1. FASTNET Event Report: 040705July4Haze, July 6, 2004 July 4, 2004 Aerosol Pulse Event Summary by the FASTNET Community Please send PPT slides or comments to Erin Robinson or Rudy Husar, CAPITAErin Robinson Rudy Husar Visit the event discussion forum

2. Background During the US Independence day celebrations on July 4 th, fireworks cause the emission of considerable smoke in most populated areas While it is a sort-term aerosol event, the fireworks smoke has a measurable impact on the local aerosol pattern Earlier analyses of IMPROVE aerosol chemistry data have shown that fireworks smoke has a strong signature, rich in potassium (Poirot, 1998)Poirot, 1998 The FASTNET data shown here also demonstrates that the fireworks cause a strong short-term pulse of the PM2.5 concentration in most urban areas. A community analysis activity could quantify the magnitude, significance and relevance of this phenomenon.

3. Previous work: The July 4th Potassium Spike (Poirot 1998)The July 4th Potassium Spike Potassium nitrate is a major component of all fireworks (provides the bang!). Fine particle K for all IMPROVE data (1988-1997) were averaged for each day of year The potassium spike on July 5 is 120 ng/m3 compared to 40-60 during the year The corresponding IMPROVE-average daily fine mass did not show the spike The K spike is clearly something to consider (and perhaps screen out) in conducting any analyses using K data

4. FASTNET Analysis: AIRNOW PM25 Hourly data Hourly PM25 concentrations are averaged over all the AIRNOW sites (~300) Late on July 4 and early July 5, the average PM2.5 increased from 12 to 35 ug/m3 An aerosol pulse of the same magnitude occurred on July 4, 2003 Thus, the July 4-5 smoke pulse is clearly discernable in the mass concentration data

5. AIRNOW PM25 Maps, July 4, 5, 2004 12:0000:00 04:0016:00 08:00 AIRNOW PM25 mass concentration shows urban hot-spots The aerosol pulse first appeared in the East and subsequently in the West See the GIF animation for the hourly patternGIF animation 20:00

6. ASOS Light Scattering Hourly ASOS scattering is averaged over all the ASOS_STI sites (~200) Conspicuous is the absence of ANY trace of the July 4 spike Note: ASOS sites are at airports; many AIRNOW sites are downtown

7. Discussion Issues Why is the PM25 mass spike so strong in AIRNOW but not in the IMPROVE data? Is the fireworks smoke significant on regional scale? How to handle the July 4 th data in the source apportionment models (UNMIX, PMF) Is the PM25 and potassium pulse useful for further tracer analysis?

8. July 4, 2004 Aerosol Pulse The US-avg. AIRNOW PM25 shows a 3 hr. spike at midnight In the (airport) ASOS the July 4 spike is conspicuously absent Thus, the US spike is due to the urban sites affected by smoke 00:00 04:00 08:00 20:00 AIRNOW PM25 US Hourly Average ASOS Bext US Hourly Average Pulse No Pulse