I was actually looking for another book of almost the same title when I came across this and it tickled my interest. Read it over the weekend, and surely not wasted time. The book is accessible and well-written and should appeal to safety people as well as to interested laypersons. It is neither technical, nor does it actually give an answer to the question posed in the title. Instead, Lewis takes us on a journey where he sheds some light on the various factors and difficulties in answering that question.

The first chapter sets the scene, comparing the past (and the journey to today) to give some perspective about how (un)safe we really are. The next six chapters then take us through various factors in determining how safe things are for us: the (technical) lifecycle of systems, trade-offs, finding faults, the human factor, cultures of safety and regulation. The five chapters that follow, then, look into major hazard groups (loosely based on what research into risk perception has taught us), being every-day risks (automobile-related, occupational and home risks), man-made disasters, natural disasters and possible future long-term health hazards. While not discussing risk perception extensively, it is one of the themes that runs through it: are we afraid of the things that matter most (home and road accidents kill more people than the dread disasters we fear; we are safer than ever before in history)?

Another theme that returns and returns (justly) in many variations is that of trade-offs and conflicting objectives. Lewis does a great job illustrating this essential point. We cannot have absolute safety. There are limits. Safety is not first. And there will be side-effects with any choice. Very well done.

Another positive thing about the book is its story-telling form. Lewis teaches by using many and varied examples (some a bit lightweight, like attributing the Costa Concordia accident to the “captain’s recklessness”). There is hardly any discussion of methods or tools - a tiny bit on Cost Benefit Analysis being the main exception, including a discussion of problems and limitations with CBA (I would have expected some Adams there, by the way).

Some critical remarks, for good measure:

• In the editing process somehow an unbalance went unnoticed between the safety-definition in the safety-reliability discussion, and previous discussions of safety (i.c. safety is NOT absence of hazards!).
• The discussion of culture is not of the same level as the rest of the book. I think Lewis is outside his field of expertise in that chapter. I struggle when I read about “cultures that are too poverty stricken to apply it to safety” (p.99). Lewis does not have a strong normative tone, but I think this discussion needs much more nuance - and no norm at all. Besides, the ‘explanation’ of the Katerine disaster as a result of lack of culture of safety in a rather incomplete tale, and not convincing. Social, political and organisational factors would make for better explanations, I think.
• The book is rather US-oriented, but hey, you can handle this.

As a whole, an enjoyable read that highlights ethical considerations in safety (choices).

Lewis, E.E. (2014) How Safe Is Safe Enough? Technological Risks, Real and Perceived. New York: Carrel Books.