A CASE-STUDY OF SMOKE CONCENTRATIONS FROM A SINGLE RESIDENTIALWOODHEATER IN HOBART, TASMANIA, AS MEASURED ON AN ADJACENT

PROPERTY.

John Innis1 and Ellis Cox1

1 EPA Tasmania, GPO Box 1550 Hobart TAS 7001 Australia

AbstractPopulation exposure to woodsmoke is a significant air quality issue in manyjurisdictions, including Tasmania. Ambient air stations are sited to be(hopefully) representative of exposure in the vicinity. In recent years mobileand/or dense network measurements have shown significant local PM2.5

inhomogeneity can exist on the sub-city and even sub--suburban scales,probably due to high woodheater densities or topographical andmicroclimatic circumstances. The prevalence of such hot-spots is ofimportance to fully understand and interpret data leading to dose-responsehealth studies.

EPA Tasmania receives complaints from householders regardingwoodsmoke issuing from neighbouring properties. These complaints arereferred to local government (councils) as the regulatory authority underTasmanian legislation. However, the EPA also provides support to councils toassist in resolving these complaints. This can include, in somecircumstances, targetted air monitoring programs to measure the severityand frequency of smoke impacts.

In winter 2016 the EPA, in conjunction with Glenorchy City Council,conducted a monitoring program in the north of Hobart in response to such acomplaint. A small monitoring station, reporting PM2.5 and meteorologicaldata in real-time, was deployed at the rear of the affected residence, some15 metres from the reported problem flue. Car-based ‘Travel BLANkET’smoke measurement surveys were also conducted in the surroundingstreets. Elevated episodic PM2.5 levels were seen on many nights, ofduration typically one hour, with peak levels of several hundred microgramsper cubic metre. On-site observations, both visual and photographic,identified the source as the previously identified flue. The elevated episodesappeared to be related to a re-loading of the woodheater prior to theoperator retiring for the night.

The local council were able to act on the information provided by the EPAdata record, and issued an Environmental Protection Notice preventing useof the woodheater.

Keywords: Woodsmoke; residential areas; PM2.5 measurement; regulation.

1. IntroductionSmoke from residential woodheaters is thesignificant contribution to poor ambient winter-timeair quality in Tasmania. Even in towns andcommunities where ambient PM2.5 levels may notregularly be elevated, smoke from a single heatercan locally degrade air quality. In Tasmania localgovernment ('the council') is the regulatory authorityfor domestic woodheaters. The TasmanianDistributed Atmospheric Emission Regulations(known as the DAE regulations) provides thelegislative framework for councils.

At times EPA Tasmania directly receives complaintsfrom members of the public concerning smokeemissions from a neighbouring property. These arein general referred to the appropriate council. Insome circumstances the EPA maintains an interestin the complaint and, in such cases, will oftenprovide some support for council as they deal withthe matter.

1.1 Claremont smoke complaintIn late winter 2014 EPA Tasmania and theGlenorchy City Council were both contacted by a

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resident of Claremont, in the northern suburbs ofHobart, concerning smoke coming from awoodheater on neighbouring property. Council andEPA officers independently made site visits. It wasnot possible to confirm the presence of high smokecoming from the identified property.

The EPA received a further communication from thecomplainant in winter 2015. The complainant wasreferred to the council. A `Travel BLANkET' (car-based smoke measurement system) survey in May2015 did include the complainant's street.Measured smoke levels were very low.

In winter 2016 the complainant contactedGlenorchy council once more. Discussions betweencouncil and the EPA led to the EPA deploying asmall, relocatable air station at the complainants'property in July 2016. Episodically high to very highPM2.5 levels (over 200 μg/m3) were recorded, oftenat around 10 to 11 pm at night. Further TravelBLANkET surveys and visual observationsconfirmed the smoke origin was the woodheater asoriginally identified by the complainant.

This paper describes the deployment and the dataobtained from the fixed-station deployment and theTravel BLANkET surveys. These data are alsodiscussed in the context of localised, very elevatedpopulation exposure that very likely occurs when aspecific woodheater emits excessive smoke levelsin a suburban setting.

