Midday dinner, an unknown hazard, went off smoothly.

There was danger from the heated earth and the rumbling mountain, but this known hazard militated against unknown hazards.

Would others have preferred a marginally effective treatment with known hazards to an experimental one with unknown hazards?

Critics also worry about unknown hazards.

But it came with the job of warlord, with all the unknown hazards and duties that must surely imply.

Somehow, the new adventure that he was undertaking struck her as a duty surrounded by great and unknown hazards.

How could it be causing a previously unknown hazard?

Some were unknown or minor hazards only a decade or two ago.

Often they were deeply entangled in the guts of an alien technology or a derelict spacecraft before unknown hazards presented themselves.

Then he led them away to gather supplies for an extended journey into the unknown hazards of time.