Mr. YANT. Yes; after we have applied methods of preventing the formation of dust, then we go to ventilation and dust removal. That is merely a problem of ventilation similar to the ventilation incident to taking out mine gases. That is a well-known practice and is followed by many times. In fact, the art of ventilation is perhaps developed highest in coal mines, because there are explosive gases there. More air is needed in those situations than in tunneling or metal mining.

The third defense is personal protection. I refer to the use of respirators. After the dust has been taken care of at the point of formation and by ventilation, if you have not reduced it to a threshold concentration, and you cannot do it practically, then the final thing to do is to furnish the men individual protection by way of respirators.

In addition to that, of course, one should make sure that he is on the safe side by employing medical supervision and examination both before and after the man goes to work. Moreover, there should be a check-up during the time of employment to ascertain whether or not there is any silicosis production. Then, too, a man should be examined when he is leaving the employ of a concern.

Mr. GRISWOLD. How often would you suggest that the employees working where they are exposed to silica should be examined medically?

Mr. YANT. I think they should be examined before they go to work, at certain periods while they are at work, and when they leave the work. I am going on the basis of dust control. These projects ought to have some person to make a check on the control of the atmosphere to which the men are exposed by known methods of sampling and analysis. Then if the dust concentration is low, I would think that yearly checks would be enough. This is, however, a matter for medical treatment rather than for treatment by me, a chemist.

I am simply using this as an example. If the dust concentration is high, I would have the examination made quite often. If one found after one or two periods that the men were not developing silicosis, then the periods of examination could be extended. The examinations, anyway, should be made often enough to know that if there is any silicosis it will be caught in the beginning.

Mr. GRISWOLD. I think that all who have appeared here have testified that silicosis is a progressive disease, and I am wondering just how often individuals should be examined, and conditions should be examined, in order to best protect the individual.

Mr. YANT, If a man is showing signs of silicosis, or if there is a doubtful condition, and one does not know whether it is silicosis or not, that person should be called up for examination again within, say, 6 months without question.

We know enough of these conditions and of the disease, and of the conditions that caused the disease, I think, to take care of any tunnel situation or any mine situation.

In taking care of it, it might not always be the most practical thing to do, but it can be done.

What we are looking to is improving of control methods, and to make them more practical, so that they will be more readily accepted. First of all, we need a better method of protection. I mean that the methods we have are inaccurate and they do not give a suitable

index. These are methods largely used by trained technicians. What we need is a simple method whereby a, say, foreman or inspector can walk into a tunnel and tell in 1 or 2 or 5 minutes whether there is a good or bad condition. We need a procedure such as is used in mines, where an experienced person may walk into a face, hold up a lamp, and determine that there is too much gas. That method is not fully available in tunnel work. We need something easier in connection with tunnel work. We need to go to better methods of dust control or dust prevention.

Certain things are being suggested now and certain procedures are under investigation for trapping dust as drilled. That does not involve using water, but is a system whereby the dust would be trapped at the drill.

Mr. YANT. By putting a collar around the drill. There are some of those in use now. The collar goes around the drill and catches

the dust. The collar conveys the dust back through a trap.

That apparatus has some impractical features. It will not work universally. There is an English apparatus known as the Hay trap; and there are others of that type.

Mr. GRISWOLD. They work on the order of a vacuum sweeper, do they?

Mr. YANT. Yes; they suck the dust right at the drill.

There are other means being devised, developments for recirculating the air rather than bringing in fresh air.

Mr. GRISWOLD. Conditioning the air, you mean?

Mr. YANT. Yes.

Mr. GRISWOLD. You would clean the air?

Mr. YANT. Yes; then there are suggestions to use fire foam. That system has some practical features and some that are not so practical.

Mr. GRISWOLD. You know, from hearing the testimony here or from reading about it, the situation at Gauley Bridge, do you not? Mr. YANT. Yes.

Mr. GRISWOLD. According to the testimony you heard, was any effort used to employ any of the later means of curing this condition? Mr. YANT. These have come out largely since that time, since that Gauley Bridge construction.

Mr. MARCANTONIO. Such as the suction method?

Mr. YANT. Yes.

