Browsing by Author "Drew, Gillian H."
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Item Open Access Appropriateness of selecting different averaging times for modelling chronic and acute exposure to environmental odours(2007-04-01T00:00:00Z) Drew, Gillian H.; Smith, Richard; Gerard, Valerie; Burge, C.; Lowe, M.; Kinnersley, R.; Sneath, R.; Longhurst, Philip J.Odour emissions are episodic, characterised by periods of high emission rates, interspersed with periods of low emissions. It is frequently the short term, high concentration peaks that result in annoyance in the surrounding population. Dispersion modelling is accepted as a useful tool for odour impact assessment, and two approaches can be adopted. The first approach of modelling the hourly average concentration can underestimate total odour concentration peaks, resulting in annoyance and complaints. The second modelling approach involves the use of short averaging times. This study assesses the appropriateness of using different averaging times to model the dispersion of odour from a landfill site. We also examine perception of odour in the community in conjunction with the modelled odour dispersal, by using community monitors to record incidents of odour. The results show that with the shorter averaging times, the modelled pattern of dispersal reflects the pattern of observed odour incidents recorded in the community monitoring database, with the modelled odour dispersing further in a north easterly direction. Therefore, the current regulatory method of dispersion modelling, using hourly averaging times, is less successful at capturing peak concentrations, and does not capture the pattern of odour emission as indicated by the community monitoring database. The use of short averaging times is therefore of greater value in predicting the likely nuisance impact of an odour source and in framing appropriate regulatory controls.Item Open Access Biodrying for mechanical-biological treatment of wastes: A review of process science and engineering(Elsevier Science B.V., Amsterdam., 2009-06-01T00:00:00Z) Velis, C. A.; Longhurst, Philip J.; Drew, Gillian H.; Smith, Richard; Pollard, Simon J. T.Biodrying is a variation of aerobic decomposition, used within mechanical–biological treatment (MBT) plants to dry and partially stabilise residual municipal waste. Biodrying MBT plants can produce a high quality solid recovered fuel (SRF), high in biomass content. Here, process objectives, operating principles, reactor designs, parameters for process monitoring and control, and their effect on biodried output quality are critically examined. Within the biodrying reactors, waste is dried by air convection, the necessary heat provided by exothermic decomposition of the readily decomposable waste fraction. Biodrying is distinct from composting in attempting to dry and preserve most of biomass content of the waste matrix, rather than fully stabilise it. Commercial process cycles are completed within 7–15 days, with mostly H2O(g) and CO2 loses of ca. 25–30% w/w, leading to moisture contents of <20% w/w. High airflow rate and dehumidifying of re-circulated process air provides for effective drying. We anticipate this review will be of value to MBT process operators, regulators and end-users oItem Open Access The challenges, uncertainties and opportunities of bioaerosol dispersion modelling from open composting facilities(WIT Press, 2017-08-06) Williams, Ben; Hayes, Enda; Nasir, Zaheer A.; Rolph, Catherine A.; Jackson, Simon; Khera, Shagun; Bennett, Alan; Gladding, Toni; Drew, Gillian H.; Tyrrel, Sean F.Bioaerosols are ubiquitous organic particles that comprise viruses, bacteria and coarser fractions of organic matter. Known to adversely affect human health, the impact of bioaerosols on a population often manifests as outbreaks of illnesses such as Legionnaires Disease and Q fever, although the concentrations and environmental conditions in which these impacts occur are not well understood. Bioaerosol concentrations vary from source to source, but specific human activities such as water treatment, intensive agriculture and composting facilitate the generation of bioaerosol concentrations many times higher than natural background levels. Bioaerosols are not considered ‘traditional’ pollutants in the same way as PM10, PM2.5, and gases such as NO2, and consequently dispersion models do not include a bespoke method for their assessment. As identified in previous studies, priority areas for improving the robustness of these dispersion models include: 1) the development of bespoke monitoring studies designed to generate accurate modelling input data; 2) the publication of a robust emissions inventory; 3) a code of practice to provide guidelines for consistent bioaerosol modelling practices; and 4) a greater understanding of background bioaerosol emissions. The aim of this research project, funded