Dr Peter Irga is a Post-Doctoral Research fellow in air quality research and core member of the Plants and Environmental Quality Research Group at UTS.
Peter is an internationally recognised expert in indoor air pollution and the main technologies and protocols used for air pollution monitoring, with specialist knowledge on pathogenic fungal spores and contaminated buildings.
His current research interests lie in the application of atmospheric science to inform policy on air quality, the relationship between air quality and health, and on the linkages between air quality and climate change.
He has also worked extensively on projects involving optimizing plants potential to improve air quality, especially through biotechnology. Peter’s recent work is focused on the use biotechnology for the reduction of air pollutants, namely biofilter systems.
Can supervise: YES
Key research areas
- Urban aerobiology, with an emphasis on pathogenic fungi
- Horticultural biotechnology for mitigating air pollutants
- Functional active green wall technology development
- Botanical systems for improving urban amenity: noise attenuation, aesthetics, water use, temperature
- Geospatial analysis of the determinants of urban air quality
- Urban agriculture, urban forestry, urban greening
Since 2012, I have lectured and run laboratory practical classes in the UTS subjects:
- Experimental Design and Sampling (91110)
- General Microbiology (91314)
- Environmental Forensics (91159)
- Environmental Remediation (91159)
- Epidemiology and Public Health Microbiology (91330)
- Air and Noise Pollution (49049)
- Decentralised Environmental Systems (49127)
Abdo, P, Huynh, BP, Irga, PJ & Torpy, FR 2019, 'Evaluation of air flow through an active green wall biofilter', Urban Forestry and Urban Greening, vol. 41, pp. 75-84.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier GmbH Green walls show promise as active bio-filters to improve indoor air quality by removing both gaseous and particulate air pollutants. The current work represents a detailed assessment of airflow through an active green wall module. Airflow distribution through the module, the effect of wetting the substrate, and the effect of introducing a cover to the module's open top face were investigated, with the aim to improve the module's design and achieve more appropriate and effective airflow. Four cases of both planted and unplanted modules under both dry and wet conditions are considered. This work's primary observation is that more air will pass through a typical green wall substrate, and hence become cleansed, when the substrate is saturated wet more than when it is dry. The increase was substantial at approximately 50% more with 14.9 ± 0.2 L/s total air flow rate passing through the wet planted module versus 10 ± 0.2 L/s when dry. Reducing the 15.5 ± 0.75% of airflow passing through the module's open top face was found to be essential to maximize the bio-filtration capacity. Adding a top cover to the module having six 10 mm holes for irrigation decreased the airflow through the top by 6 ± 0.75%, and directed it through the filter increasing the percentage of air flow passing through the front openings from 79 ± 4% to 85 ± 4%.
Douglas, ANJ, Irga, PJ & Torpy, FR 2019, 'Determining broad scale associations between air pollutants and urban forestry: A novel multifaceted methodological approach.', Environmental pollution (Barking, Essex : 1987), vol. 247, pp. 474-481.View/Download from: UTS OPUS or Publisher's site
Global urbanisation has resulted in population densification, which is associated with increased air pollution, mainly from anthropogenic sources. One of the systems proposed to mitigate urban air pollution is urban forestry. This study quantified the spatial associations between concentrations of CO, NO₂, SO₂, and PM₁₀ and urban forestry, whilst correcting for anthropogenic sources and sinks, thus explicitly testing the hypothesis that urban forestry is spatially associated with reduced air pollution on a city scale. A Land Use Regression (LUR) model was constructed by combining air pollutant concentrations with environmental variables, such as land cover type and use, to develop predictive models for air pollutant concentrations. Traffic density and industrial air pollutant emissions were added to the model as covariables to permit testing of the main effects after correcting for these air pollutant sources. It was found that the concentrations of all air pollutants were negatively correlated with tree canopy cover and positively correlated with dwelling density, population density and traffic count. The LUR models enabled the establishment of a statistically significant spatial relationship between urban forestry and air pollution mitigation. These findings further demonstrate the spatial relationships between urban forestry and reduced air pollution on a city-wide scale, and could be of value in developing planning policies focused on urban greening.
