Another one in the series of books found in the bibliography of Heinrich’s 1931 version of Industrial Accident Prevention. I am trying to follow up all of these books in order to get some measure of their influence on Heinrich’s work. My main focus with this review/summary (and others) is an attempt to distil the main threads and a comparison to Heinrich’s book, and - in a later phase - to the other safety handbooks that came out around the same time.

DeBlois was a graduate from the Harvard School of Engineering, 1899 class, and had been organising the safety work in DuPont from 1907 onwards and became their first (I believe) VP of Safety. He also was the co-founder and first president of the Delaware Safety Council (DuPont was located in Delaware). The council started in 1918 or 1919. The Delaware Safety Council was the brainchild of Irenee DuPont - the President and owner of DuPont - and DeBlois.

In 1920, he was chosen as vice president of the National Safety Council, and in 1923, he took over as the NSC’s president. After 22 years with the company, he resigned from DuPont to take a position in NYC in May 1926 as executive vice-president of the Greater New York Safety Council. In 1929, he became the Director of Safety Engineering Division of the National Bureau of Casualty and Underwriters in NYC. After that he faded a bit out of sight. He passed away Sunday, 26 February 1967 in his home in Sharon, Connecticut, aged 83.

“The future progress of the safety movement, the decision whether it shall advance with sufficient speed and strength to enable it to overtake the apparent increase in industrial accidents for which mass production and mechanical methods are largely responsible, rests with three groups: industrial executives, the engineering fraternity and that smaller and newer group, the safety engineers. I have named them in what I believe to be the order of their importance as factors controlling the destiny of industrial accident prevention.” (DeBlois, 1926, p.vii)

DeBlois’ book stands out from the others from the era. This may be partly due to his academic background, and certainly his experience in DuPont and various safety organisations have left their marks. Somehow, the book failed to have the same impact as Industrial Accident Prevention (published by the same publisher) would have only five years later, even though there seem to have been several reprints in 1929, 1934, 1935 and 1936. What the reason is for this book having been more or less forgotten in the course of time, and Heinrich’s book still being cited? I don’t know! One reason may be a matter of timing, another the way the subjects are presented. Heinrich’s book has definitely a more practical approach that should appeal to managers and safety practitioners in need of solutions. In places DeBlois’ book is probably more advanced, more reflective, nuanced and philosophical (all of which justifies a somewhat longer discussion). That makes it - despite its enthusiasm and passion for safety - less accessible and more difficult to use in the work of everyday. Let us have a look in greater detail…

The title makes quite clear what the main focus of the book is, and what audience DeBlois aims to address. Practical safety work as protection and guarding is rather absent (although chapters 17 and 18 deal with various hazards and the principles of protection, including design ad PPE) and the main focus is on safety organisation (or as we might call it today, safety management) and some underlying principles of safety and accident prevention.

Let us start with the latter. After a discussion of statistics on accidents and accident reduction (with an acknowledgement of unreliable data and the importance of leadership - according to DeBlois executives are the most important for success in safety) in the first two chapters, Chapter 3 offers the Fundamental Requirements of Safety. According to DeBlois, the absence of these is the prime problem for lack of progress (p.32). The 7 points are the basic mental concepts necessary for successful accident prevention work (p.33/34):

  1. Accidents are destructive and wasteful
  2. Prevention is morally, ethically and economically justified
  3. Methods of prevention are protection, instruction, removal/reduction of hazard, with emphasis on safety education
  4. Safety education deals firstly with value of human life and preventability of accidents and the application of these concepts
  5. To eliminate accidents these concepts must have infiltrated all minds, leading to safe thought, habits and action and counter the rise of unsafe practices and conditions.
  6. Organisation is the way to educate the individual and mobilise the necessary movement
  7. Safety organisation shall educate, stimulate and develop, but action has to follow normal, functional lines.

In a way, one can regard this list as an alternative to Heinrich’s Axioms (1941), but their nature is somewhat different, despite some overlaps. Throughout the book, DeBlois puts a greater stress on embracing safety as a way of thinking and we see some more leanings towards thinking of safety in terms of a religion (mostly by quoting others, by the way).

