1910: Low CO2 such an effective forest fire suppressor that only three million acres (over 350 Yarnells] burned in a single weekend
http://tomnelson.blogspot.com/2013/07/1910-low-co2-such-effective-forest-fire.html
New West, Old Story – NYTimes.comAfter the Big Burn of 1910, which consumed three million acres in a weekend, the Forest Service became the fire serviceYarnell fire containment up to 45 percent; some in area can go home tonightOn Thursday, 676 firefighters continued efforts to contain the blaze, with the total acreage burned, 8,400, unchanged from late Wednesday.