Irga, P, Pettit, T, Irga, R, Paull, N, Douglas, A & Torpy, F 2019, 'Does plant species selection in functional active green walls influence VOC phytoremediation efficiency?', Environmental Science and Pollution Research, vol. Volume 26,, no. 13, pp. 12851-12858.View/Download from: UTS OPUS or Publisher's site
Volatile organic compounds (VOCs) are of public concern due to their adverse health effects. Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms are not fully understood. This study assessed active botanical biofilters for their single-pass removal efficiency (SPRE) for benzene, ethyl acetate and ambient total volatile organic compounds (TVOCs), at concentrations of in situ relevance. Biofilters containing four plant species (Chlorophytum orchidastrum, Nematanthus glabra, Nephrolepis cordifolia 'duffii' and Schefflera arboricola) were compared to discern whether plant selection influenced VOC SPRE. Amongst all tested plant species, benzene SPREs were between 45.54 and 59.50%, with N. glabra the most efficient. The botanical biofilters removed 32.36-91.19% of ethyl acetate, with C. orchidastrum and S. arboricola recording significantly higher ethyl acetate SPREs than N. glabra and N. cordifolia. These findings thus indicate that plant type influences botanical biofilter VOC removal. It is proposed that ethyl acetate SPREs were dependent on hydrophilic adsorbent sites, with increasing root surface area, root diameter and root mass all associated with increasing ethyl acetate SPRE. The high benzene SPRE of N. glabra is likely due to the high wax content in its leaf cuticles. The SPREs for the relatively low levels of ambient TVOCs were consistent amongst plant species, providing no evidence to suggest that in situ TVOC removal is influenced by plant choice. Nonetheless, as inter-species differences do exist for some VOCs, botanical biofilters using a mixture of plants is proposed.
Pettit, T, Bettes, M, Chapman, AR, Hoch, LM, James, ND, Irga, PJ & Torpy, FR 2019, 'The botanical biofiltration of VOCs with active airflow: is removal efficiency related to chemical properties?', Atmospheric Environment, vol. 214.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier Ltd Botanical biofiltration using active green walls is showing increasing promise as a viable method for the filtration of volatile organic compounds (VOCs) from ambient air; however there is a high level of heterogeneity reported amongst VOC removal efficiencies, and the reasons for these observations have yet to be explained. Comparisons of removal efficiencies amongst studies is also difficult due to the use of many different VOCs, and systems that have been tested under different conditions. The current work describes a procedure to determine whether some of these differences may be related to the chemical properties of the VOCs themselves. This work used an active green wall system to test the single pass removal efficiency (SPRE) of nine different VOCs (acetone, benzene, cyclohexane, ethanol, ethyl acetate, hexane, isopentane, isopropanol and toluene) and explored which chemical properties were meaningful predictor variables of their biofiltration efficiencies. Ethanol was removed most efficiently (average SPRE of 96.34% ± 1.61), while benzene was least efficiently removed (average SPRE of 19.76% ± 2.93). Multiple stepwise linear regression was used to determine that the dipole moment and molecular mass were significant predictors of VOC SPRE, in combination accounting for 54.6% of the variability in SPREs amongst VOCs. The octanol water partition coefficient, proton affinity, Henry's law constant and vapour pressure were not significant predictors of SPRE. The most influential predictor variable was the dipole moment, alone accounting for 49.8% of the SPRE variability. The model thus allows for an estimation of VOC removal efficiency based on a VOC's chemical properties, and supports the idea that system optimisation could be achieved through methods that promote both VOC partitioning into the biofilter's aqueous phase, and substrate development to enhance adsorption.'
Pettit, T, Irga, PJ & Torpy, FR 2019, 'The in situ pilot-scale phytoremediation of airborne VOCs and particulate matter with an active green wall', Air Quality, Atmosphere and Health, pp. 33-44.View/Download from: UTS OPUS or Publisher's site
© 2019, Springer Nature B.V. Atmospheric pollutant phytoremediation technologies, such as potted plants and green walls, have been thoroughly tested in lab-scale experiments for their potential to remove air pollutants. The functional value of these technologies, however, is yet to be adequately assessed in situ, in 'high value' environments, where pollutant removal will provide the greatest occupant health benefits. Air pollution in countries such as China is a significant public health issue, and efficient air pollution control technologies are needed. This work used pilot-scale trials to test the capacity of potted plants, a passive green wall and an active green wall (AGW) to remove particulate matter (PM) and total volatile organic compounds (TVOCs) from a room in a suburban residential house in Sydney, Australia, followed by an assessment of the AGW's potential to remove these pollutants from a classroom in Beijing. In the residential room, compared to potted plants and the passive green wall, the AGW maintained TVOCs at significantly lower concentrations throughout the experimental period (average TVOC concentration 72.5% lower than the control), with a similar trend observed for PM. In the classroom, the AGW reduced the average TVOC concentration by ~ 28% over a 20-min testing period compared to levels with no green wall and a filtered HVAC system in operation. The average ambient PM concentration in the classroom with the HVAC system operating was 101.18 μg/m3, which was reduced by 42.6% by the AGW. With further empirical validation, AGWs may be implemented to efficiently clean indoor air through functional reductions in PM and TVOC concentrations.
