Evaluating the Use of Many Low-Cost Sensors for Monitoring NO 2 Gradients

1. Evaluating the Use of Many Low-Cost Sensors for Monitoring NO2 Gradients Presented by Timothy S. Dye, David L. Vaughn, Alison E. Ray, and Paul T. Roberts Sonoma Technology, Inc. Petaluma, CA Presented at the 2010 National Air Quality Conferences Raleigh, NC March 15-18, 2010 3836

2. Background • Development of citizen monitoring • Efforts to miniaturize and personalize air quality monitoring • Currently in the research stage • Several pilot projects • Many questions remain • Data quality • Representativeness • Usefulness (depends on application)

3. Example – CO and NO (UK) • Group • University of Cambridge (England) • Measurement • CO, NO, and NO2 • Location • Instrument • Small, low-cost sensors Source: http://www.escience.cam.ac.uk/mobiledata/

4. Example – CO and NO (UK) Source: http://www.escience.cam.ac.uk/mobiledata/

5. Example – CO and NO (UK) CO NO Source: http://www.escience.cam.ac.uk/mobiledata/

6. Example – Carbon Monoxide (San Francisco) Source: Allison Woodruff, Intel Research • Group: Intel Research • Measurements • CO, O3, NO2 • Temperature and relative humidity • Location and light • Instrument • Cell phone size • Solid-state sensors • Tested on street sweepers in San Francisco

7. Example – Carbon Monoxide (San Francisco) Existing routine CO monitoring sites in the SF Bay Area

8. Example – Carbon Monoxide (San Francisco) CO monitoring locations using street sweepers in San Francisco Source: Allison Woodruff, Intel Research

9. EPA NO2 Sensor Feasibility Study • Objective Evaluate the use of many small, low-cost NO2 sensors to measure pollutant gradients near roadways • Schedule: Now to August 2010 • Components of study 1. Sensor characterization 2. Field study 3. Data analysis

10. EPA NO2 Sensor Feasibility Study 1. Sensor characterization • Select sensor(s) • Perform simple evaluations in the laboratory • Zero and upscale response • Multi-concentration response (~4-5 concentration levels) • Repeatability • Response and recovery time • Interferences (temperature, chemical, electrical) • Estimate precision and accuracy • Determine tradeoffs between cost and quality • Evaluate over a range of environmental conditions

11. EPA NO2 Sensor Feasibility Study • Sensor characterization

12. EPA NO2 Sensor Feasibility Study • Sensor characterization – our first test

13. Citizen Now Field Study Fixed Study Site Path of Mobile Site EPA NO2 Sensor Feasibility Study • Field study • Design sampling strategy with fixed and mobile sites • Install near “anchor” or standard NO2 site • Collect surface meteorological measurements • Collect during a range of weather conditions New EPA Regulation State/Local monitor

14. EPA NO2 Sensor Feasibility Study 3. Data analysis • Analyze detailed NO2 and meteorological data • Time series analysis • Spatial analysis • Statistical analysis • Diagnose the spatial gradients in NO2 near roads

15. Why Is This Important? • Opportunity to • “Fill in the gaps” • Educate citizens • Change behavior • Engage and empower our communities • Challenges • Data quality, representativeness, data use, formats, ownership, privacy, etc. • Increase coordination (for the government)

16. Where Will We Be in 3-5 Years? Thousands of citizens—perhaps tens of thousands—monitoring and reporting air quality

17. Where Will We Be in 3-5 Years? • The “Citizen Environmental Monitoring Corps” is created to • Educate and certify citizens’ sensors • Empower citizens to make responsible air quality measurements • “Open AIRNow” provides a framework for education, collaboration, and participation between citizens and government