According to recent findings, subtle changes in moss leaves can signal the presence of air pollutants in the atmosphere, in particular, sulfur dioxide, all in real-time.

The findings could make way for a simple and inexpensive technique for notifying authorities of potentially dangerous changes in air quality using a sustainable, natural plant sensor.

Led by Xingcai Qin and Nongjian Tao, a team of researchers collected wild moss, exposing it to different concentrations of sulfur dioxide inside a chamber. With help from an extremely sensitive webcam, the team discovered that moss leaves would shrink, curl and change color from green to yellow when exposed to sulfur dioxide. In some cases, those changes started almost immediately — within 10 seconds — upon exposure. Yet, the moss gradually recovered once the sulfur dioxide was removed from the chamber.

As such, the team concluded that the plant, unlike traditional colorimetric sensors, is capable of regenerating its chemical sensing capacity.

The team believes that combining remote webcams or drones with moss or other plant-based sensors could result in quick, inexpensive and more precise air quality monitoring of pollutants, particularly sulfur dioxide, over vast regions.

The study is published in the ACS journal of Analytical Chemistry.