Air Quality Impacts of the Bulkley Valley and Lakes District Woodstove Exchange Program Hind Sbihi, Phd University of British Columbia
Air quality impacts of the Bulkley Valley and Lakes District woodstove exchange program Hind Sbihi, PhD University of British Columbia
14th Annual Air Quality and Health Workshop – Vancouver, March 15th 2017 It takes a village to make …an exchange
In the beginning – Pre-exchange Then later – Post-exchange • Ryan Allen, SFU • Weiran Yuchi, BC CDC • Michael Brauer, UBC • Angela Yao, BC CDC • Sarah Henderson, BC CDC • Kris Hong, BC CDC • Gail Millar, MoE • Matthew Wagstaff • Ben Weinstein, MoE • And all the research staff • Gavin King, MoE • Scott Weichenthal, Mc Gill
PM2.5 Emissions Inventory for BC, 2014
0.3
0.2
PERCENT 0.1
0 Dust from Dust from Residential ConstructionAll industrial All mobile Prescribed paved roads unpaved wood sources sources burning roads combustion Residential Wood Combustion
• Residential wood combustion (RWC) is an important source of air pollution in mid- and high-latitude climates.
• It is a relatively unregulated source that accounts for:
• 8% of total PM2.5 emissions in Canada • > 70% during winter in some communities where RWC is prevalent.
Wood Stove Exchanges in BC
• In 2007 the British Columbia Ministry of Environment initiated a wood stove exchange program in the Bulkley Valley Lakes District of the province.
• 7,200 of 11,500 homes used wood as their primary heating fuel
• 4,200 of the wood stoves were non-certified.
• Stove exchanges were encouraged through both financial incentives and municipal bylaws.
Objective
• To evaluate the air quality impacts of this stove exchange program in four communities in the district (Burns Lake, Houston, Smithers, and Telkwa).
• To describe • Temporal patterns of RWC markers • Spatial patterns • Biomarkers of cardiovascular health following indoor/outdoor monitoring
Study area
How do we meet our objective: an outlook of the various approaches
Mobile monitoring: + aethelometers targeted pollutants, spatio-temporal trends Gravimetric samples Nephelometers Measurements campaigns: Source Spatial trends, specificity apportionment (wood smoke)
PM2.5 Regulatory data: Temporal trends monitors How do we meet our objective: an outlook of the various approaches
Identify wood smoke signal PM2.5 monitors Regulatory data: Temporal trends Establishing Empirical Evidence for Woodsmoke Pollution
Routine monitoring data • No special study required • Common features of smoky days likely identifiable • Temperature, variability, diurnal patterns
Hong, K.Y., Weichenthal, S., Saraswat, A., King, G.H., Henderson, S.B. and Brauer, M., 2017. Environmental Pollution, 220, pp.797-806.
Data collection: Monitoring and Measurements
Measurements campaigns
Regulatory monitoring Measurement campaigns
• Central site monitoring: PM2.5
• between 2007 and 2013
• Winter time (October – April)
• 91 two-week samples
Data Collection – Sample Analysis
• PM2.5 concentrations were determined gravimetrically
• Light absorbing carbon (LAC) was estimated from absorbance by Smoke Stain Reflectometer
• Levoglucosan was quantified by GC/MS.
• Filter samples were analyzed for metals by X-ray fluorescence prior to levoglucosan analysis.
Data Collection – Data Analysis
• Temporal patterns in median PM2.5 concentrations, levoglucosan concentrations, and levoglucosan/PM2.5 ratios.
• We also compared source contributions in 2007/08 with those in 2012/13
Data collection: Monitoring and Measurements
Mobile monitoring Measurements campaigns
Regulatory monitoring Mobile monitoring: Smithers and Telkwa
• Similar routes pre- and post-exchange
• Similar nephelometers
Photo from Millar, Gail. Characterizing residential wood smoke at the neighbourhood scale: An evaluation of five communities in British Columbia. University of Northern British Columbia, 2012. Other tools for air quality impacts
• Evaluation of cardiovascular health markers among non-smoker adults pre- and post-exchange in Smithers • Randomized cross-over study • systemic inflammation • microvascular endothelial dysfunction (RHI)
Allen RW, Carlsten C, Karlen B, Leckie S, Eeden SV, Vedal S, et al. Am J Respir Crit Care Med. 2011 May 1;183(9):1222–30. Summary of Tools and Data to evaluate the impact of the stoves exchange
Houston Burns Lake Telkwa Smithers 2008/09 2012 2008/09 2012/13 2008/9 2012/13 2008/09 2012/13 /13 PM2.5 fixed √ √ √ √ √ √ Levoglucosan fixed √ √ √ √ √ √ Metals √ √ √ √ √ √ Nephelometer fixed √ √ √ √ Nephelometer mobile √ √ √ √ Indoor PM2.5, √ √ Levoglucosan, BC RHI √ √ IL-6 √ √ CRP √ √ Wood stove exchange Results
Temporal patterns (1) Temporal patterns (2)
Exchanges from 2007/2008 to 2012/2013
9.3
8.3
6.7 6.5 5.7 /PM2.5 Ratio (%) Ratio /PM2.5 4.6 4.3 7.8 5.1 3.3 6.2 3.2 4.5 5.0 3.8 5.3 4.8
3.4 3.6 3.7 Levoglucosan
57% 70% 78% 86% 100% Cumulative percent stove exchanged
Burns Lake Houston Smithers Telkwa Source Contributions (Smithers and Telkwa)
(µg/m3 ) Mobile monitoring
• Scatter coefficient reflects nocturnal signal specific to stove use Comparison of PM2.5 hotspots in Smithers 2008 vs. 2014 Comparison of PM2.5 hotspots in Telkwa 2008 vs. 2014 Future direction - New generation of instrument
Future direction - multi-channel aethalometers Biomarkers of cardiovascular health
• Improvement in biomarkers with filtration • 9.4% (0.9–18%) increase in RHI and 32.6% (4.4–60.9%) decrease in CRP for HEPA filtration in ~2-week exposure window • No changes at the community level
2008-2009 Session 2012-2013 session Exposure Pre-exchange Post-exchange Biomarkers mean ± SD (median) mean ± SD(median) 7.5±5.3 7.8±9.4 2.1 ± 0.6 2.3 ± 0.5 Levoglucosa Indoors RHI (7.0) (4.8) (2.1) (2.4) n/PM 2.5 41.3±21.4 49.6±21.5 1.02 ± 0.8 2.0 ± 5.2 Ratio ×1000 Outdoors CRP (mg/L) (46.7) (52.1) (0.8) (0.8) Policy implication
• Was the exchange effective? • Yes: Lower contribution of RWC to air pollution • However, while per stove emissions went down total stoves went up
• Tools are available • to target communities where the upgrades are most needed/beneficial • to empirically measure the impact of upgrades • Within community to map hotspots • Tools for targeted incentives Smithers Quesnel Levoglucosan: Specific marker for Woodsmoke Pollution
• Requires special study • Fixed samplers for at least 24 hours • Expensive lab analysis
Simoneit et al (1999), Atmospheric Environment, 33(2) 442 Wood Stove Exchanged
Burns Lake Houston Telkwa Smithers Year (Population= 2,116) (Population= 3,039) (Population= 1,441) (Population= 5,347) Stoves Cumulative Stoves Cumulative Stoves Cumulative Stoves Cumulative Changed % Changed % Changed % Changed % up to end 2008 56 57% 55 50% 33 46% 92 57% 2009 13 70% 23 70% 17 70% 33 78% 2010 8 78% 16 85% 9 83% 15 87% 2011 8 86% 13 96% 5 90% 15 96% 2012 & 2013 14 100% 4 100% 7 100% 6 100% Total 99 111 71 161 Changes / 46.8 36.5 49.3 30.1 1,000 pop.