U.S. Air Quality

Code Orange PM2.5 in California; Homogeneous Cloud Capped Boundary Layer and Aerosols Aloft over Baltimore

Today's PM2.5 EPA Airnow animation shows Code Orange PM2.5 concentrations along the state of California, and Code Yellow in the Mid-Atlantic and Great Lakes states. A high pressure system (NOAA HPC surface analysis image, top right) across the region lead to light winds and somewhat warmer temperatures through the period which promoted a rise in fine particle pollution, with AOD values not exceeding 0.15.

Lidar observations over Baltimore show a homogeneous boundary layer extending up to 1.75 km, and cloud capped in the first 3 hours of observations. A light descending layer (from 6.5 to 4.5 km) of particle pollution was observed after 1800 UTC.