Irga, PJ, Barker, K & Torpy, FR 2018, 'Conservation mycology in Australia and the potential role of citizen science.', Conservation biology : the journal of the Society for Conservation Biology, vol. 32, no. 5, pp. 1031-1037.View/Download from: UTS OPUS or Publisher's site
Fungi are undoubtedly important for ecosystem functioning; however, they have been omitted or given scant attention in most biodiversity policy documents, management plans, and formal conservation schedules throughout the world. This oversight may be due to a general lack of awareness in the scientific community and compounded by a scarcity of mycology-associated curricula at the tertiary level and a lack of mycologists in research institutions. Although molecular techniques advance the systematic cataloging of fungi and facilitate insights into fungal communities, the scarcity of professional mycologists in the environmental sciences hampers conservation efforts. Conversely, citizen science initiatives are making significant contributions to the mycology discipline by increasing awareness and extending the scope of fungal surveys. Future research by professional and amateur mycologists into the distribution of fungi and their function in ecosystems will help identify wider and more effective conservation goals.
Irga, PJ, Pettit, TJ & Torpy, FR 2018, 'The phytoremediation of indoor air pollution: a review on the technology development from the potted plant through to functional green wall biofilters', Reviews in Environmental Science and Bio/Technology.View/Download from: UTS OPUS or Publisher's site
Poor indoor air quality is a health problem of escalating magnitude, as communities become increasingly urbanised and people's behaviours change, lending to lives spent almost exclusively in indoor environments. The accumulation of, and continued exposure to, indoor air pollution has been shown to result in detrimental health outcomes. Particulate matter penetrating into the building, volatile organic compounds (VOCs) outgassing from synthetic materials and carbon dioxide from human respiration are the main contributors to these indoor air quality concerns. Whilst a range of physiochemical methods have been developed to remove contaminants from indoor air, all methods have high maintenance costs. Despite many years of study and substantial market demand, a well evidenced procedure for indoor air bioremediation for all applications is yet to be developed. This review presents the main aspects of using horticultural biotechnological tools for improving indoor air quality, and explores the history of the technology, from the humble potted plant through to active botanical biofiltration. Regarding the procedure of air purification by potted plants, many researchers and decades of work have confirmed that the plants remove CO2 through photosynthesis, degrade VOCs through the metabolic action of rhizospheric microbes, and can sequester particulate matter through a range of physical mechanisms. These benefits notwithstanding, there are practical barriers reducing the value of potted plants as standalone air cleaning devices. Recent technological advancements have led to the development of active botanical biofilters, or functional green walls, which are becoming increasingly efficient and have the potential for the functional mitigation of indoor air pollutant concentrations.
Paull, N, Irga, PJ & Torpy, FR 2018, 'Active green wall plant health tolerance to diesel smoke exposure', Environmental Pollution, vol. 240, pp. 448-456.View/Download from: UTS OPUS or Publisher's site
Poor air quality is an emerging world-wide problem, with most urban air pollutants arising from vehicular emissions. As such, localized high pollution environments, such as traffic tunnels pose a significant health risk. Phytoremediation, including the use of active (ventilated) green walls or botanical biofilters, is gaining recognition as a potentially effective method for air pollution control. Research to date has tested the capacity of these systems to remove low levels of pollutants from indoor environments. If botanical biofilters are to be used in highly polluted environments, the plants used in these systems must be resilient, however, this idea has received minimal research. Thus, testing was conducted to assess the hardiness of the vegetated component of a botanical biofilter to simulated street level air pollutant exposure. A range of morphological, physiological, and biochemical tests were conducted on 8 common green wall plant species prior to and post 5-week exposure to highly concentrated diesel fuel combustion effluent; as a pilot study to investigate viability in in situ conditions. The results indicated that species within the fig family were the most tolerant species of those assessed. It is likely that species within the fig family can withstand enhanced air pollutant conditions, potentially a result of its leaf morphology and physiology. Other species tested were all moderately tolerant to the pollution treatment. We conclude that most common green wall plant species have the capacity to withstand high pollutant environments, however, extended experimentation is needed to rule out potential long term effects along with potential decreases in filter efficiency from accumulative effects on the substrate.