Mr. MARCANTONIO. But the idea of drilling wet and providing adequate ventilation is an old one?

Mr. YANT. Yes; we have put out a publication or two on that subject nearly every year since that time, and we have taught it. We have educated people in that until some of the mining companies have taken it and progressive companies very largely have put it into effect.

Mr. DUNN of Pennsylvania. You speak of progressive companies. Can you give us the names of some of those companies?

Mr. YANT. I should not like to do that.

Mr. GRISWOLD. I do not think that we ought to require the witness to differentiate. Anyway, it is a matter of opinion.

Mr. MARCANTONIO. Referring to methods of prevention, wet drilling was known and extensively used prior to construction of this tunnel, was it not?

Mr. YANT. Yes.

... Mr. MARCANTONIO. And proper vent fans and systems of ventilation were widely used?

Mr. YANT. Yes.

Mr. MARCANTONIO. Masks also were known and used?

Mr. YANT. We did not have approved respirators, but they were known, and there were some of good quality sold.

Mr. MARCANTONIO. Respirators of good quality were sold before 1930?

Mr. YANT. Yes.

Mr. MARCANTONIO. So that in fact the only new method of prevention which has developed since the commencement of the construction of that tunnel is the suction plan, is it not?

Mr. YANT. Yes; and even that was talked of and understood among persons who were primarily interested in this work before that, but it was not generally known.

Mr. MARCANTONIO. Any engineer, no matter how limited his experience or knowledge, when working in a tunnel where the test drillings had shown 97 percent silica content, would have inquired, naturally, as to methods of prevention, if he were properly interested in the welfare of the workers? Is not that true?

Mr. YANT. You are asking for an opinion as to the appreciation of silicosis by construction engineers. I should say that if the man were experienced in tunnel work, he would know that.

Mr. GRISWOLD. You heard the testimony here in regard to the ventilation system in use at the Hawks Nest tunnel at Gauley Bridge, did you not?

Mr. YANT. Yes; I heard that there was a 2-foot duct, 24 inches. Mr. MARCANTONIO. That is right, it was 24 inches.

Mr. GRISWOLD. But the line was broken in places. Rocks had fallen on the ventilating line, broken it, and it had not been repaired. There were leaks in the ventilating line. That is the testimony we had here.

Mr. YANT. I did not hear that.

Mr. GRISWOLD. Assuming that to be true, would you say that the Gauley Bridge ventilation system was a proper one and the best system for work of that kind?

Mr. YANT. I would not say it was a proper one if it had holes in it, that caused leakage. That would not be a good ventiliating sys

tem.

Mr. MARCANTONIO. Even without leakage of air, a 24-inch ventilator would not be appropriate for a place like that, would it?

Mr. YANT. If I knew the horsepower of the fan and the pressure, I could give you a pretty good idea as to that. It is hard to say what a 24-inch duct will carry. That depends quite largely upon what one puts in at the other end.

Mr. MARCANTONIO. This is a 32-foot tunnel, and it is 334 miles long.

Mr. YANT. So I understand.

Mr. MARCANTONIO. Much larger ventilators have been used for smaller tunnels than that, have they not?

Mr. YANT. Yes. The amount of air required would be according to the amount of dust produced and the manner in which air was put in.

There are two points to consider: First, was the air enough, and was it put in in such a way as to reduce dust concentration for the

men at the head; second place, was it sufficient to dilute all that dust to a concentration below the threshold after it passed back through the tunnel to the rest of the men?

Mr. MARCANTONIO. In smaller tunnels, as regards diameter and length, larger ventilators than 24-inch have been used, have they not? Mr. YANT. Yes. Sometimes they are used for cooling purposes. Sometimes they are used because it is too hot to work. Sometimes they are used for taking out powder smoke and clearing up the heading as soon as practicable.

There are other factors that enter besides the dust factor.

I have spoken of the better method of prevention and detection. The most important feature in dealing with a silicosis condition or dust diseases in general is to know what you have and what you are dealing with. That does not have to be precise. It merely means the determination of whether it is good or bad. If bad, it needs some correction, obviously. The second need is a better method of diagnosing silicosis. We can tell in advanced stages, but we need something that is not subject to personal opinion so much as present methods.

