Our research

Abstract:

In reaction to media attention during the coronavirus lockdown, Brisbane City Council decided to
modify its fire pit regulations for a three-month trial period from June 1 to August 31, 2020. It is unclear how many backyard fires were lit for social purposes during the trial. However, following the trial period, Brisbane City Council residents are now permitted to continue using their fire pits as long as the smoke does not disturb their neighbours and the fire poses no harm to persons or property.

This study analyses the various fire pit regulations in Southeast Queensland’s local government areas, and examines potential impacts of fire pits compared to other sources of smoke from wood
combustion. The study also discusses whether the benefits of allowing backyard firepits might exceed the possible health consequences. The paper also includes recommendations on acceptance and criteria for backyard fires with broader consideration of other wood smoke  sources.

Authors: S M Ashrafur Rahman, Andrew P Martin, Samuel Wong, GM Hasan Shahriar

Theme: Biomass burning

Keywords: backyard, fire, council, health, fireplace, pits

Award nomination: Emerging Air Quality Professional Award

Presented at: Clean Air Society of Australia and New Zealand (CASANZ)’s International Clean Air and Environment Conference, September 2022

Abstract:

Fugitive emissions of odour and other pollutants from inside structures provide many challenges for monitoring, modelling and control. Capture using extraction allows treatment of these emissions before discharge up a stack. However the quantity that escapes capture is difficult to estimate and depends on ambient wind, size and orientation of openings, location of the source within the structure, and extraction air flow.

This paper presents an example assessment of effectiveness of capture inside a structure containing liquid waste. The pressure differential between inside and outside the structure was measured across openings. Fluctuations in pressure were large relative to the values being measured, so both an inclined manometer and a digital manometer were used. Wind speeds and direction was also measured on site.

Pressures typically ranged from -2 Pa to +1 Pa, but positive pressures only occurred for 1% of time. The average pressure differential was -0.73 Pa. As expected, higher negative pressures were measured across a smaller opening. Higher wind speeds coincided with larger pressure fluctuations. The ratio of opening area to enclosure area ranged from 0.002 to 0.003, within the USEPA guideline of 0.05. Average velocities across openings were calculated based on area and pressure differential, and found to be approximately 0.66 m/s inward, which meets ACGIH recommendation of 0.25 m/s. Despite there being some periods of escape, the velocity was within 0.25 m/s for 92% of time. We calculated that fugitive emissions ranged from 1 to 8% during the measurement period. The ventilation rate of 13 m3/m2h is within a recommended design criterion.

Authors: Andrew Martin

Theme: Odour assessment, management and control

Keywords: fugitive, odour, capture, pressure, monitoring

Presented at: Clean Air Society of Australia and New Zealand (CASANZ)’s International Clean Air and Environment Conference, September 2022

Human Health Risk Assessment (HHRA) models allow cancer risks and both acute and long-term health risks to be derived from air pollutant concentrations measured by monitors or predicted by dispersion models. These health impact predictions are generally much greater in specificity and detail than the conclusions that can be obtained by comparison to standard air pollutant criteria issued by governments and can be a valuable tool in considering the environmental justice implications of a given facility.

This study examines the utility of one HHRA methodology, the U.S. EPA Human Health Risk Assessment Protocol (HHRAP). It builds on a previous paper which evaluated the HARP risk assessment tool for similar purposes. HHRAP was developed by U.S. EPA to provide a means of simulating the risk caused by multi-pathway (air, soil, water, food, etc.) exposure to more than 200 air pollutants. It provides a standardized framework for risk assessments, but with significant flexibility to adapt the “default” configuration to appropriately model unique local circumstances and to account for the pollutant exposures associated with different lifestyles and food sources. It also allows adjustment of health effect response parameters, which HARP does not.

The method and results of an example study, examining the human health impacts of a metals recycling facility, are shown. The example case uses the BREEZE Risk Analyst software package, which imports dispersion modelling results, automates the U.S. EPA HHRAP calculations (and allows them to be customised), and provides quantitative cancer risk and health risk increment results in a GIS format that can easily be integrated with other GIS datasets relevant to risk assessment or environmental justice, such as population and demographic data.

Authors: Brian Holland, Andrew Martin, Tiffany Stefanescu

Theme: Air quality health effects

Keywords: risk assessment, risk, HHRAP, air dispersion modelling, environmental justice, ESRI, GIS

Presented at: Clean Air Society of Australia and New Zealand (CASANZ)’s International Clean Air and Environment Conference, September 2022

Abstract:

Since the year 2000, CSIRO’s The Air Pollution Model (TAPM) has been used to generate prognostic
meteorological data as input to air dispersion models. However, TAPM has several shortcomings when compared to observational data, such as underpredicting calm conditions, which are associated with poorer pollutant dispersion from ground level sources. As a result, while employing TAPM produced prognostic data, it is critical to assimilate weather station observational data for dispersion modelling.

The Weather Research and Forecasting (WRF) model has grown in prominence in recent years for
providing useful predictive data.

This paper presents prognostic modelling method and results using both the TAPM and the WRF
models for the northern and inner suburbs of Brisbane, Queensland. Statistical comparisons of wind roses from model produced data and measured data from neighbouring weather stations are
presented to illustrate similarities and differences of these two models with measured data.

Authors: S M Ashrafur Rahman, Andrew P Martin, Samuel Wong, GM Hasan Shahariar

Theme: Air quality dispersion modelling and assessment

Keywords: TAPM, WRF, prognostic, dispersion 

Award nomination: Emerging Air Quality Professional Award

Presented at: Clean Air Society of Australia and New Zealand (CASANZ)’s International Clean Air and Environment Conference, September 2022

Abstract:

Container fumigation is frequently undertaken for quarantine and pre-shipment purposes. The
process ensures that a commodity is free from pest and disease prior to export or import. Due to the hazardous nature of the chemicals used (such as methyl bromide and phosphine), physical air
emission controls such as carbon filtration are required to minimise air quality impacts. This may
involve locating containers in a large mechanically ventilated enclosure, which is not always
practical, particularly where large volumes of containers require storage and fumigation. 

Alternative solutions may be required at times in lieu of fumigant recapture.

This paper looks at the development of a venting management procedure for restricting the number of shipping containers being vented at any given time, based on prevailing wind conditions. Air dispersion modelling was undertaken using CALPUFF for a range of meteorological conditions (including wind speed, wind direction and stability class) and the maximum number of containers that can be vented under specific wind conditions was identified. From this information, a venting management chart was developed that could be used by the site operator (in conjunction with real-time meteorological data) to determine the number of shipping containers that can be  vented, while maintaining compliance with the relevant ambient air quality goals.

Authors: Samuel Wong

Keywords: methyl bromide, fumigation, air quality impacts, emissions management, air dispersion
modelling

Presented at: Clean Air Society of Australia and New Zealand (CASANZ)’s International Clean Air and Environment Conference, September 2022