Pettit, T, Irga, PJ & Torpy, FR 2018, 'Functional green wall development for increasing air pollutant phytoremediation: Substrate development with coconut coir and activated carbon.', Journal of hazardous materials, vol. 360, pp. 594-603.View/Download from: UTS OPUS or Publisher's site
Functional green walls are gaining attention due to their air cleaning abilities, however the air cleaning capacity of these systems may be improved through substrate modification. This experiment investigated the capacity of several green wall media to filter a range of air pollutants. Media, consisting of differently sized coconut husk-based substrates, and with different ratios of activated carbon were evaluated through the use of scaled down model 'cassettes'. Tests were conducted assessing each substrate's ability to filter particulate matter, benzene, ethyl acetate and ambient total VOCs. While the particle size of coconut husk did not influence removal efficiency, the addition of activated carbon to coconut husk media improved the removal efficiency for all gaseous pollutants. Activated carbon as a medium component, however, inhibited the removal efficiency of particulate matter. Once the substrate concentration of activated carbon approached ∼50%, its gas remediation capacity became asymptotic, suggesting that a 50:50 composite medium provided the best VOC removal. In full-scale botanical biofilter modules, activated carbon-based substrates increased benzene removal, yet decreased particulate matter removal despite the addition of plants. The findings suggest that medium design should be target pollutant dependent, while further work is needed to establish plant viability in activated carbon-based media.
Indoor air quality has become a growing concern due to the increasing proportion of time people spend indoors, combined with reduced building ventilation rates resulting from an increasing awareness of building energy use. It has been well established that potted-plants can help to phytoremediate a diverse range of indoor air pollutants. In particular, a substantial body of literature has demonstrated the ability of the potted-plant system to remove volatile organic compounds (VOCs) from indoor air. These findings have largely originated from laboratory scale chamber experiments, with several studies drawing different conclusions regarding the primary VOC removal mechanism, and removal efficiencies. Advancements in indoor air phytoremediation technology, notably active botanical biofilters, can more effectively reduce the concentrations of multiple indoor air pollutants through the action of active airflow through a plant growing medium, along with vertically aligned plants which achieve a high leaf area density per unit of floor space. Despite variable system designs, systems available have clear potential to assist or replace existing mechanical ventilation systems for indoor air pollutant removal. Further research is needed to develop, test and confirm their effectiveness and safety before they can be functionally integrated in the broader built environment. The current article reviews the current state of active air phytoremediation technology, discusses the available botanical biofiltration systems, and identifies areas in need of development.
Torpy, FR, Clements, N, Pollinger, N, Dengel, A, Mulvihill, I, He, C & Irga, PJ 2018, 'Testing the single-pass VOC removal efficiency of an active green wall using methyl ethyl ketone (MEK)', Air Quality, Atmosphere and Health, vol. 11, no. 2, pp. 163-170.View/Download from: UTS OPUS or Publisher's site
In recent years, research into the efficacy of indoor air biofiltration mechanisms, notably living green walls, has become more prevalent. Whilst green walls are often utilised within the built environment for their biophilic effects, there is little evidence demonstrating the efficacy of active green wall biofiltration for the removal of volatile organic compounds (VOCs) at concentrations found within an interior environment. The current work describes a novel approach to quantifying the VOC removal effectiveness by an active living green wall, which uses a mechanical system to force air through the substrate and plant foliage. After developing a single-pass efficiency protocol to understand the immediate effects of the system, the active green wall was installed into a 30-m3 chamber representative of a single room and presented with the contaminant 2-butanone (methyl ethyl ketone; MEK), a VOC commonly found in interior environments through its use in textile and plastic manufacture. Chamber inlet levels of MEK remained steady at 33.91 ± 0.541 ppbv. Utilising a forced-air system to draw the contaminated air through a green wall based on a soil-less growing medium containing activated carbon, the combined effects of substrate media and botanical component within the biofiltration system showed statistically significant VOC reduction, averaging 57% single-pass removal efficiency over multiple test procedures. These results indicate a high level of VOC removal efficiency for the active green wall biofilter tested and provide evidence that active biofiltration may aid in reducing exposure to VOCs in the indoor environment.
