NASA’s Earth Observatory has this map of aerosols in Earth’s atmosphere, based on MODIS data from August 2010. “Dust storms, volcanic eruptions, wildfires, and salt spray from the winds over the ocean are the most common and abundant producers of aerosols. Humans generate them, too, through the burning of fossil fuels, manufacturing processes, and fires for cooking, heating, and agricultural clearing. … Yellow areas are predominantly coarse particles, like dust and sea salt, while red areas are mainly fine aerosols from smoke or pollution. Gray indicates areas with no data. The brighter or more intense the color, the higher the concentration of aerosols.”
Previously: Mapping Global Fine-Particulate Matter Levels.