The Unmask My City campaign launched on May 2nd—World Asthma Day—in ten cities around the world. A partnership of the Global Climate and Health Alliance, the US Climate and Health Alliance, Utah Physicians for a Healthy Environment and many others, the campaign uses LED-equipped face masks that allow people to see whether the air around them is polluted with high levels of dangerous particulate matter. The data and images produced from the campaign will be used to raise awareness about air pollution’s threat to human health and our climate. Salt Lake City represents the US in the global campaign, but it is hardly the only US city with serious air pollution problems. According to the American Lung Association’s annual State of the Air Report, 125 million Americans are exposed to unhealthy levels of ozone and particle pollution, resulting in 200,000 premature deaths each year. More than 24 million Americans suffer from asthma, which can be caused or exacerbated by air pollution. While the report notes that 2017 marks a continuation in air quality improvement across the nation, these gains are far from enough.