Torpy, FR, Pettit, T & Irga, P 2018, 'Applied horticultural biotechnology for the mitigation of indoor air pollution', Journal of People, Plants, and Environment, vol. 21, no. 6, pp. 445-460.View/Download from: UTS OPUS
Exposure to indoor air pollution is an emerging world-wide problem, with growing evidence that it is a major cause of morbidity worldwide. Whilst most indoor air pollutants are of outdoor origin, these combine with a range of indoor sourced pollutants that may lead to high pollutant levels indoors. The pollutants of greatest concern are volatile organic compounds (VOCs) and particulate matter (PM), both of which are associated with a range of serious health problems. Whilst current buildings usually use ventilation with outdoor air to remove these pollutants, botanical systems are gaining recognition as an effective alternative. Whilst many years research has shown that traditional potted plants and their substrates are capable of removing VOCs effectively, they are inefficient at removing PM, and are limited in their pollutant removal rates by the need for pollutants to diffuse to the active pollutant removal components of these systems. Active botanical biofiltration, using green wall systems combined with mechanical fans to increase pollutant exposure to the plants and substrate, show greatly increased rates of pollutant removal for both VOCs, PM and also carbon dioxide (CO2). A developing body of research indicates that these systems can outperform existing technologies for indoor air pollutant removal, although further research is required before their use will become widespread. Whilst it is known that plant species selection and substrate characteristics can affect the performance of active botanical systems, optimal characteristics are yet to be identified. Once this research has been completed, it is proposed that active botanical biofiltration will provide a cheap and low energy use alternative to mechanical ventilations systems for the maintenance of indoor environmental quality.
Douglas, A, Torpy, F, Surawski, N & Irga, P 2018, 'Mapping Urban Aerosolized Fungi: Predicting Spatial and Temporal Indoor Concentrations', HUMAN ECOLOGY REVIEW, vol. 24, no. 2, pp. 81-103.View/Download from: UTS OPUS or Publisher's site
Irga, PJ, Abdo, P, Zavattaro, M & Torpy, FR 2017, 'An assessment of the potential fungal bioaerosol production from an active living wall', BUILDING AND ENVIRONMENT, vol. 111, pp. 140-146.View/Download from: UTS OPUS or Publisher's site
Irga, PJ, Braun, JT, Douglas, ANJ, Pettit, T, Fujiwara, S, Burchett, MD & Torpy, FR 2017, 'The distribution of green walls and green roofs throughout Australia: Do policy instruments influence the frequency of projects?', Urban Forestry and Urban Greening, vol. 24, pp. 164-174.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier GmbH Green roofs and green walls are gaining popularity as a means of mitigating a range of environmental impacts associated with urbanisation. Although this technology has been widely implemented in some parts of the world, uptake within Australia has been slow. This might be attributed to a range of factors, including a lack of awareness; a scarcity of urban green infrastructure policies; a lack of examples to give urban designers confidence in the technology; and perhaps also a limited number of professionals capable of installing green infrastructure systems. This paper researches the distribution of green wall and green roof projects in urban Australia, and the possible influence of local government policies and guidelines that have been designed to promote the increase of green infrastructure in Australia's cities. Differences were observed among project distributions and frequency, both within and between cities. In addition, councils that offered policy instruments and guidance tended to have more green wall and green roof projects than those which have no such policies in place. Compared to successful examples seen internationally, further policy implementation in Australia could increase the frequency of green infrastructure projects, indicating that governmental influence may play a substantial role in encouraging green infrastructure installation.
Irga, PJ, Paull, NJ, Abdo, P & Torpy, FR 2017, 'An assessment of the atmospheric particle removal efficiency of an in room botanical biofilter system', BUILDING AND ENVIRONMENT, vol. 115, pp. 281-290.View/Download from: UTS OPUS or Publisher's site
Pettit, T, Irga, PJ, Abdo, P & Torpy, FR 2017, 'Do the plants in functional green walls contribute to their ability to filter particulate matter?', Building and Environment, vol. 125, pp. 299-307.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier Ltd Indoor air quality has become a growing concern as people are spending more time indoors, combined with the construction of highly sealed buildings that promote thermal efficiency. Particulate matter (PM) is a common indoor air pollutant, with exposure to high concentrations associated with several detrimental health outcomes. Active botanical biofilters or functional green walls are becoming increasingly efficient and have the potential to mitigate high suspended PM concentrations. These systems, however, require further development before they become competitive with industry standard in-room air filters. Whilst the plant growth substrate in active biofilters can act as a filter medium, it was previously not known whether the plant component of these systems played a function in PM filtration. This study thus examines the influence of the botanical component on active green wall PM single pass removal efficiency (SPRE), with a focus on evaluating the air filtration features of different plant species in green wall modules. All tested botanical biofilters outperformed biofilters that consisted only of substrate. Green walls using different plant species had different single pass removal efficiencies, with fern species recording the highest removal efficiencies across all measured particle sizes (Nephrolepis exaltata bostoniensis SPRE for PM 0.3-0.5 and PM 5-10 = 45.78% and 92.46% respectively). Higher removal efficiencies were associated with increased pressure drop across the biofilter. An assessment of plant morphological data suggested that the root structure of the plants strongly influenced removal efficiency. These findings demonstrate the potential to enhance active botanical biofiltration technology with appropriate plant species selection.
