Estimating Exposure t

Residential Woodsmoke 

Rochester, NY

Philip K. Hopke

Institute for a Sustainable Environme

Clarkson University
OUTLINE

• Exposure Assessment• Rochester Results – General Exposure – Local Exposure• Summary/Conclusions
Exposure Assessment

• Exposure is the amount of time peo

are in contact with specific concentrations of woodsmoke or otbiomass burning particles.

• We want to separate the woodsmok

component from other sources of Pbased on the measured chemical constituents. 
Receptor Models

• Receptor models use the diff

patterns of composition that different sources emit to sepathe measured particle compositions into how much the material comes from each source.
Measurements in Rochest

• Fixed site measurements at N

DEC site

–Particle compositions every th

day 

–Light absorption at 2 wavelen

(370 and 880 nm)
Rochester, 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 21.8 oC, and Feb of -4.7 oC

• Prevailing wind direction southwesterly

Buses: 17%HDDV: 8%
Black Carbon and Delta-

• The two-wavelength aethalom

measures the optical absorptioPM at 880 nm (BC) and 370 n(UVBC). 

• Organic aerosol components o

wood combustion PM enhancoptical absorption at 370 nm relative to 880 nm.
Black Carbon and Delta-

• The difference in the amount o

black carbon measured at 880 and 370 nm is defined to be D

C. 

• Prior work has suggested that 

C provides a good indicator of biomass burning.
Black Carbon and Delta-

• A definitive indicator of biom

burning is levoglucosan, a sugproduced by the decompositiocellulose.
Delta-C and Levoglucosan

Linear regression analysis results between Delta-C 

levoglucosan during spring, summer, fall, and win
Results

Figure 1. Time series plot of the monthly average Delta-C values (gray 

ambient temperature (solid circles). The correlation coefficient

between the two variables is shown in the top-right corner.
Results (cont.)

Figure 5. The scatter plot of hourly Delta-C versus PM2.5 concentra

during winter. The edge is shown by the black solid line. 
Source Apportionment in Roch

• An edge with PM2.5 to Delta-

ratio of 7.5 was observed. ThRochester RWC contribution winter PM2.5 can, therefore, b

estimated to be 17%.

• Similar results were obtained 

from the composition data.
Source Apportionment in Roch
• The annual average contribut

of woodsmoke to PM2.5 concentrations was ~7%.

Source Apportionment in Roch

Wang et al., Atm Env 2012 Wang et al., JAWMA 20

Soil 1.02 Soil 

Wood combustion 0.72 Wood combustion Diesel emissions 0.62 Diesel emissions Gasoline vehicles 0.63 Gasoline vehicles Secondary nitrate 0.50 Secondary nitrate Secondary sulfate 3.62 Secondary sulfate Isoprene SOA 0.55 Road salt Other SOA 0.29
Source Apportionment in Roch

• However, the amount of 

woodsmoke contributions are quite seasonal in nature. 30% of 

winter PM2.5
Mobile Measurements in Roch

• Mobile measurements around 

east side of Rochester

–Particle size distributions–Light absorption at 2 wavelen



LOCAL SCALE EXPOSUR

• Peak PM concentrations of 

biomass smoke reached ~6 

μ

in the vicinity of a source are

• There is also an increase in 

particles in size ranges that aeffectively deposited in the conducting airways.
LOCAL SCALE EXPOSUR

• Thus, local exposure to biom

smoke such as would occur ivicinity of a source area coulhigher than that experienced the general population. 
CONCLUSIONS

• Woodsmoke in winter repres

significant source of PM2.5 aultrafine particles

• Local exposures can be 

significantly higher than thosacross the community.
Thanks for your attention

QUESTIONS?