Thursday, June 27, 1974, was the beginning of a smog siege in Southern California's Inland Empire.
Temperatures topped 100 degrees and stagnant air caused ozone levels in the city of Upland to become literally hazardous at .51 parts per million. It was the last recorded Stage III smog episode in the nation.
Media attention turned to the San Bernardino County Air Pollution Control District.
"We did not yet have a plan to deal with this type of emergency, let alone the media frenzy that came with it," said Mel Zeldin, who was then the meteorologist and unofficial spokesperson for the 26 staff member APCD.
In April that year the air pollution control agencies in the region devised a three-stage smog warning system that gave each county authority to halt all commercial, industrial and recreational activities (excluding emergency services, like the fire and police departments) during Stage III episodes. A Stage III episode is defined as when the ozone level remains above .50 ppm for one hour or more.
Unfortunately, no emergency action procedures yet had been developed when the June smog siege hit. For several days news reporters, area residents and local, state, and federal agencies besieged the San Bernardino agency with calls.
"Everybody wanted to know what to do," said Zeldin, now director of the South Coast Air Quality Management District's Applied Sciences and Technology Division.
That evening Gov. Ronald Reagan issued a statement urging residents to "limit all but absolutely necessary auto travel" and recommending that those who must drive do so at reduced speeds to lessen vehicle emissions.
"Carpooling and mass transit should be used whenever possible," he said.
Without an established plan, some took voluntary steps to reduce pollution. On Friday, June 28, California Portland Cement in Bloomington and Kaiser Steel in Fontana curtailed some operations and Southern Pacific Pipeline delayed truck deliveries of gasoline to local service stations.
The county garaged its fleet of vehicles; the Parks and Recreation Department closed all municipal swimming pools and moved all scheduled outdoor programs inside; and federal employees with respiratory ailments or breathing problems were told Thursday not to report to work on Friday.
Lower temperatures and increased winds gradually reduced the smog build-up and the emergency eased over the next several days.
Editor's Note: Much of the information herein is from The Sun-Telegram newspaper of San Bernardino.