Mr. GRISWOLD. You will have a hard time getting away from that. I am speaking from this standpoint: One doctor diagnoses silicosis as something and another doctor diagnoses it as something else. There seems to be no exact diagnosis in connection with any disease, because the medical profession is not an exact science.

Mr. YANT. But it is approaching that.

Mr. GRISWOLD. Even blood tests, whether one has a positive or a negative, there is a range where there is a doubt.

Mr. YANT. Yes. Even in anemia the average man should have five million or five and a half million. When does anemia begin? We are going closer to more precise methods of diagnosis all the time.

In red lead poisoning they used to look for clinical signs and manifestations. Now we are putting more stress upon chemical findings, such as what the analysis of urine show. That is true of silicosis also.

Mr. MARCANTONIO. Are urine tests being made in connection with silicosis?

Mr. YANT. Yes. They are made to determine whether they are reliable and mean anything in relation to that disease. The idea is to learn how much silica is secreted in the urine. There may be other methods developed, but we need something more precise in the matter.

Mr. MARCANTONIO. This is a very unusual situation when men are required to work in a very heavy concentration of silica dust, such as they were at the Hawks Nest Tunnel at or near Gauley Bridge. I have spoken to doctors about this matter, and I hope to bring one here from New York who has made an exhaustive study of silicosis. Mr. YANT. That would not be considered good mining practice, if the practice has been accurately described here.

Mr. MARCANTONIO. Assuming the conditions to be as they have been described here, such a situation is very unusual, and medical practice has not been confronted with this situation very often; is not that true?

Mr. YANT. Yes.

Mr. MARCANTONIO. So that the immediate development of silicosis in a situation such as has been described for Gauley Bridge, while it is rare it is nevertheless possible, you would say?

Mr. YANT. Yes; I do not think anyone could properly say that

it is not.

Mr. MARCANTONIO. One more question. You realize that in order to get an opinion we have to assume certain alleged facts to be true. Let us assume that the recitals by witnesses here are true, and they have not been contradicted. Let us assume a situation where prior to the construction of the tunnel test drilling showed 97 percent silica rock, which is almost pure silica; assume that immediately after blasting the men were sent back to work; assume that the dust was so thick that one could not see 10 feet

Mr. YANT. There was no water?

Mr. MARCANTONIO. I will come to that. Assume that the dust in the tunnel was so thick that one could not see 10 feet or beyond 10 feet; assume that the vent tubes were inadequate; assume that there were 16 drills in operation at all times, 6 diagonal wet drills and 10 vertical dry drills; assume that the bureau of mines of the State of West Virginia had warned the contractors to desist from these practices which I have described; what is your opinion as to the degree of negligence by the contractor of this tunnel?

Mr. YANT. I will say this much, that it would be a very poor practice.

Mr. MARCANTONIO. Would you not consider the contractor to be extremely negligent? You are not stating the facts, but assume that the alleged facts are true. Further, let us assume, as has been reliably testified here, that the vent fan had been broken in certain parts.

Mr. YANT. I would still say that we would consider that poor practice. As to negligence, I am not legal man enough to know whether there was legal negligence; but I will say that I would consider it negligence in the face of good engineering practice.

Mr. MARCANTONIO. I am discussing negligence from an engineering standpoint.

Mr. YANT. Yes. In the face of good engineering practice I would say there was negligence.

Mr. MARCANTONIO. It would properly be called gross negligence from an engineering standpoint, would it not?

Mr. YANT. You can so characterize it if you wish. To say there was negligence is enough for me in any situation of that kind. It would be a practice that many mines would not permit. In many of our mines it is not any longer only a question of how bad the condition is; it is a question of merely helping to check up and improve conditions in order to promote and maintain the health of the workers.

Mr. MARCANTONIO. Assume that this were a Federal project and under the jurisdiction of the United States Bureau of Mines.

Mr. YANT. In that case we would not permit such practices. Mr. DUNN of Pennsylvania. Your organization would stop them? Mr. YANT. Yes; we would stop the practices. We would not stop construction of the tunnel; but we would effect methods and procedures by which the tunnel construction could go on without the dust and with safety to the lives and health of the workers.