OUR OVERARCHING OBJECTIVE IS TO INCREASE THE VALUE OF NASA EARTH SCIENCE PRODUCTS FOR MONITORING FINE PARTICULATE MATTER (PM2.5) NEAR THE EARTH'S SURFACE. SATELLITE AEROSOL OPTICAL DEPTH (AOD) IS A MEASURE OF THE INTEGRATED AEROSOL LOADING THROUGH THE ENTIRE COLUMN. SURFACE PM2.5 CAN BE PREDICTED FROM SATELLITE AOD BY USING DATA FROM FIXED GROUND MONITORS AND ADDITIONAL APRIORI ASSUMPTIONS. HOWEVER FIXED MONITORS THAT PROVIDE HIGH-QUALITY DATA ARE SPATIALLY SPARSE. AS A RESULT SATELLITE-DERIVED SURFACE PM2.5 IS HIGHLY UNCERTAIN DUE TO SPARSE POINT MEASUREMENTS AS WELL AS UNCERTAINTIES IN AOD/PM2.5 RELATIONSHIPS FOR DIFFERENT REGIONS. TO ADDRESS THESE CHALLENGES WE PROPOSE TO COLLECT SPATIALLY DENSE QUALITY PM2.5 DATA USING LOW-COST SENSORS DEPLOYED BY CITIZEN SCIENTISTS IN THREE DIFFERENT REGIONS REPRESENTING LOW (RALEIGH) MODERATE (LOS ANGELES NC) AND HIGH (DELHI INDIA) PM2.5 LOADINGS. THE SURFACE PM2.5 GRADIENTS FROM SENSOR DATA CAN BE USED TO VALIDATE GRADIENTS IN SATELLITE-DERIVED PM2.5; THUS HELP FINE-TUNE REGION-SPECIFIC INTERPRETATION OF SATELLITE DATA FOR PM2.5 MONITORING. BY LEVERAGING LOCAL CITIZEN SCIENTISTS SUCH EFFORTS CAN BE COST-EFFECTIVE AND SUSTAINABLE WHILE ALSO ENHANCING NASA'S MISSION.THE WORK WILL BE CONDUCTED IN TWO PHASES: PROTOTYPE PHASE AND IMPLEMENTATION PHASE. THE PROTOTYPE PHASE WILL TEST AND SELECT SENSORS SUITABLE FOR USE IN THE THREE REGIONS PERFORM PROTOTYPE FIELD DEPLOYMENT IN LOS ANGELES DEVELOP STANDARD PROTOCOLS FOR USE BY CITIZEN SCIENTISTS; AND DESIGN DATA FRAMEWORK CONCEPT. WE WILL DEPLOY THIS FRAMEWORK ON A LARGER SCALE IN THE THREE REGIONS DURING IMPLEMENTATION PHASE. DATA WILL CONTINUALLY FEED TO AN OPEN-SOURCE WEB PORTAL FOR VISUALIZATION DATA ARCHIVAL AND ANALYSIS. BY COMBINING GROUND (SENSORS FIXED MONITORS AERONET) SATELLITES (MODIS AND MAIAC AOD CALIPSO) AND REGIONAL AIR QUALITY MODEL (CMAQ) DATA WE WILL EXAMINE AOD/PM2.5 RELATIONSHIP FOR EACH REGION AND ASSESS THE IMPACT OF SPATIAL RESOLUTION ON SATELLITE ESTIMATED PM2.5.OUR FRAMEWORK INCLUDES WAYS TO RECRUIT TRAIN AND MOTIVATE CITIZEN SCIENTISTS THROUGH WORKSHOPS TO INTERACT AND RECEIVE HANDS-ON TRAINING ON SENSORS AND SATELLITE DATA TOOLS AND APPLICATIONS. SUCH ACTIVITIES MOTIVATE THEM TO UNDERSTAND THEIR ENVIRONMENT BY APPLYING THESE TOOLS WHICH IS A CRUCIAL FACTOR FOR LONG-TERM SUSTAINABILITY. UPON PROJECT COMPLETION WE PROPOSE TO INVOLVE LOCAL REGULATORY OR CITIZEN SCIENCE GROUPS TO CONTINUE THE PROGRAM USING THE ESTABLISHED FRAMEWORK FOR SUSTAINABILITY OF THE PROJECT. OUR FLEXIBLE OPEN SOURCE FRAMEWORK WITH STANDARDIZED PROTOCOLS MAKE THIS POSSIBLE.OUR TEAM INCLUDES EXPERTS FROM NINE DIFFERENT INSTITUTIONS WITH EXPERTISE IN AIR QUALITY MEASUREMENTS MODELING SENSOR DEPLOYMENT SATELLITE DATA QUALITY ASSURANCE CITIZEN/COMMUNITY OUTREACH AND OPEN DATA PORTAL THEREBY ASSURING SUCCESSFUL EXECUTION OF THE PROPOSED PROJECT.THE PROPOSED DENSE SENSOR NETWORK WILL HELP EVALUATE EXISTING NASA'S AEROSOL PRODUCTS AT 3 AND 10-KM SPATIAL RESOLUTIONS AS WELL AS MAIAC 1-KM AEROSOL PRODUCT. THE IMPROVED SCIENTIFIC UNDERSTANDING FROM THIS PROJECT WILL IMPROVE THE VALUE OF AIR QUALITY DATA SETS FROM NASA'S CURRENT (MODIS VIIRS) AND FUTURE (TEMPO GEO-CAPE) MISSIONS AS WELL AS OTHER MISSIONS (NOAA'S GOES-R; KOREAN GEMS; EUROPEAN SENTINAL-4).