Toxic combustion products of wood and polystyrene

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Toxic combustion products of wood and polystyrene

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TOXIC COMBUSTION PRODUCTS

OF

WOOD AND P O L Y S T Y R E N E

Kikuo Sumi and Yoshio Tsuchiya

Toxic g a s e s and vapours produced at f i r e s are responsible f o r

the majority of deaths at building f i r e s . Information on the gases

causing the se deaths is scarce because of lack of detailed pathological

examination of victims.

It is generally

as a w e d that carbon monoxide

{GO)

i s the moat important toxic gas produced at fires because it is one

of the main combustion products from cellulosic rnatdrials that are consumed in quantity at most building fires, The increasing u s e of new materials, such as polystyrene, r a i s e s the possibility that when

involved in fire they may increase the toxic gases produced at fires.

The purpose of this Note is to provide data on the toxic gases

produced from

the

combuetion of white pine and untreated polystyrene,

and evaluate the toxic hazard that is created by the cornbustion products.

EXPERIMENTAL

Specimens were made in the foxm of pellets f r o m white pine

sawdust and untreated expanded polystyrene, and burned at 800°C in

a 5-litre flask containing air. The sample weight was varied s o that

the range of weights would cover the condition for producing the maximum

m o u n t of

G O

per g r a m of sample.

The gaseous combustion producte w e r e cooled k d collected in

an evacuated bottle, The a m o u n t s of carbon monoxide and carbon

dioxide

(C

OZ)

w e

re

then quantitatively analyzed by gas chromatography.

RESULTS

The experimental results are presented in Tables 1A and 1B.

The data f o r C O and COZ are expressed in weight p e r weight of sample.

DISCUSSION

Toxicity hazard due te the products

C O

and C

O2

was calculated by a method proposed by the present authors('). B r i e f l y , the method

(4)

of evaluation is as follows:

Toxicity, t , due to a gaseous or volatile product is assumed to

be proportional to its concentration. c , and t o its relative toxicity, t,.

Relative toxicity is defined as

where cf is the concentration of the g a s e o u s product that is fatal to man in a short exposure

of

about 30 minutes. The toxicity of a product based

on both the nature of the rnaterial and the quantity evolved, then becomes

In o r d e r to present data an toxicity in

a

consistent manner, the authors

suggest using the equation

where T i e the toxicity index of a gaseous product, and ce ie the concentration of the produci evolved when one gram of material is de -

3

composed, and the products are diffuaed in a vc>lume

of

I

rn

.

Concen- trations, c e and cf, a r e expressed in ppm. The toxicity index

of

the material is obtained from the s u m

of

the toxicity Indicea of the products.

The toxicity indices obtained f r a m the results of the present experiments using

cf

=

4000 ppm for

c d 2 )

and 70,000 to 100,000 ppm

for

~ 0 ~ ( ~ )

are presented in Tables

2A

and

ZB.

When wood is decomposed by heat, a large variety of combustible gases and VapolUFs are produced. S o m e

of

these products a c t as mild

irritants to the eyes and reepiratory tract. W h e n wood is burned, a large proportion of these vapours are

consumed by

the fire. The max- imum toxicity index for w o o 4 based on the present experirnents was 0 . 09.

The toxicity

due

to

G O

and GO2 only w e r e considered Ln Table 1A because

the amounts of other thermal decmposition products found inthe present

(5)

Zn o r d e r t o discuss the contribution of styrene to the toxicity of

the ahnosphere following c a n b u s t i o n of polystyrene, the lethal concen-

tration, cf, of styrene is required. This information could not

be

found i n the literature, and an estimate had to be made, It was assumed that

the lethal concentration of styrene is similar to those of benzene, toluene and xylene. The maximurn concentration of these three compounds that can be inhaled for one hour without serious disturbance is reported as

3130 t o 4700 ppm, and the concentration that i s fatal f o r even a short exposure as 19,000 ppm ( I , 9 per cent). The lethal concentration far a 3 0 -minute exposure is probably somewhere between these figures, and

f o r the present discussion, is estimated to be 1 per cent or 10,000 p p

f o r benzene, toluene, xylene and styrene.

If polystyrene is completely d e c m p o s e d t o styrene monomer in the absence of air, the calculated toxicity index for styrene is 0.02. This

theoretical value is much less than the toxicity i n d e x from

C O

obtained fr

orn

experimental results, The toxicity h d e x f o r

G O

ranged from 0,065

to

a.

0 9 2 , as presented in_Table_{218. The}_maximum_{toxicity index f o r}

polystyrene obtained f r o m CQ and C 0 2 data of the pre. sent study was 0-10.

Even if the remaining carbon a t o m s of the sample w e r e all converted to styrene (which is not possible in _{practice) the toxicity}_index_{f o r}_styrene

would only be 0,005.

Thus,

C O

is the main toxic product f o r m e d from the combustion of polystyrene.

The rnadrrmm toxicity index obtained f r m the combustion of

polystyrene was of the s a m e order as t h a t from wood. Thus, on

a

weight

b a s i s , the potential hazard due to toxic combustion products from

polystyrene is about the same as that fram wood.

REFERENCES

1. Tsuchiya,

Y.

andK. Surni. Thermal DecompositionProducts of

Polyvinyl Chloride,

J.

Applied Chem. Vol,

17,

p. 364

(1967).

2. Henderson,

Y.

and H,

W.

Haggard. Noxious G a s e s and the

Principles of R e a p h a t i o n Xnfluencing their Action. 2 12 p, (

19

27)

3 . Documentation of Threshold Limit Valtte s. American Conference of G o v e s m e n t a I Industrial Hygienists.

223

p.

(1966)

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Table 1A

Combustion Products of W h i t e Pine

Table

1B

Combustion Products of Polystyrene

- - - - - Sample Weight Img) 800 799 1007 949

i

1194 1197 1606 1600 Carbon Monoxide (d8) 0 . 24 0 . 2 5 0.35 0 . 3 6 0.45 0.44 0 . 4 1 0.43 I Carbon Dioxide

(g/g

0.86 0 . 8 4 0-90 0 . 9 2 0 . 5 5 0. 5 1 13.54 0.53

Re

sidue

(dg)

0.13 0 . 1 3 0.13 0.14

1

0.13

j

0.14

'

0.14 0.14 Sanaple Weight

( m g )

2 9 8 296 350 t 3 5 1 Carbon Monoxide

l d g 3

0 . 3 6 0 . 2 7 0-44 0.45 Carbon Dioxide 1 d g

3

2.36

2.94 406 498 497

R e

sidue ( g J g ) 0

1.44

1 . 2 1

I .

16

I . 09 1.03 I I 0.41 0 . 3 9 0.40 I 0.01

i

0 . 0 1 ; 0 . 0 1

!

0 . 0 2 0.02 460 1.94

1.43

1 . 5 4 0.46 599 604 0.0;

1

0 . 0 1 0 . 0 1 1 I _{0 . 3 5} 0-32

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Table 2A

Toxicity due ta Combustion Products

of White Pine

Sample Weight

Table 2B

Toxicity due to Combustion Products

of Polystyrene