by the Natural Environmental Research Council (NERC), is to address these key areas through a better understanding of the generation, concentration and potential dispersion of bioaerosols from intensive agricultural and biowaste facilities, using case studies developed at specific locations within the UK. The objective is to further refine existing bioaerosol monitoring and modelling guidelines to provide a more robust framework for regulating authorities and site operators. This contribution outlines the gaps that hinder robust dispersion modelling, and describes the on-site bioaerosol data collection methods used in the study, explaining how they might be used to close these gaps. Examples of bioaerosol dispersion modelled using ADMS 5 are presented and discussed.Item Open Access Delivering organisational adaptation through legislative mechanisms: Evidence from the Adaptation Reporting Power (Climate Change Act 2008)(Elsevier, 2016-10-14) Jude, Simon R.; Drew, Gillian H.; Pollard, Simon J. T.; Rocks, Sophie A.; Jenkinson, K.; Lamb, R.There is increasing recognition that organisations, particularly in key infrastructure sectors, are potentially vulnerable to climate change and extreme weather events, and require organisational responses to ensure they are resilient and adaptive. However, detailed evidence of how adaptation is facilitated, implemented and reported, particularly through legislative mechanisms is lacking. The United Kingdom Climate Change Act (2008), introduced the Adaptation Reporting Power, enabling the Government to direct so-called reporting authorities to report their climate change risks and adaptation plans. We describe the authors' unique role and experience supporting the Department for Environment, Food and Rural Affairs (Defra) during the Adaptation Reporting Power's first round. An evaluation framework, used to review the adaptation reports, is presented alongside evidence on how the process provides new insights into adaptation activities and triggered organisational change in 78% of reporting authorities, including the embedding of climate risk and adaptation issues. The role of legislative mechanisms and risk-based approaches in driving and delivering adaptation is discussed alongside future research needs, including the development of organisational maturity models to determine resilient and well adapting organisations. The Adaptation Reporting Power process provides a basis for similar initiatives in other countries, although a clear engagement strategy to ensure buy-in to the process and research on its long-term legacy, including the potential merits of voluntary approaches, is required.Item Open Access Dispersion of bioaerosols from composting facilities.(2006-09-01T00:00:00Z) Drew, Gillian H.; Tamer Vestlund, Asli; Taha, M. P. M.; Smith, Richard; Longhurst, Philip J.; Kinnersley, R.; Pollard, Simon J. T.The promotion of composting as an option for sustainable waste management has raised concerns regarding public health impacts of exposures to potentially hazardous bioaerosols. Recent source term experiments show that bioaerosol emissions are episodic and that peak emissions are related to compost agitation. The Environment Agency requires risk assessments for facilities that have sensitive receptors within 250m of their boundary. In order to improve current risk assessment methodologies, improved predictions of bioaerosol dispersal are required. Dispersion modelling has been successfully used to determine dispersion of odours from waste management. In this paper, bioaerosol concentration data measured at a composting facility is analysed in an ongoing series of model experiments, using the ADMS air dispersion model. Initial modelling results reveal that the concentrations of bioaerosols decrease rapidly with distance from the site, although under certain circumstances, it is possible that higher concentrations may still be present at 200m from the site boundary. However, dispersion models are not yet able to take into account all the properties of bioaerosols, in particular, their viability and their ability to aggregate and form clumps, which will affect the rate of dispersal. A series of experiments were designed to examine how the options within dispersion model affect the dispersion of bioaerosols and under which circumstances high concentrations may disperse to sensitive receptors. The results will be compared with bioaerosol measurements taken downwind of a composting facility, to determine the accuracy of the model predictions. This is the first stage in an attempt to design a best practice method for modelling bioaerosols.Item Open Access Endotoxin emissions from commercial composting activities(BioMed Central, 2009-12-21T00:00:00Z) Deacon, Lewis J.; Pankhurst, Louise J.; Liu, Jian; Drew, Gillian H.; Hayes, Enda T.; Jackson, Simon; Longhurst, James; Longhurst, Philip J.; Pollard, Simon