Air pollution might be the tell-tale sign of alien civilizations.
Research has indicated that wide-spread industrial air pollution goes at least as far back as the ancient Greeks and Romans.
An A Moment of Science listener wrote to us: I keep hearing about the hidden costs of fossil fuels like coal. What exactly does it mean? What are hidden costs?
Scientists have found aerosol particles that would have dominated the Earth's pre-industrial atmosphere.
New research suggests that burning a candle may be toxic.
What's so important about having clean air and reducing air pollution? Find out on this Moment of Science.