Under Fire Conditions Will Plastics Emit TOXIC FUMES?

Under Fire Conditions Will Plastics Emit TOXIC FUMES?

Typical of fire in such occupancies, 2.9 Louisville, Ky., firemen were overcome by acrid smoke in department store basement last November. Fumes were attributable to foam pillows—whether natural rubber or synthetic is not known. Bed linens, many wrapped in plastic, were damaged

—Louisville Courier-Journal photo

THE SUDDEN DEATHS of 125 persons, 30 years ago this month, was the harbinger of the hazards of the plastics age. On May 15, 1929, nitrocellulose X-ray film in a hospital basement storeroom began to decompose. Whether heat from a defective steam line in the room, a spark from X-ray apparatus or heat from an electric light bulb started the decomposition process is only an academic question today. In any event, a violent explosion occurred.

The rapid decomposition of the film liberated vast quantities of poisonous yellow fumes, which were sucked up throughout the building by the ventilating system.

The swift effect of the gas is best illustrated by the incident of the man who was brought out of the building by rescuers and who protested he was all right.

“Don’t do a thing for me,” he said. “The gas didn’t bother me. Get the others who are dying.”

Five minutes later he collapsed. Firemen lifted him into an ambulance and started him to a hospital. He was dead before he reached medical aid. You undoubtedly have recognized the disaster— the Cleveland Clinic explosion and fire, as reported in the May 29, 1929 issue of FIRE ENGINEERING.

It may seem far-fetched to cite a catastrophe of 30 years ago, especially since there is now no important domestic manufacture of nitrocellulose photographic film. However, according to a manufacturer of cellulose nitrate, a partial list of its uses today includes: Toilet seat covering, musical instruments, optical frames, dice, watch and clock crystals, piano keys, shoe heel covering, cutlery handles, templates, pens and pencils, and playing cards. Supplies of some of these products might very well be present in the stock room or on the counters of the average “five-and-ten,” novelty shop, department store or in a warehouse. In the event of a fire in such an occupancy, will the decomposition of these products add to the hazards and difficulty of fire fighting? In fact, may the thermal decomposition products of certain plastics not be the greatest hazard these modern-miracle materials pose to the fire fighter?

Relatively few departments are called on to protect plants manufacturing the basic resins or chemicals necessary for synthetic resins. But there is hardly a fire company in the country that may not be ealled upon to fight a fire in the cellar of a department store, five-and-ten, novelty shop, copiously stocked with plastic toys, novelties, ornaments and housewares.

However, the hazard of noxious fumes liberated when certain plastics decompose under fire conditions is not limited to the occupancies named above. For example, when fire gutted the interior of Donat’s Town Ho Inn, Milford, Conn., in 1952, a reporter-photographer for the Bridgeport Post and a fireman were overcome by fumes from burning plastic seat covers (FIRE ENGINEERING, October 1952).

Fire companies on New York’s upper West Side responded to what seemed an inconsequential fire on the quiet Sunday afternoon of April 5, 1959. The fire appeared to be in the basement furnace room of a garage and, since it looked like a trivial rubbish fire, the men did not wear masks. The smoke, however, was acrid and unbreathable. Within a few minutes, the men were feeling its effects.

Meanwhile, four manhole covers on an electrical conduit in the street, in front of the building, blew into the air. It was evident the fire was in the conduit and that the smoke, from burning insulation later identified by a representative of the utility company as neoprene, had seeped into the garage basement through the utility service connection to the building.

A lieutenant and five firemen were treated at a nearby hospital and the lieutenant and one firemen were kept at the hospital until the next day. After returning to quarters, a battalion chief became ill, was examined by a medical officer, relieved from duty and sent home.

Those exposed to the fumes became nauseated and complained of throat irritation resembling laryngitis. With some, the ill effects persisted for several days.

It is generally recognized that practically all combustible organic material including paper and wood, may evolve toxic gases or fumes when exposed to heat or flame. When these compounds containing carbon are burned, carbon dioxide is a product of the burning. If combustion is not complete, carbon monoxide will be present too.

Materials having other components such as combined chlorine or sulfur, for example, will produce irritating toxic gases which are compounds of chlorine and sulfur.

While it is granted that wood, paper, cotton, wool and other materials may evolve toxic gases under fire conditions, will plastics also emit such gases? Unfortunately, when one considers the great variety of plastics produced, there is very little information on the toxic products they release under fire conditions. Let us consider the meager information available, and see if any valid conclusions can be drawn.

Many plastics, when heated beyond a certain temperature, will emit irritating smokes but not all of these are toxic. The isocyanate resins (polyurethanes), polyethylene, nylon, the series of polymethacrylate esters, the fluorocarbons and the chloronapthalenes will emit toxic decomposition products when heated above a certain temperature.

Tests conducted by the U. S. bureau of Mines indicated that a specific group of thermosetting plastics used for electrical insulating purposes (phenolic and melamine resins) were capable of releasing carbon monoxide, cyanides and ammonia under the test conditions. In addition to these gases, the test atmospheres contained aldehydes, smoke and, in some instances, trace amounts of oxides of nitrogen, phenols and amines.1

In another group of tests conducted by the U. S. Bureau of Mines, it was shown that the primary hazardous products of the thermal decomposition released by polyvinyl chlorides and acrylonitrile materials were carbon monoxide and hydrogen chloride. Other decomposition products released in smaller amounts were aldehydes, ammonia, cyanides, and oxides of nitrogen. Additional agents such as chemicals used for the expansion of polyvinyl chloride may release volatile and toxic organic compounds in small quantities.2

The (British) Fire Besearch Board, considered the possible danger of production of phosgene during the combustion of some chlorinated plastics such as polyvinyl chloride or chlorinated methacrylate resins. The Board reported that the principal products of combustion were carbon dioxide, carbon monoxide and hydrochloric acid. Traces of phosgene were found in one or two instances but the amounts were relatively insignificant in comparison with other toxic gases. The presence of hydrogen chloride in addition to carbon monoxide increases the toxicity by comparison with ordinary cellulosic materials, but to offset this, hydrogen chloride by its irritating odor gives warning of its presence at a very low concentration so that suitable precautions can be taken.3

The pyrolysis products from polyethylene have not been definitely identified, but they are irritating to the eyes and to the respiratory tract.

The National Board of Fire Underwriters, in Special Interest Bulletin No. 49, points out that “All nitrocellulose materials produce very poisonous fumes. These may not immediately affect firemen and others breathing them, but several hours afterwards the person may collapse, and fatilities have occurred.” Fortunately, nitrocellulose is definitely declining in volume of production each year. Only 4,000,000 pounds were produced in 1958; this is one-tenth of a per cent of the total plastic production in 1958.

Battalion Chief Gustave E. Bonadio of the New York Fire Department, writing on “The Peril of Plastics,” tells of what at first appeared to be a routine telephone alarm at a Long Island City factory.

Upon arrival, firemen stretched a 2½inch line to the fire on the second floor of the building. The fire itself was nothing unusual. In fact, 14 sprinkler heads had fused and all flames had been extinguished. However, for the first few minutes and before complete ventilation had been effected, it was necessary to operate in an atmosphere tainted with reddish-brown fumes. Consequently, a few moments later, men were ill and reeling from the effects. Practically all required first aid and two were hospitalized.

The fire had involved about 2,000 large looseleaf salesmen’s volumes—as simple a combustion substance as you would expect to find anywhere, except that each page of every volume had been encased in a transparent plastic envelope.

Chief Bonadio goes on to mention that oxide of nitrogen, blamed for the deaths at the Cleveland Clinic fire, are not by any means the only gases that might be encountered when fighting fires involving plastics. He lists as other possibilities: Corrosive acid and alkaline vapors, hydrogen sulfide, hydrogen cyanide, chlorine, ammonia and vapors which contain phenol bodies. Most of these have been mentioned previously.

incomplete combustion

While die urea-formaldehyde resins, the melamine-formaldehyde resins, the unsaturated polyester resins, the alkyd resins, the epoxy resins, the silicones, the vinyls and the cellulosics, with the exception of cellulose nitrate, are not ordinarily listed as producers of toxic pyrolysis products, it should be rememered that in the case of incomplete combustion, carbon monoxide will be given off.

In an article on the hazards of synthetic plastics in the December 1950 issue of Mechanical Engineering, John V. Grimaldi, Ph.D., presently consultant on safety and plant protection, General Electric Company, New York City, notes that cellulose acetate and certain vinyl plastics when incompletely burned, produce acetic acid.

In general, according to Dr. Grimaldi, nitrogen-containing plastics, such as urea, melamine and aniline formaldehyde produce hydrogen cyanide and ammonia when incompletely burned.