Torpy, F, Zavattaro, M & Irga, P 2017, 'Green wall technology for the phytoremediation of indoor air: a system for the reduction of high CO2 concentrations', Air Quality, Atmosphere and Health, vol. 10, no. 5, pp. 575-585.View/Download from: UTS OPUS or Publisher's site
© 2016 Springer Science+Business Media DordrechtAlong with the growing requirement to reduce building carbon emissions, a need has arisen to find energy efficient means of improving the quality of indoor air. Indoor plants have been shown to be capable of reducing most air pollutants; however, practical numbers of potted plants will not have the capacity to control many forms of air pollution, especially CO2. Green walls are space-efficient means of increasing the density of indoor plants. We assessed an active green wall for its potential to reduce CO2 in chambers and a test room. Chlorophytum comosum and Epipremnum aureum were both effective cultivars for CO2 removal at light densities greater than 50 μmol m−2 s−1. Substrate ventilation increased the rate of CO2 draw down from chambers, possibly due to increased leaf gas exchange rates. Green walls were then tested in a 15.65-m3 sealed simulation room, allowing the calculation of clean air delivery rate (CADR) and air changes per hour (ACH) equivalents based on CO2 draw down. Rates of CO2 draw down were modest under typical brightly lit indoor conditions (50 μmol m−2 s−1); however, when light intensity was increased to relatively bright levels, similar to indoor conditions next to a window or with the addition of supplementary lighting (250 μmol m−2 s−1), a 1-m2 green wall was capable of significant quantifiable reductions of high CO2 concentrations within a sealed room environment. Extrapolating these findings indicates that a 5-m2 green wall containing C. comosum could balance the respiratory emissions of a full-time occupant.
Irga, PJ & Torpy, FR 2016, 'A survey of the aeromycota of Sydney and its correspondence with environmental conditions: grass as a component of urban forestry could be a major determinant', Aerobiologia, vol. 32, pp. 171-185.View/Download from: UTS OPUS or Publisher's site
© 2015 Springer Science+Business Media Dordrecht A comprehensive survey of airborne fungi has been lacking for the Sydney region. This study determined the diversity and abundance of outdoor airborne fungal concentrations in urban Sydney. Monthly air samples were taken from 11 sites in central Sydney, and culturable fungi identified and quantified. The genus Cladosporium was the most frequently isolated fungal genus, with a frequency of 78 % and a mean density of 335 CFU m−3. The next most frequently encountered genus was Alternaria, occurring in 53 % of samples with a mean of 124 CFU m−3. Other frequently identified fungi, in decreasing occurrence, were as follows: Penicillium, Fusarium, Epicoccum, Phoma, Acremonium and Aureobasidium. Additionally, seasonal and spatial trends of airborne fungi were assessed, with increases in total culturable fungal concentrations experienced in the summer months. The correspondence between a range of key environmental variables and the phenology of airborne fungal propagules was also examined, with temperature, wind speed and proximal greenspace having the largest influence on fungal propagule density. If the greenspace was comprised of grass, stronger associations with fungal behaviour were observed.