Chapters 4 and 5 are the ones where DeBlois truly stands apart from his contemporaries, dealing with Accident Investigation and Analysis and Chance and Probability respectively. It is easy to assume that Chapter 4 had a major influence on Heinrich’s work. Here we find the (or at least, an) origin of thinking of accidents as a process. Accidents and their consequences (injuries) are separate. There are causes of the event and causes for the consequences. DeBlois clarifies that, although connected, injury and accident are two distinctly different things with usually distinct causes. While an injury is the consequence of the accident, the accident does not need to end up in an injury. This thought we find directly back in Heinrich’s writing, most importantly when he introduces the triangle.

DeBlois’ understanding of ‘accident’ as an unwanted or unexpected event, regardless the consequences, was most likely adopted by Heinrich. Where Heinrich and DeBlois differ, is their focus on proximate causes. Heinrich rather aims for the quick practical solution, while DeBlois to a much greater degree embraces multi-causality (which Heinrich does not deny!) and complexity:

“Most accidents are not the result of a single, well-defined cause but of a train of events or combination of circumstances each of which contributes in some degree to cause the final accident and consequent injury. Many superficially simple industrial accidents arise out of a highly involved network of condition and circumstance. They appear simple solely because we do not make the effort to trace the causative relationship to its source and are content merely with what is termed proximate cause.” (p.47, emphasis in original)

Many modern scholars would like this! As said, DeBlois is not as adamant about the proximate cause as the point of attack as Heinrich is. It may or may not be the best to address, but you have to look at all the other causes to be sure. DeBlois instead proposed the “principal remedial cause” which he defines as “that cause which is most readily and effectively remediable, and the remedy of which will go farthest towards the possibility of repetition” (p.48). This corresponds to some contemporary definitions of “root cause”. DeBlois suggested a more thorough analysis than just aiming for a direct cause. After this, the feasibility and efficacy of actions to ‘remove’ particular causes should be identified.

And while knowledge about causes is regarded as very important, in some cases neither the proximate nor the “principal remedial cause” are the logical point for prevention. DeBlois suggests that some cases share common causes (p.52): a contributory cause in a group of accidents which may be wiser to attack than a great variety of proximate causes. In DeBlois’ case, the type of accident does not need to be the same (which Heinrich suggests), it is more in the ‘modern’ line of thinking that actions on underlying causes can have a further reaching effect than actions on direct causes (e.g. the lack of a good maintenance program can be a underlying cause for a wide variety of accidents).

Chapter 5, Chance and Probability, is definitely groundbreaking. Some safety thinkers had mentioned risk before, but not one before (that I know of) and not before many years after, have I seen such a detailed and explicit discussion of the role of probability in safety. Risk as a common concept in occupational safety was still a couple of decades in the future, yet here it is already on six pages that were ahead of their time!

After this, DeBlois turns to Responsibility, yet not primarily related to the various functions in the organisation (as Heinrich would discuss the subject) but more in a sense of causation (and as such a more logic successor to Chapter 4 than the one on Risk). However, DeBlois also points towards the employer as the one with the main responsibility. This chapter is fascinating because DeBlois (like Lange before him) is very critical of single causation and single responsibility:

“…the simplest way out of the tangle of causes and circumstances that are brought to light by thorough accident investigation lies in the selection of a single cause and a single responsibility for each accident, and this greatly simplifies any ensuing statistical procedure, but since accidents occur as the result of combinations of circumstances or causes, the responsibility for all of which can rarely be attributed with any fairness to a single individual, any tendency to fix the blame on one man or regard responsibility as analytically indivisible will ultimately cloud rather than clarify the issue.” (p.59/60)

Now one can remark that Heinrich did not develop his 88:10:2 ratio with the aim to assign blame or responsibility, but one still wonders what he thought of this passage, even more when DeBlois proceeds and is critical of “the oft-repeated statement that 75 to 90% of industrial accidents are the fault of the men themselves.” He even underlines this critique by concluding,

“…the statement as usually made is not only fallacious but, by causing resentment on the part of those whom it is intended to correct, has hindered rather than hastened the progress of the safety movement.” (p.60)

This precedes the Heinrich/Blake debate on the subject by 30 years! And while Heinrich merely intended to point at the ‘most important’ cause without blame in thought, DeBlois already points out some of the problems and possible misunderstandings.

