Estimating Exposure toResidential Woodsmoke inRochester, NYPhilip K. HopkeInstitute for a Sustainable EnvironmentClarkson UniversityOUTLINE•Exposure Assessment•Rochester Results–General Exposure–Local Exposure•Summary/ConclusionsExposure Assessment•Exposure is the amount of time peopleare in contact with specificconcentrations of woodsmoke or otherbiomass burning particles.•We want to separate the woodsmokecomponent from other sources of PMbased on the measured chemicalconstituents.Receptor Models•Receptor models use the differentpatterns of composition thatdifferent sources emit to separatethe measured particlecompositions into how much ofthe material comes from eachsource.Measurements in Rochester•Fixed site measurements at NYSDEC site–Particle compositions every thirdday–Light absorption at 2 wavelengths(370 and 880 nm)6Rochester, New York•Located on the southern shore of Lake Ontario•The 3rd largest city of New York (2009 population of 207,294)•Annual average snowfall of 241 cm•Mean July temp of 21.8oC, and Feb of -4.7oC•Prevailing wind direction southwesterlyBuses: 17%HDDV: 8%Black Carbon and Delta-C•The two-wavelength aethalometermeasures the optical absorption ofPM at 880 nm (BC) and 370 nm(UVBC).•Organic aerosol components ofwood combustion PM enhanceoptical absorption at 370 nmrelative to 880 nm.Black Carbon and Delta-C•The difference in the amount ofblack carbon measured at 880 nmand 370 nm is defined to be Delta-C.•Prior work has suggested that Delta-C provides a good indicator ofbiomass burning.Black Carbon and Delta-C•A definitive indicator of biomassburning is levoglucosan, a sugarproduced by the decomposition ofcellulose.10Delta-C and LevoglucosanLinear regression analysis results between Delta-C andlevoglucosan during spring, summer, fall, and winter.11ResultsFigure 1. Time series plot of the monthly average Delta-C values(gray bars) andambient temperature (solid circles). The correlation coefficientbetween the two variables is shown in the top-right corner.12Results (cont.)Figure 5. The scatter plot of hourly Delta-C versus PM2.5concentrationsduring winter. The edge is shown by the black solid line.Source Apportionment in Rochester•An edge with PM2.5to Delta-Cratio of 7.5 was observed. TheRochester RWC contribution towinter PM2.5can, therefore, beestimated to be 17%.•Similar results were obtainedfrom the composition data.Source Apportionment in Rochester•The annual average contributionof woodsmoke to PM2.5concentrations was ~7%.Source Apportionment in RochesterWang et al., Atm Env 2012 Wang et al., JAWMA 2012Soil1.02 Soil0.45Wood combustion0.72 Wood combustion0.84Diesel emissions0.62 Diesel emissions1.45Gasoline vehicles0.63 Gasoline vehicles1.73Secondary nitrate0.50 Secondary nitrate1.00Secondary sulfate3.62 Secondary sulfate3.72Isoprene SOA0.55 Road salt0.12Other SOA0.29Source Apportionment in Rochester•However, the amount ofwoodsmoke contributions arequite seasonal in nature.30% ofwinterPM2.5Mobile Measurements in Rochester•Mobile measurements around theeast side of Rochester–Particle size distributions–Light absorption at 2 wavelengths18LOCAL SCALE EXPOSURES•Peak PM concentrations ofbiomass smoke reached ~6μg/m3in the vicinity of a source area.•There is also an increase inparticles in size ranges that areeffectively deposited in theconducting airways.LOCAL SCALE EXPOSURES•Thus, local exposure to biomasssmoke such as would occur in thevicinity of a source area could behigher than that experienced bythe general population.CONCLUSIONS•Woodsmoke in winter represent asignificant source of PM2.5 andultrafine particles•Local exposures can besignificantly higher than thoseacross the community.Thanks for your attention!QUESTIONS?