Recent PM 2.5 Events in Burlington, VT on 2/19-20/04 & 3/1/04 (by FDMS TEOM which includes Volatile PM missed by SES TEOMs) Note: Volatile Fine Mass of 15-25 ug/m3 on event days

VT FDMS TEOMs have generally shown good agreement with FRM Mass (but not on 3/1/04 FRM day, when TEOM > FRM by about 10 ug/m3). One possible interpretation could be loss of volatile Nitrate form FRM filters.

High Fine Mass in Gt. Lakes on 2/29 and then in VT on 3/1

Burlington, VT AQI > 100 was New England Max on 2/19 (& 3/1), although similar (& even higher) PM 2.5 was reported in Southern Quebec. At L’Acadie, Quebec (SE of Montreal), collocated BAM and 30 deg SES TEOM showed BAM > TEOM by 15-30 ug/m2 (data from Michel Bisson) Tom Dann observed similar differences of 15-25 ug/m3 for colo BAM & SES TEOM in Ottawa on 2/19/03

Continuous Nitrate of 15 to 20 ug/m3 observed in Toronto on 2/19 & 2/29 (data from Jeff Brook) Similarly High Nitrate of 15 to 20 ug/m3 in Chicago on 2/18/03 (data from Donna Kenski & Chris Price

Extreme Haze observed by ASOS in BTV on 2/19 & 20 and 3/1/04 (these data are not RH-adjusted - from STI & CAPITA FASTNET) Note Similar conditions all along Eastern US/Canada border.

Transport generally parallels US/Canada Border for both events (Note: low HY-SPLIT start heights employed because Mx Ht was very low for both events. Transport Plus Local Stagnation were likely contributors)

PM 2.5 from EPA AIRNOW & RH-adjusted b scat : 2/18-20/04 Note Separate areas of high PM concentration and haze in both Northeast and Southwest Border Regions on 2/19/04. What’s that about?

Bob Vet reports high concentrations of dust in deposition samples from Chicago & southern Ontario with suspected origin from Tex/Mex dust storm. Michel Bisson reports “beige/orange snow” on Mt. Tremblent, Quebec and VT has multiple reports of “brown” or “reddish-brown” snow on 2/21/04.