Portable Pollution Sensors and Smart Phone Technology

Innovative sensors aid people with chronic lung conditions.

portable pollution sensor

UC San Diego computer scientists devise an innovative
portable pollution sensor that gives instantaneous
read outs to smart phones and personal computers.

Smart phones are the equivalent of cell phones on steroids, a handheld communication and computing device that has transformed the way that we stay in touch. That technology has spawned an untold number of applications (or apps) that have made it possible to extend the use of smart phones in various ways.

Portable Pollution Sensors

Computer scientists at the University of California, San Diego recently built a small fleet of portable pollution sensors that are able to monitor air quality in real time when synched with smart phones. The sensors were designed to assist people with chronic breathing problems, including asthma and emphysema sufferers, by helping them detect and avoid unsafe pollution conditions. San Diego County, where the study was conducted, has received an “F” grade for its air quality from the American Lung Association. That failing grade is based on the pollution monitoring data collected and analyzed by the association for the county.

Dubbed CitiSense, it is the very first system of its kind that provides instantaneous air quality read outs, sending that information to cell phones and personal computers immediately. Moreover, the data measures air quality wherever these devices are placed in use — that information is available to everyone, not just individuals that are equipped with the sensors.

Data Collection

The lead investigator on the CitiSense project is William Griswold, a computer science professor at the Jacobs School of Engineering at UC San Diego. Griswold explained that his team wanted to provide additional and improved data that goes beyond the EPA-mandated air quality monitoring stations that now serve the 3.1 million residents of San Diego County. Instead of relying on data from 10 stations scattered across 4,000 square miles, researchers envision that future data might some day be pulled in by at least 100 sensors covering the same area.

Portable Pollution Sensor

A portable pollution sensor strapped to a backpack for mobile air quality data collection.

Ozone (O3), nitrogen dioxyde (NO2) and carbon monoxide (CO) are the three pollutants each CitiSense sensor detects. These are also the pollutants most commonly spewed by automobiles including passenger vehicles and trucks.

On the user interface, a color-coded scale is based on the EPA’s own air quality ratings and ranges from green for good to maroon for hazardous. Thirty users were given the sensors for four weeks, a group that included Jacobs School of Engineering faculty, staff, campus students and university commuters.

User Findings

Beyond the pilot program, users learned some important details about air pollution, with at least one myth disproven. For instance, air pollution does not dispel in the atmosphere. Instead, it collects in “hot spots” that are found along main thoroughfares, at busy intersections and elsewhere. One user, associate professor Wendy Chapman, discovered that her supposedly healthful habit of sometimes riding her bicycle to work exposed her to pollutants, especially as she used a bike path that runs astride a busy state highway. However, when she drove to work, her exposure to pollution was largely mitigated as she sat enclosed within the relatively safe air quality confines of her vehicle.

Griswold noted a certain irony in what individuals such as Chapman have been attempting to do. “The people who are doing the most to reduce emissions, by biking or taking the bus, were the people who experienced the highest levels of exposure to pollutants.”

Users also learned that air pollution levels varied at different times of the day, ranging from “low” early in the morning to much higher levels at evening rush hour. Those that bike to work discovered that they could limit their exposure to air pollution by biking one block in from a busy road. Others learned that waiting for a bus can be hazardous to their health especially if they stood by an idled bus’ tail pipe.

bike path

Biking may seem like a healthful endeavor, but research has shown that
certain bike routes wind through air pollution hot spots.

Expanded Research

University researchers would like to conduct a study in San Ysidro, a community that borders Mexico in the southern part of the county. That area has the highest levels of air pollution with school-aged children at risk. Researchers hope to win a grant from the National Institutes of Health to monitor air quality and issue a report.

CitiSense is currently a limited scale project, but its researchers would like to see it widely applied. Currently, each sensor costs $1,000 with Griswold’s team completing 20 for field deployment. An artificial intelligence method known as Latent Variable Gaussian Regression was used to capture data in an uncontrolled environment, but there are some technological challenges that remain. For instance, much battery power is consumed as data is transferred from the monitoring devices to smart phones, a problem currently handled by giving users two chargers — one for the campus and the other for the home.

The UC San Diego project was funded with a $1.5 million National Science Foundation grant. Qualcomm, Inc., provided financial backing to purchase the phones that were used in the study.

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Photos courtesy of UCSD Jacobs School of Engineering and Wikipedia.