“Just in Time’ Science Support to Air Quality Management Tropospheric Aerosols: Science and Decisions in an International Community A NARSTO Technical Symposium on Aerosol Science Queretero, Mexico October 23-26, 2000 R. B. Husar, B. Schichtel and S. R. Falke Center for Air Pollution Impact and Trend Analysis (CAPITA) Washington University, St. Louis, MO

Background Dust storms and large forest fires are extreme aerosol events that can cause concentrations well above the ambient air quality standard. The impact of these extreme fine particle events can reach several thousand miles from their sources and they tend to cross international boundaries. Monitoring and responding to such unpredictable, episodic, ‘out-of-jurisdiction’ events is well beyond the activities of AQ management agencies. When extreme smoke, dust or haze events occur, air quality managers and the public needs ‘just in time’, science support. Such support could consist of: –monitoring the globe for such events –issue warnings to the AQ managers and to the broader scientific community –explain the status, causes and the likely evolution of the events This report illustrates a dust and smoke event, during which ‘just in time’ science support was provided to AQ managers, public and to the broader scientific community.

The 1998 Central American Smoke Event In the spring of 1998, thousands of fires were burning in in Central America as it happens every spring. However, the 1998 fires were about twice as intense as on a ‘normal’ year. SeaWiFS and other satellite images show thick smoke over southern Mexico, Guatemala and Honduras and adjacent oceans.

3D SeaWiFS May 14, 1998

Smoke Transport over North America (SeaWiFS, TOMS and Bext) On May 15 the smoke plume was swiftly transported northward along the Mississippi Valley. By May 16 the smoke plume reached Hudson Bay in Canada. The smoke was also observed at the the surface visibility stations.

Smoke Effects on Public Health and Welfare The Texas Natural Resources Office (TNRO) has carefully monitored smoke and the before the main smoke pall arrived, TNRO has issued a health alert for the coastal region on May 12, 1998, and extended it to May 18. The health complaints prompted public health researchers to quantitatively measure the respiratory effects of the persisting smoke. The fine particle concentrations in SW Texas exceeded 200  g/m 3. As the smoke pall has stretched northward reaching St. Louis on May 15, the hourly PM10 concentrations rose sharply 156  g/m 3 - evidently the largest recorded concentration over the past ten years. The TV and print media in St. Louis as well as elsewhere, reported numerous citizen complaints on poor air quality. At the St. Louis Lambert Airport a runway was closed resulting in 30% reduction in traffic flow and significant flight delays.

Surface Bext-Ozone Comparison Surface Bext maps show the north and eastward transport of smoke aerosol Regionally, the smoke does not appear to add ozone to the existing values Rather, ozone in the smoky airmass tends to be lower than over the surrounding areas

Science Support for the Smoke Event Prior to the smoke arrival: –Alerting the local agencies for the arrival of the smoke plume During the smoke event: –Informing the public through interviews in local TV and print media After the smoke event: –Aiding EPA in delineating the spatial extent of smoke (exceedance waivers for states)

The April 1998 Asian Dust Event On April 15th, 1998 an unusually intense dust storm began in the western Chinese Province of Xinjiang, just in time for the east Asian dust season.

Trans-Pacific Dust Transport Throughout the Trans- Pacific transit, the dust appeared as a yellow dye marking its own position. Over the Pacific Ocean, the dust cloud followed the path of the springtime East- Asian aerosol plume

Dust over the West Coast of North America a. GOES 10 geostationary satellite image of the dust taken on the evening of April 27. The dust cloud, marked by the brighter reflectance covers the entire northwestern US and adjacent portions of Canada. A dust stream is also seen crossing the Rocky Mountains toward the east. b. Contour map of the PM10 concentration on April 29, Note the coincidence of high PM10 and satellite reflectance over Washington c. Regional average daily PM10 concentration over the West Coast. The sharp peak on April is due to the Asian dust.

The Activities of AQ Management Agencies Based on public complaints and monitoring data, the State of Washington Department of Ecology issued a ban on open burning on April 29th. On April 29th, the ‘PM alarm’ (PM > 50 ug/m3) sounded at several continuous monitoring stations around Vancouver, BC. On April 29th, the Idaho Dep. of Env. Quality has advised that the haze may be due to the Asian dust event. California Air Resources Board explored whether the cause of the high PM10 (> 50ug/m3) could be due to prescribed burns in Oregon, Idaho, and Washington?. The US Forest Service in Idaho was also concerned about the intense haze around Salmon and Challis National Forests and the possibility of smoke impact from prescribed fires.

The Science ‘Virtual Community’ Many Air Quality management agencies have participated in creating an instant virtual community and have benefited from the information resources on the Website in making their quick decisions. On April 30, the Washington State has issued an explanation to the public that “…now seems fairly certain that the Eastern Washington air stagnation event is due mostly to Chinese dust rather than locally generated pollutants”. In the press release, the dust event website ( FarEast/) was given to the public for further information on the event. FarEast/ Evidently, the trust of the managers in the available science support arose from the multiplicity of independent observations, and from then presented weight of the evidence. During the dust event, the main science support provided by the ad hoc ‘virtual community’ consisted of informing and educating the managers and the public through the shared web resources.

Summary and Conclusions During major dust and smoke event that cover continental-scale regions, it is now possible to provide ‘just in time’ science support air quality managers and to the public consisting of: –- monitoring the globe for such events –- alerts the AQ managers and to the broader scientific community –- explanation of the status, causes and the likely evolution of the events Recent experience shows that ‘just in time' support can be performed by ad hoc communities of scientist and managers. The communication, coordination, and information sharing for the distributed virtual community can be accomplished effectively through the World Wide Web. It would be desirable to establish a more formal and robust ‘global aerosol watch’ infrastructure, so that the discovery and the response to such exceptional events is not left to chance. The time may be ripe for the establishment of a Global Aerosol Watch and Information Network.