Irga, PJ & Torpy, FR 2016, 'Indoor air pollutants in occupational buildings in a sub-tropical climate: Comparison among ventilation types', BUILDING AND ENVIRONMENT, vol. 98, pp. 190-199.View/Download from: UTS OPUS or Publisher's site
Irga, PJ & Torpy, FR 2016, 'Indoor air pollutants in occupational buildings in a sub-tropical climate: Comparison among ventilation types', Building and Environment, vol. 100, pp. 227-227.View/Download from: UTS OPUS or Publisher's site
Irga, PJ, Armstrong, B, King, WL, Burchett, M & Torpy, FR 2016, 'Correspondence Between Urban Bird Roosts and the Presence of Aerosolised Fungal Pathogens', MYCOPATHOLOGIA, vol. 181, no. 9-10, pp. 689-699.View/Download from: UTS OPUS or Publisher's site
Irga, PJ, Burchett, MD, O Reilly, G & Torpy, FR 2016, 'Assessing the contribution of fallen autumn leaves to airborne fungi in an urban environment', Urban Ecosystems, vol. 19, no. 2, pp. 885-898.View/Download from: UTS OPUS or Publisher's site
Many street trees in urban areas are deciduous and drop leaves during autumn. These leaves are a potential growing substrate for fungi, which when aerosolized and inhaled, can lead to allergy along with more serious diseases. This investigation assessed the potential contribution of fallen leaves to the diversity of airborne fungal propagules during autumn. The senescent leaves of five deciduous tree species prevalent in urban environments were subject to a manipulative experiment in which their phyllospheric fungi were aerosolized, cultured and identified. Aerosolized fungi were compared with fungi detected from direct observation of the phyllosphere. Thirty-nine fungal genera were identified across the plant species sampled, of which twenty-eight were present in corresponding air samples. Significant differences were observed amongst the fungal genera growing on the leaves of the different trees, however few differences were found in the composition of fungal spores that were aerosolized. The dominant genera that were aerosolized were: Penicillium, Cladosporium, Alternaria, Chaetomium, Botrytis and Trichothecium. Some of these fungi are known to produce allergy and other symptoms in humans. As these fungal genera have been commonly identified in autumn air samples in other studies, it is likely that the phyllospheric fungi present on deciduating leaves contribute to the aeromycota of urban areas.
Irga, PJ, Burchett, MD & Torpy, FR 2015, 'Does urban forestry have a quantitative effect on ambient air quality in an urban environment?', ATMOSPHERIC ENVIRONMENT, vol. 120, pp. 173-181.View/Download from: UTS OPUS or Publisher's site
Torpy, FR, Irga, PJ & Burchett, M 2014, 'Profiling indoor plants for the amelioration of high CO2 concentrations', Urban Forestry & Urban Greening, vol. 13, pp. 227-233.View/Download from: UTS OPUS or Publisher's site
Research over the last three decades has shown that indoor plants can reduce most types of urban air pollutants, however there has been limited investigation of their capacity to mitigate elevated levels of CO2. This study profiled the CO2 removal potential of eight common indoor plant species, acclimatised to both indoor and glasshouse lighting levels, to develop baseline data to facilitate the development of indoor plant installations to improve indoor air quality by reducing excess CO2 concentrations. The results indicate that, with the appropriate choice of indoor plant species and a targeted increase in plant specific lighting, plantscape installations could be developed to remove a proportion of indoor CO2. Further horticultural research and development will be required to develop optimum systems for such installations, which could potentially reduce the load on ventilation systems.
Irga, PJ, Torpy, FR & Burchett, M 2013, 'Can hydroculture be used to enhance the performance of indoor plants for the removal of air pollutants?', Atmospheric Environment, vol. 77, no. 1, pp. 267-271.View/Download from: UTS OPUS or Publisher's site
The indoor plant, Syngonium podophyllum, grown in both conventional potting mix and hydroculture, was investigated for its capacity to reduce two components of indoor air pollution; volatile organic compounds (VOCs) and CO2. It was found that, with a moderate increase in indoor light intensity, this species removed significant amounts of CO2 from test chambers, removing up to 61% 2.2 of 1000 ppmv over a 40 min period. It was also found that the hydroculture growth medium facilitated increased CO2 removal over potting mix. The VOC removing potential of hydroculture plants was also demonstrated. Whilst the rate of VOC (benzene) removal was slightly lower for hydroculture-grown plants than those grown in potting mix, both removed 25 ppmv from the test chambers within 7 days. The effect of benzene on the community level physiological profiles of rhizospheric bacteria was also assessed. There was less variability in the carbon substrate utilisation profile of the bacterial community from the rhizosphere of hydroculture plants compared to potting mix, however the species present encompassed at least those involved with VOC removal. Overall, we propose that plants grown in hydroculture can simultaneously deplete CO2 and VOCs, and thus may have potential for improving indoor air quality.
Torpy, FR, Irga, PJ, Brennan, JP & Burchett, M 2013, 'Do indoor plants contribute to the aeromycota in city buildings?', Aerobiologia, vol. 29, pp. 321-331.View/Download from: UTS OPUS or Publisher's site
Do indoor plants contribute to the aeromycota in city buildings?