J. T.; Tyrrel, Sean F.This paper describes an exploratory study of endotoxin emissions and dispersal from a commercial composting facility. Replicated samples of air were taken by filtration at different locations around the facility on 10 occasions. Measurements were made of endotoxin and associated culturable microorganisms. The inflammatory response of cell cultures exposed to extracts from the filters was measured. Endotoxin was detected in elevated concentrations close to composting activities. A secondary peak, of lesser magnitude than the peak at source was detected at 100-150 m downwind of the site boundary. Unexpectedly high concentrations of endotoxin were measured at the most distant downwind sampling point. Extracted endotoxin was found to stimulate human monocytes and a human lung epithelial cell line to produce significant amounts of pro- inflammatory cytokines. On a weight basis, endotoxin extracted from the composting source has a greater inflammatory cytokine inducing effect than commercial E. coli endotoxin.Item Open Access Enumerating actinomycetes in compost bioaerosols at source—Use of soil compost agar to address plate ‘mask(2007-07-01T00:00:00Z) Taha, M. P. M.; Drew, Gillian H.; Tamer Vestlund, Asli; Aldred, David; Longhurst, Philip J.; Pollard, Simon J. T.Actinomycetes are the dominant bacteria isolated from bioaerosols sampled at composting facilities. Here, a novel method for the isolation of actinomycetes is reported, overcoming masking of conventional agar plates, as well as reducing analysis time and costs. Repeatable and reliable actinomycetes growth was best achieved using a soil compost media at an incubation temperature of 44 °C and 7 days’ incubation. The results are of particular value to waste management operators and their advisors undertaking regulatory risk assessments that support environmental approvals for compost facilitiItem Open Access Evaluating the quality of bioaerosol risk assessments for composting facilities in England and Wales(Elsevier Science B.V., Amsterdam., 2009-07-01T00:00:00Z) Drew, Gillian H.; Jordinson, G. M.; Smith, M. A.; Pollard, Simon J. T.A critical evaluation of 44 environmental risk assessments for composting facilities, submitted in support of environmental permits or exemption from licensing is presented. Assessments were scored semi-quantitatively, in triplicate, by reference to 11 generic and 11 bioaerosol-specific risk assessment attributes developed from existing regulatory guidance. Radar plots of the two attribute groups illustrate where opportunities for improvements exist, and are being used to inform regulatory guidance to the operators of composting facilities and their professional advisors. Aspects of the regulatory risk assessments requiring attention include (i) descriptions of the limitations and uncertainties within risk analyses, (ii) presentation of methodological details of sampling and analysis, and (iii) the provision of background information.Item Open Access Identifying uncertainty in environmental risk assessments: the development of a novel typology and Its implications for risk characterisation(Taylor & Francis, 2014-12-31T00:00:00Z) Skinner, Daniel J. C.; Rocks, Sophie A.; Pollard, Simon J. T.; Drew, Gillian H.Environmental risk analysts need to draw from a clear typology of uncertainties when qualifying risk estimates and/or significance statements about risk. However, categorisations of uncertainty within existing typologies are largely overlapping, contradictory, and subjective, and many typologies are not designed with environmental risk assessments (ERAs) in mind. In an attempt to rectify these issues, this research provides a new categorisation of uncertainties based, for the first time, on the appraisal of a large subset of ERAs, namely 171 peer-reviewed environmental weight-of-evidence assessments. Using this dataset, a defensible typology consisting of seven types of uncertainty (data, language, system, extrapolation, variability, model, and decision) and 20 related sub-types is developed. Relationships between uncertainties and the techniques used to manage them are also identified and statistically evaluated. A highly preferred uncertainty management option is to take no action when faced with uncertainty, although where techniques are applied they are commensurate with the uncertainty in question. Key observations are applied in the form of guidance for dealing with uncertainty, demonstrated through ERAs of genetically modified higher plants in the European Union. The presented typology and accompanying guidance will have positive implications for the identification, prioritisation, and management of uncertainty during risk characterisation.Item Open Access Improving bioaerosol exposure assessments 1 - comparative modelling of 2 emissions from different compost ages and activities.