The Tricorder Arrives

Inventive / by Emily Anthes /

Cell phones will soon be able to sense our environment and its pollutants. This new power may change the way we move through the world, but can it motivate us to change it?

Our cell phones have become portable guides to the world around us and are changing the way we move through it — towards the nearest ATM, or available taxi, or away from a restaurant that garnered bad reviews. But what if cell phones could measure the temperature and humidity or pick up unseen environmental contaminants like air pollution, UV levels, and pollen count in our immediate surroundings?

“How would it change your ideas about moving around in the world, if you could suddenly sense things you couldn’t see?” asks Eric Paulos, an assistant professor at Carnegie Mellon’s Human-Computer Interaction Institute. Paulos wants to put tiny environmental sensors in cell phones and turn phone users into roving citizen scientists who continuously sample and respond to their personal environment. This type of local and real-time environmental data would not only facilitate science and satisfy individual curiosity, it will empower people to uncover, visualize, and collectively share information about their own neighborhoods and cities. It could ultimately encourage active participation in protecting and improving those spaces.

Top: Air quality sensors were attached to taxi cabs in Accra, Ghana. Middle: Examples of the sulfur dioxide, carbon dioxide, and GPS sensors used by students in Accra. Bottom: A carbon dioxide heat map displaying data collected in one 24-period in Accra, Ghana. The red dots pinpoint locations of measurements taken by students and taxi cabs. Images courtesy Eric Paulos.

Paulos and a team of fellow researchers have already designed several sensors that detect different types of air pollution like particulate matter, carbon monoxide, ozone, and volatile organic compounds. And they plan to build more. Paulos is also developing a corresponding software interface that will allow people to see and interact with their data across a network and tap into real-time data (“Where in the city are pollen counts highest today?”), as well as long-term trends in their local environment (“Which park tends to have the lowest level of airborne particulate matter?”). Air quality data is currently collected regionally or city-wide and does not account for block-to-block variations that occur in urban spaces, as in the potential variance between a bus stop, the sidewalk in front of a textile factory, and the stoop in front of an apartment building.

Since cell phones spend a lot of time in our pockets and purses, building sensors that gather good data has proved to be a challenge, Paulos admits. “If you just automatically sample, you will get lots of bad data.” One solution he’s working on is programming the sensors to sample the air only when the phone is in use; another is incorporating the sensor into phone headsets or Bluetooth attachments, devices that are more likely to be out in the light of day. Because the sensors can also sample on command, Paulos is brainstorming ways to authenticate the data. “What if someone drives around collecting false data to drive down real estate prices in an area?” he asks.

Sensors aren’t automatically integrated into new cell phones yet, but that’s the goal. Several phone manufacturing companies have expressed interest, Paulos says, but are waiting until the technology matures to make firm commitments. In the mean time Paulos is creating a guide for tinkerers and DIY aficionados who can build their own small, cheap, and lightweight sensors using widely available electronics parts and a popular open-source electronics platform called “Arduino.” A downloadable iPhone application that displays and analyzes the data will also be available soon.

As his technology catches on, Paulos is very optimistic of how people will interact with it. “People start to get excited about measuring things they can’t see in the everyday world,” he says. And his optimism seems warranted: In 2007, he armed students in Accra, Ghana with air-quality sensors that they could hold or attach to their backpacks and placed additional sensors on local taxicabs. The sensors identified microclimates that differed from the overall city air-quality index. But what was more interesting was the way people responded to the information. Within two weeks the students started to change their daily routes to minimize their exposure to air pollutants. One of the cab drivers decided to take his car in for emissions inspection. “There’s the technical story about how you make this system function, and there’s the social side of what happens when people start to go collect this data,” Paulos says.  As citizen scientists uncover the sources and concentrations of pollution around them, Paulos will be watching to see how people “use this information, share it, and use it to start arguing for change.”

Originally published May 1, 2009

Tags data information innovation networks systems technology

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