[holding answer 18 December 2008]: The Environment Agency published a policy statement on composting and the potential health effects from bioaerosols produced as a result of the composting process in 2001. This set out its requirement for site specific bioaerosol risk assessments (for proposed composting facilities within 250 metres of dwellings or workplaces). The figure represents a precautionary measure and the point at which a site specific bio-aerosol risk assessment is required. The policy applies to all composting activities irrespective of waste type. Kitchen food waste cannot be composted in open windrows.
Since then, further work in this area has been undertaken by various parties. This has reiterated that there is insufficient information to determine the risk to human health from bioaerosols from composting. It has recommended that the trigger distance remain in place. This is a precautionary approach, based on research which has shown that bioaerosols should reduce to background levels within 250m. In 2007 the Environment Agency issued a revised policy statement which re-affirmed the need for site specific bioaerosol risk assessments to be carried out.
[holding answer 18 December 2008]: The Environment Agency continues to work closely with the Health and Safety Executive on bioaerosols from composting sites. For example, the Environment Agency has recently published a science report based on work carried out by the Health and Safety Laboratory, "Bioaerosols in waste composting: deriving source terms and characterising profiles" (HSL labs). Published December 2008 as Science report SC040021/SR2.
[holding answer 18 December 2008]: Following a further review of available research the Environment Agency maintained its precautionary approach in its policy statement published in October 2007.
This requires bioaerosol risk assessments to take place if a proposed composting site is within 250 metres of dwellings or workplaces. Wind turbulence modelling has limited value for modelling dispersion of bioaerosols and was not used to formulate the position.
However in addition to conducting its own further research with the Health and Safety Laboratory, the Environment Agency recognises the value that might be added by work carried out by others and has arranged for this work to be peer reviewed.