In addition to the dangers that a wildfire’s flames pose to people, wildlife, and property, the smoke that they billow out poses a health hazard over an even larger area. During the fires in Southern California during the fourth week of October, the air quality deteriorated to levels that the Environmental Protection Agency categorizes as “unhealthy” in many areas.
This series of images shows the spread of smoke between October 25-27, as tracked by the Ozone Monitoring Instrument on NASA’s Aura satellite. OMI measures how much the smoke particles impede light passing through the atmosphere. Places where smoke particles (aerosols) were thickest are colored pink; relatively clear air is transparent, and clouds are white. On October 25 (top), strong Santa Ana winds had driven smoke westward over the Pacific Ocean. As the Santa Ana winds relaxed later in the week, however, smoke spread northeast as far Utah and Colorado (bottom images).
NASA images courtesy Colin Seftor, Aura Science Team.