Rooftop gardens help Mexico City’s fight against air pollution
In some cities, vegetated roofs offer a way to grow produce in dense areas. In Mexico City, the azoteas verdes — or green roofs — sprouting across this sprawling metropolis have a different goal: to freshen the air.
The botanical gardens generate oxygen to filter pollutants. And when it rains, they absorb water, Sam Jones reports in the Guardian. They also cool the floors below, which helps counter the “heat island effect,” a rise in urban temperatures blamed on lack of shade and buildings that trap heat. Beyond these practical benefits, green roofs serve as labs where youngsters learn about the importance of nature. The city invested nearly $1 million in green roofs last year and plans to spend more in 2014.
While Mexico City remains heavily car dependent, it is adopting other measures to improve air quality. Nearly 30 citywide monitoring stations gather data on pollution levels that can trigger driving bans on cars with certain license plates. The city has expanded its metro system, rolled out bike sharing, introduced cleaner buses and moved refineries to outlying areas.