The next two chapters deal with accident records and statistics. Somewhat boring due to a lengthy discussion of various rates, but in-between ‘indirect costs’ (p.67) briefly pop up.

The next 7 to 8 chapters then concentrate on Organisation and committees, how they work, what their roles are and so on. There is also a chapter on Safety Engineers, much about what kind of person they should be, the importance of their enthusiasm for safety and even attention for their salary and possibilities for promotion.

Earlier on, I said that DeBlois’ book in places is the most advanced of the early safety books, when it comes to Chapter 14, however, he surprises with a rather uncritical discussion of ‘Stimulating Rivalry’ and making safety into a contest, the presentation of accident scores on billboards and no-accident contests. Here Heinrich showed a much more critical attitude, but not DeBlois who is in favour of these practices without any nuances or discussion of downside (even though he acknowledges the reaction towards those who ‘spoil’ the record). Maybe a DuPont thing?

Chapter 15 continues the subject with Maintaining Interest and a variety of organisational tools - including using emotion as a driver for safety (familiar also today!). Interesting is DeBlois’ critical stance towards bonuses for safety.

The Human Factor (a term DeBlois actually uses!!) is discussed in various chapters through the book, but the first time it really steps to the front is in Chapter 16 about Safety Rules (together with Lange we here have an author discussing them explicitly), including a discussion of discipline, and sections on the New Man. This is one of the rare occasions that proneness is discussed, as it is in Chapter 19 with some lengthy discussions of mental and physical examinations and selection (or selective letting go…) as tools to prevent accidents, and in the section about non-English speaking workers. Interestingly, DeBlois here nuances the possibility of proneness by suggesting that these people are often employed in higher risk occupations or companies without proper provisions. In chapter 16, we also find a section on ‘creating culture’, here called Safety Atmosphere:

“…that indefinable influence which pervades the industrial plant that is doing conscientious safety work and reaches, instinctively, even the new employee himself.” (p.156)

In the chapter that discusses safety, production and the human factor (21), DeBlois draws strongly on the work of Boyd Fisher (1922) and his main categories of ‘mental causes of accidents’, spiced up with many quotes from other relevant authors. Interesting is that little of what is discussed would be counted as psychology these days, but most deals with ergonomics. Here we also find a lengthy section on illumination, something that other authors discuss in terms of conditions - which only illustrates how arbitrary the division between men and conditions can be…

Chapters 20, 21 and 22 deal with Safety and Production, and Safety and Efficiency. The first of these focuses on equipment, costs of safety (drawing on the work of Sidney Williams - p.212), the importance of preventive maintenance (basically also an argument for reliability), and interesting insights on conflicting objectives (e.g. how speeding up work can be negative for both safety and production in the long run). After concentrating on the Human Factor (DeBlois seems to acknowledge men and machine as two main categories but gives no greater attention to this duality), the author then discusses the correlation of safety and efficiency. Here he doesn’t just accept the widespread common sense belief that a safe plant is an efficient plant, but after reviewing some literature he builds a qualitative argument by moving through various elements (accidents, routine, emergency, equipment, humans and management) and concludes that based on these deductions safety and efficiency should correlate - but argues also for the need for fundamental research.

The final chapter, Safety and Human Relations, touches on motivation, sees safety as a door into improving other elements of the industrial relationships and returns to the various motivations of safety - economical, moral, humanitarian and spiritual. In this chapter, we also find a lengthy quote of Albert Whitney arguing about positive and negative views of safety (super modern!) as well as an argument that risk makes sense - life without adventure is not worthwhile.

The end section may serve as an illustration why Heinrich’s book may have had a greater impact than DeBlois’ partly intellectually superior work. Where Heinrich gives a wrap up, an encouraging sense of “You can do this” and ends with something in the line of “now get busy”, DeBlois ends philosophical and with a question. Heinrich delivered the better management self-help handbook, despite some deficiencies…


DeBlois, L.A. (1926) Industrial Safety Organization for Executive and Engineer. New York: McGraw-Hill.

You can read the book online - and download it: