It's two years since I looked at this (on of our sites got a new mast on the roof). I'm not an expert, but my briefing notes (which I've just cut-and-pasted so teh grammar is a bit iffy - I've cut some bits and not adjusted teh grammar properly) are:
Main source of info is the Health Protection Agency website (http://www.hpa.org.uk/, which is an official government agency, and replaced the National Radiological Protection Board (NRPB) and has a specific remit for health effects due to radiation, including non-ionising radiation, eg EMF, eg radio waves).
There is no explicit UK legislation that limits people's exposure to electromagnetic fields, but the enabling legislation regarding Health and Safety (including HASAWA), being general in scope, would encompass risks due to EMFs while at work. HPA claim "inspectors from the Health and Safety Executive accept compliance with the advice from HPA as evidence that exposure to EMFs has been adequately controlled", but I can't find the HSE saying that.
There is a European Directive. The HSE summary is:
The Directive places a number of duties on employers. The main ones being that it:
+ Places a duty on the employer to conduct a risk assessment and calculate EMF strengths.
+ Places a duty on the employer to eliminate or reduce as low as possible the risk of exposure; and where risk can’t be eliminated that measures are devised by the employer to reduce the risk of exposure below ELV (Exposure Limit Value).
+ Requires the employer to provide: the risk assessment to the nominated person responsible for health surveillance;
+ Requires an investigation and medical examination where an employee is ‘detected’ as having been exposed;
+ Records of Health surveillance activities are kept.
and
The Directive puts on a legal footing internationally accepted (ICNIRP) guidelines which are designed to protect people from the acute effects of exposure.
and
ICNIRP is a body of independent scientific experts whose principal aim is to disseminate information and advice on the potential health hazard of exposure to non-ionising radiation including electromagnetic fields. Their guidelines on exposure to EMFs have been developed as a result of an extensive process of expert review of the scientific literature and consultation with other experts and professional bodies.
They also refer to the HPA.
The ICNIRP documents are long and technical and I haven't read them properly. However, HPA summarise the ICNIRP documents as:
At positions where people are exposed to the radio waves from base station antennas, the level of exposure is much more constant over the whole body than when they are exposed to a mobile phone. Under these circumstances, the relevant basic restriction in the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) is that placed on the specific absorption rate (SAR) averaged over the entire body mass. The ICNIRP specifies that this should not exceed 0.4 W kg-1 for workers or 0.08 W kg-1 for the general public.
Whole-body SAR is not very easy to measure practically, consequently the ICNIRP gives a reference level in terms of the power density below which the SAR restriction would be complied with. These reference levels vary with frequency and range from 2 W m-2 to 10 W m-2 for the general public over the radiofrequency range 10 to 300 gigahertz (GHz).
HPA has done monitoring at publically-accessible sites around base stations, including in buildings beneath antennas and in buildings facing antennas on masts or other buildings. There are published reports, but in summary all locations and all sorts of base station the exposure due to the base station was a small fraction of the allowed limits - only exceeding 1% of the allowed limit for small low power, low antenna height micro-cell stations (ie, not what is proposed for our roof).
However, the directive requires that employers "eliminate or reduce as low as possible the risk of exposure", and that would seem to suggest no additional exposure if it can be avoided. Refusing the aerial might prevent the additional exposure (no matter how small).
The operators recognise ICNIRP. There is a voluntary code of practice with 'ten commitments to best siting practice' from the 'Mobile Operators Association' at
http://www.mobilemastinf...st-siting-practice.html. Two of the commitments are:
Assess all radio base stations for international (ICNIRP) compliance for public exposure, and produce a programme for ICNIRP compliance for all radio base stations as recommended by the Independent Expert Group on Mobile Phones (IEGMP).
Provide, as part of planning applications for radio base stations, a certification of compliance with ICNIRP public exposure guidelines.
I suggest we require, as conditions to allowing the antennas:
1: That the operator certifies what will be the maximum exposures at any point within our building, and at any point where maintenance access may be required to the outside of the building will be, as a proportion of current ICNIRP guidelines. When we have those figures, we will make a decision about acceptance or otherwise.
2: That the operator warrants to meet the requirements of the European Directive and all applicable statute at installation, including providing to us risk assessments with calculated EMF figures for any point within our building, and at any point where maintenance access may be required to the outside of the building.
3: That the operator warrants to undertake any additional requirements (including but not limited to further risk assessments, health monitoring etc) mandated by any future change in European directives or UK law, or as required by changes in operation of the equipment.
4: That the operator indemnifies us against any claims or losses from third parties (eg owner of adjacent building who now has antennae beaming in his windows and probably orders of magnitude more exposure than we do).
My criterion for item 1 would be that if the maximum anywhere inside is less than 2% of the limit, then we accept it on the grounds that it is then an installation over which we have some control, rather than (say) an installation on the roof of the next-door building over which we have no control. However, the 2% figure is just me plucking a small number out of the air (though one that, according to the HPA investigations, the operator should be able to easily satisfy).