Improving bioaerosol exposure assessments 1 - comparative modelling of 2emissions from different compost ages and activities.

摘要

We present bioaerosol source term concentrations from passive and activecomposting sources and compare emissions from green waste compost aged 1, 2, 4,6, 8, 12 and 16 weeks. Results reveal that the age of compost has little effecton the bioaerosol concentrations emitted for passive windrow sources. Howeveremissions from turning compost during the early stages may be higher than duringthe later stages of the composting process. The bioaerosol emissions frompassive sources were in the range of 103–104 cfu m−3, with releases from activesources typically 1-log higher. We propose improvements to current riskassessment methodologies by examining emission rates and the differences betweentwo air dispersion models for the prediction of downwind bioaerosolconcentrations at off-site points of exposure. The SCREEN3 model provides a moreprecautionary estimate of the source depletion curves of bioaerosol emissions incomparison to ADMS 3.3. The results from both models predict that bioaerosolconcentrations decrease to below typical background concentrations before 250 m,the distance at which the regulator in England and Wales may require a riskassessment to be comple