While honey is perfect for making anything a little bit sweeter, that’s not the only thing honey is good for. According to a recent study, honey can serve as a sensitive pollution detector.

As it turns out, bees pick up on trace amounts of metals as they forage for pollen, which settles on leaves and flowers from the air. When producing honey, those metals can show up in tiny amounts, reflecting the quality of the air in which the bees roam.

In a survey of urban beehives around Vancouver, the hives’ honey was found to contain minute levels of lead, especially downtown and near the city’s port—a testament to honey’s ability to indicate air quality. And with urban hives growing in number and already more numerous than many people realize, tracking pollutant levels using honey may offer an inexpensive way to monitor what’s in the air all over the world.