https://archive.ph/dd5Kl https://archive.ph/dd5Kl “Almost 2%. The reduction in carbon-dioxide concentration when 60 square centimetres of plants were placed in

https://archive.ph/dd5Kl https://archive.ph/dd5Kl “Almost 2%. The reduction in carbon-dioxide concentration when 60 square centimetres of plants were placed in an office, according to one study.”