(2007-07-01T00:00:00Z) Taha, M. P. M.; Drew, Gillian H.; Tamer Vestlund, Asli; Hewings, G.; Jordinson, G. M.; Longhurst, Philip J.; Pollard, Simon J. T.We present bioaerosol source term concentrations from passive and active composting 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 effect on the bioaerosol concentrations emitted for passive windrow sources. However emissions from turning compost during the early stages may be higher than during the later stages of the composting process. The bioaerosol emissions from passive sources were in the range of 103–104 cfu m−3, with releases from active sources typically 1-log higher. We propose improvements to current risk assessment methodologies by examining emission rates and the differences between two air dispersion models for the prediction of downwind bioaerosol concentrations at off-site points of exposure. The SCREEN3 model provides a more precautionary estimate of the source depletion curves of bioaerosol emissions in comparison to ADMS 3.3. The results from both models predict that bioaerosol concentrations decrease to below typical background concentrations before 250 m, the distance at which the regulator in England and Wales may require a risk assessment to be compleItem Open Access Modelling human exposures to air pollution control (APC) residues released from landfills in England and Wales(Elsevier Science B.V., Amsterdam., 2006-05-01T00:00:00Z) Macleod, Christopher; Duarte-Davidson, Raquel; Fisher, Bernard; Ng, Betty; Willey, David; Shi, Ji Ping; Martin, Ian; Drew, Gillian H.; Pollard, Simon J. T.Human exposures to air pollution control (APC) residues released from 6 landfills were modeled and assessed. Following a qualitative risk characterisation, direct and indirect exposures were quantified. Site-specific air dispersion modelling was conducted for PM10, PCDDs/PCDFs, Pb, Cd, As and CrVI concentrations at the closest residential points of exposure for 4 landfill sites accepting, in total, 75 %w/w of the APC residues disposed of in 2000-2001 (UK). Inhalation risks, assessed by reference to air quality standards at residential exposure points were assessed as insignificant. Preliminary modelling suggested that indirect exposures from PCDDs/PCDFs at the 95th percentile level for the site where APC deposition rates were highest, exceed the tolerable daily soil intake (TDSI) but warrant further study given model limitations. These results offer an initial screen of the significance of potential risks from APC disposal, which is of value in addressing concerns about the uncertainty of potential risks to human health from bulk APC disposal at strategic locations.Item Open Access Morphological classification of bioaerosols from composting using scanning electron microscopy(2014-07-31T00:00:00Z) Tamer Vestlund, Asli; Al-Ashaab, R.; Tyrrel, Sean F.; Longhurst, Philip J.; Pollard, Simon J. T.; Drew, Gillian H.This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samples were analysed using scanning electron microscopy. Particles were released mainly as small (<1 μm) single, spherical cells, followed by larger (>1 μm) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2-3 particles as opposed to chains, and were <10 μm in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors.Item Open Access Predicting Aspergillus fumigatus exposure from composting facilities using a dispersion model: a conditional calibration and validation(Elsevier, 2017-01) Douglas, Philippa; Tyrrel, Sean F.; Kinnersley, Robert P.; Whelan, M. J.; Longhurst, Philip J.; Hansell, Anna L.; Walsh, K.; Pollard, Simon J. T.; Drew, Gillian H.Bioaerosols are released in elevated quantities from composting facilities and are associated with negative health effects, although dose-response relationships are unclear. Exposure levels are difficult to quantify as established sampling methods are costly, time-consuming and current data provide limited temporal and spatial information. Confidence in dispersion model outputs in this context would be advantageous to provide a more detailed exposure assessment. We present the calibration and validation of a recognised atmospheric dispersion model (ADMS) for bioaerosol exposure assessments. The model was calibrated by a trial and error optimisation of observed Aspergillus fumigatus concentrations at different locations around a composting site. Validation was performed using a second dataset of measured concentrations for a different site. The best fit between modelled and measured data was achieved when emissions were represented as a single area source, with a temperature of 29 °C. Predicted bioaerosol concentrations were within an order of magnitude of measured values (1000–10,000 CFU/m3) at the validation site, once minor adjustments were made to reflect local differences between the sites (r2 > 0.7 at 150, 300, 500 and 600 m downwind of source). Results suggest that calibrated dispersion modelling