Interactive Reading

Read the passage and answer the question.

Most people think of moss as a sign of neglect, something that grows on damp walls and forgotten rooftops. Yet several cities have begun installing 'moss walls' on purpose. These vertical panels of living moss can filter dust and certain pollutants from the air more efficiently than a similar area of grass. Because moss absorbs moisture directly from the air, it needs no soil and very little maintenance. Some panels even include sensors that alert workers when the moss becomes too dry. City planners hope these green walls will cool busy streets while quietly cleaning the air that pedestrians breathe.