The phenol-formaldehyde plastics, when overheated, will produce some phenol and formaldehyde.

The chlorine-containing plastics such as vinyl chloride and vinylidine chloride, when partially decomposed by overheating, will give off hydrochloric acid whose vapors are very caustic and irritating.

The plastics partially composed of glycerine, such as certain of the alkyd resins, may, when heated, decompose to give the highly toxic product, acrolein.

To keep the record straight, it should be noted that, in his conclusions, Dr. Grimaldi says, “The toxic products of combustion, while they must be considered, are for the most part of no greater danger than carbon monoxide, and this compound must be considered in the case of any fire.”

According to “Handbook of Industrial Loss Prevention,” prepared by the staff of the Factory Mutual Engineering Division, on application of flame, fluorocarbons deform slowly and the fumes are poisonous.

One manufacturer of TFE-fluorocarbon (tetrafluoroethylene) states, however, that “there have been no deaths or permanent injuries known to stem from the use of TFE resins in the products’ 20-year history. When TFE resins are heated in the 400°-600° F. range, minute quantities of decomposition products are evolved. If inhaled, these gaseous products may cause temporary symptoms similar to influenza. These symptoms do not appear until two to six hours after exposure, and pass off within 36 to 48 hours. On the other hand, many other resins, elastomers, and coating compositions yield fumes at these temperatures that are toxic, inflammable, or even explosive.”

In a memorandum on storage and fire control of these fluorocarbon resins, the same manufacturer advises, “If it is necessary lor people involved in controlling the fire to enter an area where they are exposed to fumes or vapors, they must be provided with a fresh-air supply, such as one would attain from a self-contained mask. Fumes from all fires, where paint wood or plastics are involved, are potentially hazardous and protection must be provided to prevent inhalation of such fumes.

“Further it should be realized that acid fumes may be evolved from the decomposition of plastic resins, which may cause skin irritation in the absence of protective clothing. Personnel involved in combating large scale fires should take the earliest opportunity to bathe and change clothes.”

Hazard of these gases

How dangerous are these various pyrolysis products that have been mentioned? The National Fire Protection Association, in its comprehensive and authoritative “Fire Gas Research Report,” makes the general observation that before the oxygen content has become so low as to be irrespirable, it may have taken up other toxic gases which would cause injury even in the presence of adequate oxygen supply and be more harmful than oxygen deficiency alone.

The same report points out that, in an actual fire, a single gas or vapor is seldom encountered and there is ample evidence to show that the sum of the toxicity potential of two or more gases or vapors is more than additive. And in a fire, the toxicity of such a mixture may be further increased by low oxygen concentrations and high temperatures.

Concerning hydrogen sulfide, which Chief Bonadio mentioned as one of the pyrolysis products of plastics, the NFPA report observes that carbon monoxide is only about one-quarter as toxic as hydrogen sulfide in equal concentrations. And every fire fighter realizes the hazard of carbon monoxide.

Regarding hydrogen cyanide, the NFPA reports that exposure to 100 parts per million, or 0.01 per cent, is very dangerous for even a short time. Exposure to 2,000 ppm is invariably fatal even with prompt treatment.

Chlorine, also mentioned by Chief Bonadio, is corrosive to the body surface or lungs in concentrations of .004—.006 per cent and can cause dangerous illness in one-half to one hour.

Nitrogen oxides are much more toxic than is commonly recognized, the NFPA observes, since in the water vapor of the lungs they form nitrous or nitric acids. Incidentally, the NFPA also reports that in the Cleveland clinic fire, 85 persons died immediately and 40 others developed fatal lung edema in two to eight hours after being rescued from the burning structure. In this fire, no excessive temperatures were reached and almost without exception, deaths were due to inhaling nitrogen oxides from burning nitrocellulose X-ray film.

Acetic acid vapor, which Dr. Grimaldi listed as an incomplete combustion product of cellulose acetate and certain vinyl plastics, is described in the NFPA report as corrosive. The corrosive acids can produce skin burns and are dangerous, for even though they do not burn, they may vaporize and damage the lungs when inhaled.

As the National Board of Fire Underwriters points out in Research Report No. 1, “Fire Hazards of the Plastics Industry,” “The type and concentration of toxic gases produced by the thermal decomposition of various plastics depends upon the individual characteristics of the plastic material and all of its components. In any specific case the following factors are involved: (a) quantity of material affected; (b) type of combustion (fire); (c) size of enclosure; (d) rate of ventilation; (e) temperature and duration of heat application.”