2. Station deployment and data

The babyBLANkET station was installed at the rearof the complainant's Claremont residence,effectively outside a bedroom window, andapproximately 15-metres from the flue on theneighbouring property. Due to the slope in groundlevel the top of the (previously-extended) flue wasonly slightly above the station (Figure 1). Thestation was in operation from the 25th of July to the2nd of September 2016. PM2.5 and meteorologicaldata were reported to the EPA headquarters in real-time every 5-minutes via a 3G modem. Additionally,PM2.5 data were logged at a 6-second intervals on asingle-board computer at the station, and weremanually downloaded at regular intervals.

Overall, day-averaged PM2.5 levels recorded at theClaremont residence were not dissimilar to levelsmeasured at the Glenorchy air station (Figure 2),with no exceedences of the Australian 24-hourPM2.5 National Environmental Protection Standard(NEPM) of 25 μgm/3 during the deployment interval.However it was clear that there were intervals ofsignificantly elevated PM2.5 concentrations atClaremont when the hour-averaged times series

from these stations were compared, as shown inFigure 3.

Inspection of the 6-second PM2.5 time-series datarecorded at Claremont revealed the nature of theelevated concentrations: These were characterisedby very high (often over 500 μg/m3), very short-termepisodic increases in PM2.5. An example is shown in

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Illustration 1: View of the chimney flue onthe neighbouring property, as seen fromthe location of the deployed air station.The flue is approximately 15 metresdistance from the camera.

Illustration 2: Claremont and Glenorchyday-averaged PM2.5 concentrationsduring the deployment interval of 25 Julyto 2nd September 2016. Day-averagedconcentrations are similar.

Figure 4, from the night of the 7th-8 th of August2016. Soon after 23:00-h on the 7th of August the 6-second PM2.5 shows an interval of very high andvariable concentrations. This mostly ceases byaround 00:30-h on the 8th of August. The high andrapidly varying signal is suggestive of a nearbylocalised smoke source.

The daily-profile of the variation in hour-averagedPM2.5 percentile levels shows that the highestconcentrations most frequently occurred in the nighthours (Figure 5), typically between 9 and 11 pm.

3. Travel BLANkET surveys

Three Travel BLANkET surveys were conducted aspart of the monitoring program. These were on the5th, 25th and 31st of August 2016. The surveysencompassed the general Claremont area but withspecific attention to the locality of the specific area.The times of elevated PM2.5 seen in thebabyBLANkET record were of value in helping planthe surveys. On all three nights significant visiblesmoke was seen, at times, to be coming from thechimney on the property adjacent to the station. Onthe first two nights Travel BLANkET was able tosample the plume. On the third night the windmoved the plume to where it could not be reachedby car.

A Google Earth view of the 5th of August 2016survey is shown in Figure 6. Each spherical symbolrepresents the location of a measurement of PM2.5.PM2.5 levels are represented by symbol colour (darkblue ~10 to 20 μg/m3; green ~50 μg/m3; red 100μg/m3 and above) and also by height above localground level. The location of the flue and themonitoring station are also shown. The peak PM2.5

signal, that was identified as originating from theidentified flue, measured on this night with TravelBLANkET was just over 200 μg/m3. This was takenapproximately 35 metres from the flue, in the streetin front of the residence with the station. As noted,

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Illustration 4: Example of 6-second datafrom Claremont station, showing aninterval of very elevated and highlyvariable PM2.5 concentrations for the nightof the 7th-8th August, 2016.

Illustration 3: Example of hour-averagedPM2.5 time-series from Claremont (red) andGlenorchy (blue) air stations.

Illustration 5: Day-profile of hour-averagedPM2.5 percentiles.

the station at the residence was approximately 15metres from the flue.

On the 5th of August, shortly before the plume wasmeasured by Travel BLANkET in the street outsidethe Claremont residence, the station at the rear ofthe residence also recorded highly elevated PM2.5

concentrations. Figure 8 plots the time-series ofTravel BLANkET and the station for the evening ofthe 5th of August. Travel BLANkET, 35-metres fromthe flue, recorded a peak (instantaneous) PM2.5

level near 200 μg/m3. The babyBLANkET stationwas 15-metres from the flue, and recorded anumber of points over 200 μg/m3

, with peak PM2.5

concentrations near 600 μg/m3. As noted, visualobservations on the night confirmed the flue fromthe residence adjoining the complainant's house asthe origin of the smoke.

