Though only two lives were lost, the explosions that leveled a rocket fuel plant at Henderson, Nev. still amount to one of the most destructive accidents in the history of the space industry.

Besides injuring more than 250 people, the earthquake-force blasts left a ring of destruction eight miles wide. Within that ring, cars were flipped over, pedestrians thrown to the ground, an airliner in the sky was jolted, and a five-square-mile cloud of black, toxic smoke boiled into the sky over much of southern Nevada.As bad as the mishap was at the Pacific Engineering and Production Co. plant, it easily could have been much worse. As it was, only 25 to 35 of the plant's 85 employees were on duty at the time of the blasts, an evacuation was quickly ordered after a fire that caused the blasts got out of control, and winds carried the toxic smoke from the explosions away from populated areas.

Since the Henderson plant had a good safety record, this unhappy episode should prompt other facilities around the country that handle explosive or other dangerous substances to reappraise their safety procedures and consider holding regular evacuation drills. Good luck is no substitute for good planning.

Such reappraisals are in order not just because of what happened at Henderson but because the safety of the nation's workplaces seems to have been slipping lately.

Just ask the National Safe Workplace Institute, which reports that even though on-the-job fatalities have continued to decline in the 1980's, the annual rate of decrease has not been as great as it was in the previous decade.

Particularly at risk are workers in construction, manufacturing, mining, steel-making, and agriculture. These workers, the Institute notes, are 21 percent more likely to die now than if the trends in place at the end of the 1970's had continued.

Meanwhile, as investigators probe the blasts at Henderson, a new look also is in order at policies for stockpiling the rocket fuel produced by the Nevada plant. Enough is on hand for the next flight of the space shuttle. But what about subsequent flights? And how much fuel would have been available if shuttle flights hadn't been suspended following the Challenger disaster?