Earlier in this article we conceded that wood, paper, cotton, wool and other materials may evolve toxic gases under fire conditions, and asked if plastics would also emit such gases. The experiences of fire fighters which we have related, the investigations of the Bureau of Mines and Dr. Grimaldi’s findings indicate that some plastics do give off toxic gases upon thermal decomposition. Unfortunately, there is not much other information available on the subject.

This writer would like to see the Committee on Fire Prevention of The Society of the Plastics Industry institute extensive research on the toxic decomposition products of plastics (the surface has barely been scratched in this article), and make its findings known to the fire service.

Some segments of the industry may feel that the release of such information to the fire service might eventually leak out to the general public and cause the industry great harm. It appears to this writer, however, that just as the isolated, finished plastic product normally found in the average home, with the exception of cellulose nitrate, poses no unusual fire hazard, so also the isolated plastic item in the home may present no decomposition danger. The danger exists for fire fighters called to fight a fire in a large, and sometimes varied, stock of plastic products. If there is a plastic product where a single item accidentally decomposing in the home could present a toxicity hazard, the general public should be apprised of the dangers and precautions to be taken, possibly through labeling the product.

It may be, too, that departments which maintain their own laboratories may be interested in conducting experiments on this subject. If such experiments, or experiences with plastics under fire conditions are reported to the Editors of FIRE ENGINEERING, the information will be made available in a future article.


In view of the potentially hazardous fumes which may be encountered in plastics fires, preventive measures are indicated. As the NBFU Report notes, insistence on proper location of materials in storage and during processing, good ventilation facilities in the building and sprinkler protection will tend to reduce the toxic gas hazard to a minimum.

But if, despite all precautions, a fire breaks out in plastics, what can be done to protect the fire fighter? The NBFU recommends prompt ventilation, absorption of the gases with finely dispersed water streams, pre-fire planning and the use of approved respiratory equipment.

The choice of specific respiratory equipment would depend on the factors previously mentioned: quantity of material affected; type of combustion; size of enclosure; rate of ventilation; temperature and duration of heat application.

Since we know that certain plastics release toxic gases under fire conditions and since it’s possible that other plastics on which there is no definite information also evolve such gases, officers should insist on firemen wearing masks at plastics fire. As John B. Dunne pointed out in an article in the April, 1959, issue of FIRE ENGINEERING, “… men often resist wearing masks. Let’s face it. Very few people like to be encumbered by a mask.” We have all known “smokeeaters” who would rather take a quick “feed” than bother with a mask. In fact, Mr. Dunne tells of “a smoke-eating deputy chief in a large city” who scoffed at the idea of a respiratory safety program (they had a particularly bad record for smoke inhalation cases), ’Hell, fire fighting isn’t a safe business and we don’t want these guys thinking about their own safety.” But more firemen are put out of action every day by inhalation of smoke and gases than by any other cause.

In conclusion, the purpose of these articles has not been to scare anyone concerning the hazards of plastics nor to crusade against them. They have been written with the hope of protecting the fireman. Plastics are here to stay, the industry is one of the fastest growing in the country! But for this very reason, the fire fighter should know what he is up against when he fights a plastics fire, and take the indicated precautions. It would he as unrealistic to castigate plastics as to avoid autos because they use volatile, flammable fuel, or to pass up air travel because planes occasionally crash. Almost every advance in our standard of living has been accompanied by certain hazards. We have, however, enjoyed the benefits and taken precautions against the hazards. This is the only sensible policy to follow.

Continued on page 417


1 Report of Investigation—4734—“Toxicity and Flame Resistance of Thermosetting Plastics” —U. S. Bureau of Mines, October 1947.

2Report of Investigation—4777—“Thermal Decomposition Products and Burning Characteristics of Some Synthetic Low-Density Cellular Materials”—U. S. Bureau of Mines. January 1951.

3Fire Research 1952, Department of Scientific & Industrial Research and Fire Officers’ Committee, London, 1953, Her Majesty’s Stationery Office.

The Peril of Plastics, by Gustave E. Bonadio, WNYF, publication of the New York Fire Department, July 1945.

The Hazards of Synthetic Plastics, by John V. Grimaldi, Ph.D., Mechanical Engineering, December 1950.

NFPA Fire Gas Research Report, NFPA Quarterly, Vol. 45, No. 3, January 1952.


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