can be applied to make reasonable predictions of bioaerosol exposures at multiple sites and may be used to inform site regulation and operational management.Item Open Access Production and quality assurance of solid recovered fuels using Mechanical- Biological Treatment (MBT) of waste: a comprehensive assessment(Taylor & Francis, 2010-12-01T00:00:00Z) Velis, C. A.; Longhurst, Philip J.; Drew, Gillian H.; Smith, Richard; Pollard, Simon J. T.The move from disposal-led waste management to resource management demands an ability to map flows of the properties of waste. Here, we provide a comprehensive review of how mechanical-biological treatment (MBT) plants, and the unit processes that comprise them, perform in relation to management of material flows, while transforming inputs into output fractions. Focus is placed on the properties relating to the quality of MBT-derived fuels. Quality management initiatives for refuse-derived fuels (RDF) or solid recovered fuels (SRF) are reviewed and SRF quality from MBT plants is assessed through a statistical analysis of published data. This can provide a basis for a targeted reduction in pollution load from solid MBT outputs and subsequent end-user emissions. Our analysis, among else, (1) verifies the difficulty of chemical separation solely by mechanical means; (2) illustrates the trade-off between achieving a high quality of recoverable outputs and the quantity/properties of reject material; and (3) indicates that SRF quality could respond to legislative requirements and market needs, if specific improvements (reduction of Cl, Cu, and Pb content) are achieved. Further research could enhance the confidence in the ability of MBT plants to produce a quality-assured SRF suitable for specific end-users, without contradicting the wider requirement for an overall sustainable management of resources.Item Open Access Progress towards a best practice method for modelling dispersion of bioaerosols from composting facilities(2007-10-01T00:00:00Z) Drew, Gillian H.; Tamer Vestlund, Asli; Jordinson, G.; Taha, M. P. M.; Smith, Richard; Tyrrel, Sean F.; Longhurst, Philip J.; Pollard, Simon J. T.The promotion of composting in the UK as a sustainable waste management option has led to concerns regarding exposure of the public to potentially harmful emissions of airborne micro-organisms or bioaerosols. In response to public concerns, the Environment Agency in England and Wales requires a risk assessment for any licensed composting facility that has a sensitive receptor within 250m of the site boundary. An ongoing programme of studies in association with the Environment Agency has begun to explore methods to improve exposure assessments for bioaerosols. Our results have shown that is is possible to use air dispersion models for estimating downwind concentrations of bioaerosols, and the more advanced modelling options, such as the use of intermittent emission rates, result in lower downwind concentrations. Current risk assessments may be over-estimating the exposure of receptors to bioaerosols from composting, however further studies are needed to validate the results presented here. 1. INTRODUCTION The promotion of composting in the UK as a more sustainable waste management option has led to concerns regarding exposure of the public to potentially harmful emissions of airborne microorganisms or bioaerosols. The composting process is reliant on various micro-organisms, such as bacteria and fungi, to break down the organic matter. However, if as a result of composting operations these micro-organisms become airborne, may be breathed in, and due to their small size, can penetrate deep into the human respiratory system. Conditions such as farmer's lung disease and aspergillosis (Latgé, 1999) have been linked to high concentrations of bioaerosols, although dose-response relationships are not well defined. In response to public concerns, the Environment Agency in England and Wales requires a risk assessment for any licensed composting facility that has a sensitive receptor within 250m of theItem Open Access Sensitivity of predicted bioaerosol exposure from open windrow composting facilities to ADMS dispersion model parameters(Elsevier, 2016-10-13) Douglas, Philippa; Tyrrel, Sean; Kinnersley, Robert P.; Whelan, M. J.; Longhurst, Philip J.; Walsh, K.; Pollard, Simon J. T.; Drew, Gillian H.Bioaerosols are released in elevated quantities from composting facilities and are associated with negative health effects, although dose-response relationships are not well understood, and require improved exposure classification. Dispersion modelling has great potential to improve exposure classification, but has not yet been extensively used or validated in this context. We present a sensitivity analysis of the ADMS dispersion model specific to input parameter ranges relevant to bioaerosol emissions from open windrow composting. This