U.S. EPA STAR grant and research programme in NZ encourages project on community-level air monitoring in Los Angeles using low-cost sensors
Air quality varies spatially across a city, and different communities are exposed to different levels of air pollution. For this reason, several initiatives are emerging in the U.S, and around the world, to address community-level air monitoring. South Coast Air Quality Management District (SC AQMD), has been granted the U.S. EPA’s STAR grant to encourage research into community-level air monitoring. Alongside this, SC AQMD are preparing to comply with Rule AB 617, which has been enacted by the state government in California to put in place community-level air monitoring by mid-2019. SC AQMD has deployed a pilot network of several hundred sensors – including 100 AQY Micro Air Quality Monitors, provided by Aeroqual.
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The Aeroqual AQY multi-sensor units performed very well and showed: minimal down-time, and low intra-model variability for all measured pollutants.AQ SPEC Evaluation Report
The project has brought together several organizations. South Coast Air Quality Management District (SC AQMD) is the air pollution agency responsible for regulating stationary sources of air pollution in the Los Angeles Basin. They have a STAR grant from the United States Environmental Protection Agency (U.S. EPA) to educate California Communities on the use and applications of low-cost monitors and deploy these sensors for public outreach.
Aeroqual is part of a multi-year government-funded research programme, led by the University of Auckland, to develop lower-cost high density air quality monitoring. The final stage of the programme was to deploy a network at scale which led Aeroqual and SC AQMD to work together on this project in Los Angeles.
Air quality varies spatially across a city, and different communities are exposed to different levels of air pollution. Most regulatory monitoring networks in the U.S. and around the world are not dense enough to address the variability of air quality and its relative impact on different communities. In recognition of this, regulators are taking the initiative. One such initiative was the U.S. EPA’s STAR grant specifically designed to encourage research into community-level air monitoring. In California the state government has enacted Rule AB 617 which mandates community-level air monitoring be put in place by mid-2019. Both initiatives are driving the work that SC AQMD is doing with communities in Los Angeles and explain their motivation for partnering with Aeroqual on this project. To achieve community-level air monitoring, SC AQMD needed lower cost monitors.
Deploying a network of regulatory monitors at the community-level would not be technically or economically feasible. But lower cost air monitors have shown variable performance, so the success of the project would depend on making the right technology selection. SC AQMD is well aware of this, having set up an evaluation centre (AQ-SPEC) to independently test manufacturer’s claims. Since 2014, AQ-SPEC has tested more than 50 devices; all results are made public online.
Based on AQ-SPEC’s independent evaluation, SC AQMD chose to use a combination of Purple Air PA-II sensors for measuring particulate matter, and Aeroqual’s AQY Micro Air Quality Monitor (beta) for measuring ozone, nitrogen dioxide and, and fine particulate matter (PM2.5). Combined, SC AQMD has been able to deploy a pilot network of several hundred sensors. Community groups were engaged to help SC AQMD and Aeroqual find installation sites – a mix of schools, private homes, and recreational facilities. Several units are installed alongside government monitoring stations as a check on network performance. The location of the Aeroqual AQY beta devices is shown below.
The AQY beta devices measure PM2.5, ozone, nitrogen dioxide, temperature, relative humidity, and dew point. Real-time data is sent over 4G cellular network to Aeroqual’s cloud severs and from there SC AQMD accesses the data through an API. In this way SC AQMD is able to view and analyze data in their preferred software package, and Aeroqual’s technicians are able to monitor the performance of the network from the operations center in Auckland, New Zealand.
Now SC AQMD’s main interest is community engagement, outreach and education, and developing a plan for implementing new upcoming rules including AB 617. By working closely with community groups, SC AQMD has been able to demonstrate a commitment to community-level air quality initiatives for the roll out of monitoring expected by mid-2019. At the same time SC AQMD is rapidly gaining expertise in how to deploy and manage a large network of low cost sensors. SC AQMD has shared some of this knowledge in a recent article they co-published with the U.S. EPA in Environmental Science and Technology. This new expertise is allowing them to undertake the complicated task of devising a plan to deliver on AB 617 commitment’s – in a way that is technical robust and meets multiple stakeholder objectives.
From a technical viewpoint, network uptime has been 87.4% (considering these are beta prototypes, this has been acceptable; we are working on improvements). Minimal drift has been observed (-0.33 ppb/month for ozone 1.9ppb/month for NO2, and -1.7ppb/month for PM2.5). The AQY beta devices co-located with government monitoring stations exhibit strong correlation:
- Ozone (O3): r2 = 0.97
- Nitorgen dioxide (NO2): r2 = 0.78
- Particulate mattter (PM2.5): r2 = 0.76
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