WHO Guidelines for Community Health

a: The precautionary principle
In all cases, noise should be reduced to the lowest level achievable in a particular situation. Where there is a reasonable possibility that public health will be damaged, action should be taken to protect public health without awaiting full scientific proof.

b :The polluter pays principle
The full costs associated with noise pollution (including monitoring, management, lowering levels and supervision) should be met by those responsible for the source of noise.

c:The prevention principle
Action should be taken where possible to reduce noise at the source. Land-use planning should be guided by an environmental health impact assessment that considers noise as well as other pollutants.

In the case of Ruapuna & the Christchurch City Council the noise seems to have deliberately been increased to the highest level achievable and we can only assume that Council is awaiting scientific proof of illness within this community.