On each of the three survey nights, the visiblesmoke plume appeared after the lights were turnedoff in the house with the flue. It is conjectured thatthe increased emissions and more visible plumearose after the woodheater was reloaded with fuel,

and the air vent turned down prematurely, as theoccupiers retired for the evening.

4. DiscussionThe babyBLANkET station and Travel BLANkETsurvey data, together with some photographs (notshown here) and visual records were provided witha written analysis to the Glenorchy Council and theEnvironmental Health Section of the TasmanianDepartment of Health and Human Services(DHHS). The complainant also supplied informationthat they had undergone several major medicalprocedures, and were continuing to have furthertreatment. The DHHS concluded that theepisodically high PM2.5 levels recorded at theresidence would potentially be of concern to peoplewith certain medical conditions.

The council considered all these factors, and metseveral times with the owner and the occupier ofthe residence identified as the source of the smoke.The council noted this house was also equippedwith a reverse-cycle air conditioner. Consequently

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Illustration 6: Google Earth view of theTravel BLANkET measurements atClaremont, 7th-8th August 2016. PM2.5

levels are represented by symbol colour(dark blue ~ 10 to 20 μg/m3; green ~ 50μg/m3; red 100 μg/m3 and above) and alsoby height above local ground level. Thelocation of the flue and the monitoringstation are also shown.

Illustration 7: Time series of PM2.5 on theevening of the 5th of August recorded byTravel BLANkET (red) and babyBLANkET(blue). The red upward pointing arrowdenotes the time Travel BLANkET wasmeasuring the plume from the identifiedflue. The babyBLANkET station, at therear of the residence, was approximately15 metres from the flue. Travel BLANkETwas approximately 35 metres from theflue.

the council issued an Environmental ProtectionNotice stating that due to the impact on theneighbouring occupier the woodheater could not beused.

The smoke plume seen to be the cause of thelocally elevated PM2.5 concentrations was probablynot the most prominent or persistent of the manyplumes that have been noted by officers of EPATasmania in the course of winter-time smokesurveys and other work. In this case however thelocal topography and probably micro-climaticconditions meant the plume often impacted on theaffected residence. The affected resident was alsodetermined to bring the circumstances to theattention of both council and the EPA.

It is acknowledged that the first investigations bythe EPA of the original complaint, being an initialdrive-by in 2014 and a Travel BLANkET survey inmid 2015, did not reveal the severity of thesituation. It was only after the deployment of thebabyBLANkET station to the complainants'residence in late July 2016 that the scale of theimpact became clear. This is a lesson that theauthor is intending to keep in mind for the future.

In a wider context, the data reported here may givesome guidance as to the localised impacts ofsmoke plumes from other individual woodheaters. Itis sobering to note that even though a surveyinstrument such as Travel BLANKET oftenmeasures the elevated PM2.5 concentrations from asingle plume, the levels recorded along the street

may be significantly less than experienced closer tothe chimney. In many instances the chimney-to-neighbouring-house distance is less than thechimney-to-street distance.

In many instances, air monitoring stations aresensibly and deliberately sited away from localsources in an attempt to measure representativeambient conditions. There is clearly a case for alsoconducting 'peak site' monitoring to assist ingauging the range of pollutant exposures in thecommunity. Extrapolating from the work presentedhere, it is likely that 'peak sites' in winter-timeTasmania include residential backyards.

AcknowledgmentsWe acknowledge the interest, support and efforts ofthe Environmental Health Officers of the GlenorchyCity Council in this work.

ReferencesJ. Innis, A. Cunningham, B. Hyde, and E. Cox,

2015, 'babyBLANkET: A low-cost, highly-portable,real-time, smoke-monitoring station based on theDylos DC-1700 laser particle counter'. CASANZProceedings 2015 Melbourne conference, ISBN9780987455321.

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