Department for Environment, Food & Rural Affairs

Noise and Nuisance Policy

Health Effect Based Noise Assessment Methods:
A Review and Feasibility Study
September 1998

3. Noise and health - The Scientific Evidence

3.1: Defining Impacts on Health

"Life is not just being alive, but being well" (MARTIAL AD 40- AD 103: Epigrammata)

Good health is very important to overall quality of life. But what is good health? The World Health Organisation has defined health as follows:

"a state of complete physical and mental and social well-being and not merely the absence of disease or infirmity"(WHO 68)

and explained the requirements of a good healthy environment:

"Good health and well being require a clean and harmonious environment in which physical, physiological, social and aesthetic factors are all given their due importance. The environment should be regarded as a resource for improving living conditions and increasing well being"(WHO 90)

The WHO definition of health does not define what is meant by 'well being'. But how do we measure the well being of an individual or population? Morrell measures health quality statistically as follows;

"People are healthy until they are deemed not to be so. The relative health can be determined by comparative population measures of mortality, morbidity and impairment"(MORELL 97),

Many people might consider the concept of good health to be more dependent on individual expectations than this. The Dutch Health Council proposed yet another definition of good health which could be applied to set 'norms' in relation to both individual and public health and which was not solely based on purely objective measures:

"Health is a dynamic condition of the organism which functions properly and mentally according to the individual's age, sex and general conditions of the population to which the individual belongs, and the current state of science and technology and the related objectives of health care and public health, the beliefs and the cultural patterns of society" (NETHERLANDS 97)

It is clear that definitions of good health vary. Any individual's state of health can vary up or down a scale defined by expectations and cultural needs. Expectations and needs vary and depend on the situation, circumstances and belief systems within the society within which they are formed. Relative health impacts can be only be determined by comparing objective measures against expectations and needs for any particular situation.

In the field of noise and health, policy makers are often faced with considerable uncertainty. First, there is uncertainty as to the direct magnitude of any objectively measurable effects on health. Second, there is even confusion in the literature about the way these effects are defined. This makes the task of balancing the costs of noise control action against the likely outcome in terms of health effects problematical.

The main emphasis of current noise standards and regulations is annoyance. This is probably because the most immediate consequence of unwanted environmental noise exposure is complaints. Many airports in particular have a long standing history of persistent noise complaints from a significant minority of noise exposed residents. Individuals are perfectly competent to decide whether they are 'annoyed' or not, or whether they believe their sleep has been disturbed. For this reason, annoyance has formed a natural and immediate topic for research over many years. In the sense that annoyance and perceived sleep disturbance can interfere with perceived 'quality of life', then these effects are already included in the broadest definitions of health effects.

On the other hand, annoyance and perceived sleep disturbance are in any sense of the term, much less 'serious' health effects than cardiovascular or mental disorders would be, if they occurred. The problem here is that individuals generally have no way of knowing whether noise has had any effect on their general health or not, as this can only be determined by observations of increased morbidity in the general population. To the extent that proven effects on cardiovascular or mental health would be likely to be perceived as much more 'serious' impacts on general health than mere annoyance or perceived sleep disturbance, then any greater emphasis on these topics for the future must be encouraged. A statement that x or y percent of the population would be likely to suffer from some life threatening disease as a result of stress caused by environmental noise would form a much more transparent basis for any future policy decisions than current generalities about the relative likelihood of annoyance underlying many existing standards and regulations.

It is important to understand that individuals cannot make reliable judgements about the precise causes of any 'serious' adverse health effects that might otherwise be attributable to excessive noise because, if such effects exist, they appear to be quite weak and might only be contributory to other causal factors. It is effectively impossible to resolve the complex mix of separate potential risk factors and their combination in any individual case. For this reason, it is necessary to talk about increased or decreased risk rather than precise cause, and only large scale studies looking at the progressing health status of groups of individuals under changing environmental conditions can discover the truth about these matters. Even in the case of sleep disturbance, which might otherwise seem to be an obvious and easily reported effect, it turns out that individuals are generally not very good at being able to report precisely what happened on a previous night. While this is not surprising in the sense that people cannot be expected to recall what happened when they were mostly asleep, it is not helpful in being able to obtain definitive measures of the relative magnitudes and importances of these effects. People's perceptions of the relative magnitudes of these effects might be just as important as their actual magnitudes. Given the present state of scientific knowledge, and subject to future research, the possible adverse health effects of environmental noise might best be considered as an issue of public perception rather more than as an issue involving a direct and proven health risk.

In essence, to judge an impact on health, policy makers will need to know;

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Published 12 September 2000
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