A Billboard That Acts Like 1,200 Trees - OZY | A Modern Media Company
Construction of section of Metro of Lima, Peru, 23 August 2013.


Because advertising is already an integral part of our cities. We might as well make it work for us.

By Niamh Ni Mhaoileoin

Peru’s University of Technology and Engineering (UTEC) believes that engineers can change the world. As proof, it has transformed billboards — fixtures so commonplace that most of us barely notice them — into sources of clean air and water for the local community. 

These efforts are welcome in the capital, Lima, a city that’s both on the rise and on the edge. Located in a coastal desert, Lima struggles with up 98-percent humidity but receives next to no rainfall each year, causing extreme water shortages. Some 1.9 million poor Limeños are forced to buy punitively expensive water from private, unregulated trucks, and they’re paying about 10 times what wealthier residents with better infrastructure pay for running water.

The pollution-fighting billboard cleans roughly 70,000 cubic meters of air per day, equivalent to 1,200 trees.

What’s more, the combination of a near-windless climate and rapid economic development means Lima has the worst air pollution in Latin America. It is, as described by native writer Daniel Alarcón, “a city with terrible traffic, alarming crime rates and a sky that’s gray for eight months a year.” 

Widespread construction is responsible for much of Lima’s pollution, filling the air with fine particles of dust, metal and stone that can cause respiratory disease, throat cancer and other health problems. The World Health Organization classifies air as clean if it contains fewer than 10 micrograms of fine particles per cubic meter. In Lima, the average level is 38 and, in poor districts in the north of the city, can climb as high as 58. By comparison, New York — one of the most polluted cities in the United States — has an average level of 14 micrograms. 

Amid this chaos, students and staff from UTEC have partnered with a local advertising company, FCB Mayo, to find cheap, innovative ways to improve Limeños’ quality of life. UTEC is building a new campus and didn’t want to add to the city’s pollution, and the ad agency was excited by the opportunity to “inspire and innovate” while contributing to the community.

Its air-purifying billboard uses existing technology that’s cleverly placed inside the highway sign. The mechanism relies on basic thermodynamic principles, with the billboard sucking air into a water tank, which balances internal heat and traps particles, allowing clean air to flow out the other side. Best of all, the billboard can be placed near construction zones to alleviate pollution.

Billboard at night

Highway Sign That Cleans the Air

Source UTEC

A similar billboard project, launched by UTEC in 2012, condensed atmospheric humidity to provide 100 liters (26 gallons) of drinkable water a day to Lima’s parched, poor communities. The water-rendering billboard was such a hit that it won a Cannes Lion Gold creativity prize. Version 2.0 of the billboard debuted earlier this year and uses the water to grow nearly 2,500 heads of lettuce a week. 

Just one of each type has been built so far — and both billboards promote the university’s mission to develop the ingenuity and talent of students through teaching-based practice. But the project could have a big future in Peru and beyond — starting with China, which will likely be attracted to any technology that can help in its battle against pollution.

UTEC claims that in a single week in March 49,800 people in the blocks around the construction site enjoyed 489,000 cubic meters of purified air. While quantities of purified air are difficult to measure and no official report has been published, UTEC believes that the particle scrubbing achieved by one billboard is equivalent to the work of 1,200 mature trees. 

Natural processes are generally preferable to artificial technology. After all, trees don’t just purify air; they also provide valuable ecosystem services such as soil conservation, water storage and flood protection, while enhancing urban spaces and offsetting city heat. Trees, however, need time and room to grow.

In the meantime, faced with Lima’s pollution and bursts of construction, air-purifying billboards are a good bet for offering up a breath of fresh air.

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