TY - JOUR
T1 - Analysis of a summertime pm2.5 and haze episode in the mid-atlantic region
AU - Chen, Antony L.W.
AU - Chow, Judith C.
AU - Doddridge, Bruce G.
AU - Dickerson, Russell R.
AU - Ryan, William F.
AU - Mueller, Peter K.
PY - 2003/8
Y1 - 2003/8
N2 - Observations of the mass and chemical composition of particles less than 2.5 μm in aerodynamic diameter (PM2.5), light extinction, and meteorology in the urban Baltimore-Washington corridor during July 1999 and July 2000 are presented and analyzed to study summertime haze formation in the mid-Atlantic region. The mass fraction of ammoniated sulfate (SO42−) and carbonaceous material in PM2.5 were each ∼50% for cleaner air (PM2.5 < 10 μg/m3) but changed to ∼60% and ∼20%, respectively, for more polluted air (PM2.5 > 30 μg/m3). This signifies the role of SO42− in haze formation. Comparisons of data from this study with the Interagency Monitoring of Protected Visual Environments network suggest that SO42− is more regional than carbonaceous material and originates in part from upwind source regions. The light extinction coefficient is well correlated to PM2.5 mass plus water associated with inorganic salt, leading to a mass extinction efficiency of 7.6 ± 1.7 m2/g for hydrated aerosol. The most serious haze episode occurring between July 15 and 19, 1999, was characterized by westerly transport and recirculation slowing removal of pollutants. At the peak of this episode, 1-hr PM2.5 concentration reached ∼45 μg/m3, visual range dropped to ∼5 km, and aerosol water likely contributed to ∼40% of the light extinction coefficient.
AB - Observations of the mass and chemical composition of particles less than 2.5 μm in aerodynamic diameter (PM2.5), light extinction, and meteorology in the urban Baltimore-Washington corridor during July 1999 and July 2000 are presented and analyzed to study summertime haze formation in the mid-Atlantic region. The mass fraction of ammoniated sulfate (SO42−) and carbonaceous material in PM2.5 were each ∼50% for cleaner air (PM2.5 < 10 μg/m3) but changed to ∼60% and ∼20%, respectively, for more polluted air (PM2.5 > 30 μg/m3). This signifies the role of SO42− in haze formation. Comparisons of data from this study with the Interagency Monitoring of Protected Visual Environments network suggest that SO42− is more regional than carbonaceous material and originates in part from upwind source regions. The light extinction coefficient is well correlated to PM2.5 mass plus water associated with inorganic salt, leading to a mass extinction efficiency of 7.6 ± 1.7 m2/g for hydrated aerosol. The most serious haze episode occurring between July 15 and 19, 1999, was characterized by westerly transport and recirculation slowing removal of pollutants. At the peak of this episode, 1-hr PM2.5 concentration reached ∼45 μg/m3, visual range dropped to ∼5 km, and aerosol water likely contributed to ∼40% of the light extinction coefficient.
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U2 - 10.1080/10473289.2003.10466240
DO - 10.1080/10473289.2003.10466240
M3 - Article
C2 - 12943314
AN - SCOPUS:0041622876
SN - 1096-2247
VL - 53
SP - 946
EP - 956
JO - Journal of the Air and Waste Management Association
JF - Journal of the Air and Waste Management Association
IS - 8
ER -