired quality of life and wellbeing, rather than a precise mental health outcome such as “depression”. The definition of “mental health” used by the authors needs to be clarified. The fact that the Austrian results do not replicate our Heathrow results raises the question: Does the KINDL measure wellbeing and quality of life rather than mental health? Furthermore, teacher reports of classroom adjustment would not normally be classified as a “mental health”. Perhaps it might be more accurate to conclude from the Austrian research that: “ambient levels of noise in the community are associated with decreased quality of life and poorer classroom behaviour (rather than ‘mental health’) in elementary school children”.

In summary, we feel that new research is necessary to provide further evidence about the effects of noise on child mental health. Even though Lercher and colleagues have taken the field of research forward with their two stage study design strategy, there is still more work to be done to clarify the terminology and measurement of mental health in the field of non-auditory health effects of noise. Specifically, a clear definitional and operational distinction needs to be made between stress/wellbeing/quality of life and mental health.