Portable sensor lets users monitor air pollution on their smartphone
By Ben Coxworth
December 19, 2012
Air quality is one of those things that many of us should be more concerned about, but aren’t. According to some people, this is because we’re not easily able to know how clean the air around us really is – we just assume it’s “clean enough.” Computer scientists at the University of California, San Diego have set out to change that. They’re developing a compact, portable air pollution sensor that communicates with the user’s smartphone, to provide real-time air quality readings for their immediate surroundings.
Known as CitiSense, the device is able to measure local concentrations of ozone, nitrogen dioxide and carbon monoxide, which are the pollutants emitted most by internal combustion vehicles. That data is wirelessly transmitted to the user’s smartphone, where it’s displayed on the screen via a custom app – along with an actual number rating, the display also utilizes the EPA’s color code scale, where green is good and purple ... isn’t.
One of the ideas behind the sensors is that if commercialized, they would allow everyday people to be more proactive when it comes to air pollution. Users could avoid areas where the levels are dangerously high, for example, and would perhaps be more motivated to pressure local authorities to do something about the problem.
Also, data gathered from a multitude of the sensors throughout a region could provide the public with much more detailed and accurate air quality reports than is currently possible. According to the university, although San Diego County measures approximately 4,000 square miles (10,360 sq km), it is currently served by only about ten air-quality monitoring stations.
To test the technology, 30 people were given prototype CitiSense sensors to use in their everyday lives for a period of four weeks. Among other things, the test subjects discovered that air pollution is worse in particular highly-localized areas – it’s not just evenly diluted throughout the air. Not surprisingly, it was likewise noted that certain times of day are more hazardous than others.
Unfortunately for those of us who do our part to reduce pollution, it was also found that people who cycled or waited for the bus along a given route were exposed to more airborne pollutants than those who drove the same route.
The sensors presently cost US$1,000 per unit to build, but the researchers are confident that the price could be greatly reduced by mass production – they could conceivably even be incorporated into commercial smartphones. Although the constant data exchange between the prototype sensors and their paired phones is a considerable drain on the phones’ batteries, that could reportedly be addressed by limiting such exchanges to spaced intervals, or only when requested by the user.
North Carolina-based tech firm RTI International is developing a somewhat similar gadget known as the MicroPEM (Personal Exposure Monitoring device), although it doesn’t provide real-time readings. The University of Southern California has also created an Android app that uses the phone’s camera to measure particulate matter in the atmosphere, but it doesn't determine what those particles consist of.