We know that air pollution surrounds city-dwellers, but what difference would it make if we could actually see it? By combining ‘digital light painting’ with air pollution sensors, researchers and artists have found a way to make the invisible visible. Their photos highlight the health risks of particulate-crowded skies in Wales, India and Ethiopia. “Air pollution is the leading global environmental risk factor,” says Professor Francis Pope, an environmental scientist at the UK’s University of Birmingham, who led the project with artist Robin Price. “By painting with light to create impactful …