Low-cost air pollution sensors for environmental and occupational health Kirsten Koehler, PhD Johns Hopkins School of Public Health TOM PETERS, GEB THOMAS, NIMA A - MOHAJER, CHRIS ZUIDEMA DREW GENTNER, MISTI ZAMORA, MICHELLE BELL FUNDING: NIOSH R01OH010533 EPA ACE CENTER R835871
Overview Why do we care about air pollution? What low-cost sensor exist? How can they help us? Two applications: 1. Ambient measurements and personal exposures 2. Occupational Exposures Conclusions and Future Work
Why do we care about air pollution? http://www.healthdata.org/sites/default/files/files/infographics/infographic_aaas_air-pollution_2016.pdf
Isn t pollution getting better in the US? National Air Pollution Trends (USEPA 2012). 57 Million people live in counties with poor air quality!
Is Monitoring Ambient Concentrations Sufficient? EPA routinely monitors air quality, but it is expensive, so it can only be done at a relatively small number of locations yet concentrations can vary over small scales. EPA only regulates outdoor air quality, so there is need to understand the associations between ambient and indoor pollution and health. If we are interested in preventing/controlling disease, way may need to consider indoor exposures, which can be much higher. 5
Typical Exposure Assessment (Personal or Occupational) Collect filter based sample 24 hours = 1 data point How can you apportion exposure to different microenvironments? Is there a better way? 6
Gas Sensors Alphasense Several companies have developed low-cost ($10-100) sensors for gas phase contaminants Linear response compared to reference instruments Can be subject to T, RH, P bias and interference from other trace gases.
Sharp DN Particle Sensors Low-cost sensor (~$20) 2.2 Diesel Fume Linear voltage response with particle mass concentration Response varies by particle type and size distribution requiring site-specific calibration Sharp DN Voltage (V) 2.0 1.0 0.4 Salt (5.0%) Salt (0.9%) ARD Welding Fume 0.2 10 100 1000 10000 Reference Mass Concentration (µg/m 3 ) Sousan et al. 2016 - AST
How well do the sensors work? NO2 Sensor: Atmos Env Volume 70, May 2013, Pages 186 203
Application 1: Exposure and Source Characterization 1. Develop sensor technology to better characterize spatial and temporal variability in pollution mixtures 2. Measure ambient exposures in a distributed network in Baltimore, MD 3. Measure personal exposures to pollution mixtures Consider influence of ambient pollution on personal exposures Consider contribution of transportation and other energy choices to personal exposures
Stationary Monitors Gas Sensors 4 PM Sensor 3 Custom designed boards Signal processing chip 2 A/C or solar power
Baltimore, MD Why Baltimore? Worst location in the east for ozone non-attainment Large-scale changes: Decommission two coal fired power plants ( 18) Expansion of port activities Changes in public transport? Opportunity to assess how realword changes impact air quality
Personal measurements can point to important sources and variability 13
What kind of data will we get? Two kinds of data: 1. High spatial- and temporal- resolution ambient data 3 years of hourly+ resolution data at 50+ locations Ability to see how different sources contribute to variability in pollutant concentrations 2. High temporal-resolution data on personal exposures for 100 participants. Personal exposures for multiple pollutants at high temporal resolution paired with GPS Impact of mobile sources to personal exposures Impact of modifiable factors on personal exposures
Application 2: Comprehensive Exposure Assessment in an Occupational Environment Physical and chemical hazards in the workplace, including noise, radiation, gases, and particulates are responsible for widespread illness and death. Emerging hazards from toxic metals and synthesized materials to engineered nanoparticles suggest this burden may increase. Inexpensive monitors are available/being developed for many occupational hazards. 15 15
New Paradigm for Occupational Exposure Assessment 1.Develop multi-pollutant monitors 2.Deploy monitors in a wireless monitoring network 3.Collect measurement data on a central computer 4.Use measurements to create hazard maps at high spatial- and temporal-resolution 5.Use worker positioning data to predict worker exposures
Bringing together different types of sensors
Conclusions A low-cost monitoring network has many advantages: Many hazards Small incremental cost to add additional sensors Provide high-resolution (time and space) measurements over cities, or on people Can provide exposure assessment for all workers at all times for similar cost as traditional exposure assessment There are exciting possibilities to bring together data from different types of sensors to answer important questions about public health