analysis provides an aid for model calibration by prioritising parameter adjustment and targeting independent parameter estimation. Results showed that predicted exposure was most sensitive to the wet and dry deposition modules and the majority of parameters relating to emission source characteristics, including pollutant emission velocity, source geometry and source height. This research improves understanding of the accuracy of model input data required to provide more reliable exposure predictions.Item Open Access Sources of airborne endotoxins in ambient air and exposure of nearby communities - a review(MDPI, 2018-09-26) Rolph, Catherine A.; Gwyther, Ceri L.; Tyrrel, Sean F.; Nasir, Zaheer A.; Drew, Gillian H.; Jackson, Simon K.; Khera, Shagun; Hayes, Enda T.; Williams, Ben; Bennett, Allan; Collins, Samuel; Walsh, Kerry; Kinnersley, Rob; Gladding, Toni L.Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is complicated due to a wide range of different parameters including sampling approaches, temperature, and site activity, demonstrating the need for a standardised methodology and improved guidance. Thorough characterisation of ambient endotoxin levels and modelling of endotoxin from pollution sources is needed to help inform future policy and support a robust health-based risk assessment process.Item Open Access Street-scale dispersion modelling framework of road-traffic derived air pollution in Hanoi, Vietnam(Elsevier, 2023-06-26) Ngo, Khoi Quang; Le, Hoang Anh; Bang, HQ; Harris, Neil R. P.; Drew, Gillian H.; Mead, Mohammed IqbalTraffic is an important source of air pollution in Vietnamese cities. The spatio-temporal variation of air pollution derived from traffic is poorly understood. Application of dispersion modelling can help but is hindered by the local scarcity of suitable input data. This study fills the data gap, by establishing a framework employing open-access global data to model emission from traffic activities in Hanoi. The outlined methodology explicitly defines road sources, calculates their emission, and employs background pollution profiles from Copernicus Atmospheric Monitoring Service (CAMS) to produce street-scale distribution maps for CO, PM10 and PM2.5. Pollution hotspots are found near major traffic flows with the highest hourly average CO, PM10 and PM2.5 concentrations at 1206, 87.5 and 61.5 μgm−3, respectively. The relationship between concentrations and properties of the road network is assessed. Motorcycles are the main emitters of the traffic sector. Emission from Heavy Good Vehicles dominate during the night, with contribution percentages increase as it gets further away from the city core. Modelled concentrations are underestimated mainly due to low vehicular emission factor. Adjusting emission factors according to vehicle quality in Vietnam greatly improves agreement. The presence of non-traffic emission sources contributes to the model underestimation. Results for comparisons of daily averaged PM values are broadly in agreement between models and observations; however, diurnal patters are skewed. This results partly from the uncertainties linked with background pollution levels from CAMS, and partly from non-traffic sources which are not accounted for here. Further work is needed to assess the use of CAMS's concentrations in Vietnam. Meteorological input contributes to the temporal disagreement between the model and observations. The impact is most noticeable with CO concentrations during morning traffic rush hours. This study recommends approaches to improve input for future model iterations and encourage applications of dispersion modelling studies in similar economic settings.Item Open Access Use of dispersion modelling for Environmental Impact Assessment of biological air pollution from composting: progress, problems and prospects(Elsevier, 2017-09-07) Douglas, P.; Hayes, E. T.; Williams, W. B.; Tyrrel, Sean F.; Kinnersley, R. P.; Walsh, K.; O'Driscoll, M.; Longhurst, Philip J.; Pollard, Simon J. T.; Drew, Gillian H.With the increase in composting as a sustainable waste management option, biological air pollution (bioaerosols) from composting facilities have become a cause of increasing concern due to their potential health impacts. Estimating community exposure to bioaerosols is problematic due to limitations in current monitoring methods. Atmospheric dispersion modelling can be used to estimate exposure concentrations, however several issues arise from the lack of appropriate bioaerosol data to use as inputs into models, and the complexity of the emission sources at composting facilities. This paper analyses current progress in using dispersion models for bioaerosols, examines the remaining problems and provides recommendations for future prospects in this area. A key finding is the urgent need for guidance for model users to ensure consistent bioaerosol modelling practices.