Highly elevated PM10 values were observed at the Dunham downwind monitor: a maximum hourly concentration of 6,500 µg per cubic meter occurred from 1:00 to 2:00 p.m., then a dramatic decline to 4.3 µg per cubic meter by 4:00 p.m. The average 24-hour PM10 concentration at this Dunham location was 276 µg per cubic meter, […]