Torpy, FR, Irga, PJ, Moldovan, D, Tarran, J & Burchett, M 2013, 'Characterization and biostimulation of benzene biodegradation in the potting-mix of indoor plants', Journal of Applied Horticulture, vol. 15, no. 1, pp. 10-15.View/Download from: UTS OPUS
Over 900 volatile organic compounds (VOCs) have been detected in indoor air, where they cause acute and chronic health problems to building occupants. Potted-plants can signifi cantly reduce VOC levels in indoor air, the root-zone bacteria of the potting mix effecting most of the VOC biodegradation. In this study, a baseline community level physiological profi le (CLPP) was established for the potting mix bacteria of the indoor plant species, Spathiphyllum wallisii `Petite, using Biolog EcoPlates, to provide information on the functional abilities of this community. Changes in the CLPP resulting from benzene exposure were then determined and following the identifi cation of the carbon sources associated with changes in the CLPP, biostimulant solutions were formulated and applied to fresh potted-plant specimens. Biostimulation of benzene removal was observed, with increases in removal rates of about 15%, providing proof-of-concept for the biostimulation of this process. The findings further elucidate the mechanisms of bacterial activity associated with removal of indoor airborne benzene, and could be applied to increase VOC biodegradation rates, augmenting the uses of indoor plants in improving building environmental quality.
Torpy, FR, Burchett, M & Irga, P 2015, 'Chapter 8: Reducing indoor air pollutants through biotechnology.' in Torgal, FP, Labrincha, JA, Diamanti, MV, Yu, C-P & Lee, HK (eds), Biotechnologies and Biomimetics for Civil Engineering, Springer, Switzerland, pp. 181-210.View/Download from: UTS OPUS or Publisher's site
Putting forward an innovative approach to solving current technological problems faced by human society, this book encompasses a holistic way of perceiving the potential of natural systems.
Irga, PJ & Torpy, FR 2017, 'Can urban forestry really reduce air pollution? A field study on a city scale.', Green Infrastructure: Nature Based Solutions for Sustainable and Resilient Cities, Orvieto, Italy.View/Download from: UTS OPUS
Paull, NJ, Irga, PJ & Torpy, FR 2017, 'Active green wall technology for the phytoremediation of indoor air pollutants', Green Infrastructure: Nature Based Solutions for Sustainable and Resilient Cities.View/Download from: UTS OPUS
Abdo, P, Huynh, BP, Avakian, V, Nguyen, TT, Gammon, J, Torpy, FR & Irga, PJ 2016, 'Measurement of air flow through a green-wall module', Proceedings of the 20th Australasian Fluid Mechanics Conference, Australasian Fluid Mechanics Conference, Australasian Fluid Mechanics Society, Perth.View/Download from: UTS OPUS
Irga, PJ & Torpy, FR 2016, 'A survey of aeromycota for urban Sydney and their relationships with environmental parameters', Australasian Mycological Society & Fungal Network of New Zealand Joint Meeting Conference, Queenstown, New Zealand..View/Download from: UTS OPUS
KEY RESEARCH HIGHLIGHTS
Operational parameters of the Junglefy Breathing Wall system were determined and characterised. Data collected included system water loss, pressure drop, air distribution and the system's effect on ambient temperature and relative humidity.
Clean air delivery rates were calculated utilising the removal efficiencies. The system produced 25.86¬–28.70 m3/h per module, depending on particle size and airflow rate. A typical Breathing Wall of 10 m2, utilising 40 modules would thus produce up to 12,700 m3/h of particle-free air.
Tests were conducted to identify the most appropriate plant species for survival in high pollution environments. All of the plant species tested, which are currently used in commercial applications of the Breathing Wall, recorded moderate air pollutant tolerance, and thus the system using the current plant species could possibly be used in industrial applications. Pollutant effect on air filled porosity of the substrate was negligible, even under extremely high pollutant loads.
Air quality tests were conducted at the Lend Lease Head Office, and the efficiency of the first Breathing Wall installation was monitored. The Breathing Wall is successfully reducing ambient particulate matter and carbon dioxide relative to outdoors and other areas throughout the building. Additionally, air pollutants including carbon monoxide, volatile organic compounds and sulphur dioxide were below the detection limit of the equipment being used, indicating excellent indoor environmental quality. The results indicate that the Breathing Wall is working as intended.
City of Sydney
Parramatta City Council
Randwick City Council
Transport for NSW
Lend Lease Pty Ltd
Interior Plantscape Association
Horticultre Australia Ltd
Junglefy Pty Ltd