Lethal effects of mattress fires

Publisher’s version / Version de l'éditeur:

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à [email protected].

Questions? Contact the NRC Publications Archive team at

[email protected]. If you wish to email the authors directly, please see the first page of the publication for their contact information.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

Research Paper (National Research Council of Canada. Division of Building

Research); no. DBR-RP-402, 1969-05-01

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.

https://nrc-publications.canada.ca/eng/copyright

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=cf5f7874-4a03-4a4e-83a6-71e967c8f988 https://publications-cnrc.canada.ca/fra/voir/objet/?id=cf5f7874-4a03-4a4e-83a6-71e967c8f988

NRC Publications Archive

Archives des publications du CNRC

This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.

https://doi.org/10.4224/40001536

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Lethal effects of mattress fires

Sumi, K.; Williams-Leir, G.

LETHAL E F F E C T S O F MATTRESS FIRES

by

K. Sumi*and G. Williams

-

L e i r *

ABSTRACT

F a t a l f i r e s a r e often a t t r i b u t e d to smoking in bed, and i t i s found in s o m e c a s e s t h a t the only m a t e r i a l consumed i s the v i c t i m ' s bedding. The m o d e of burning of cotton wadding in m a t t r e s s e s ignited in t h i s way i s unusual: t h e r e i s no f l a m e o r glow, but heat and smoke a r e r e l e a s e d .

In a s e r i e s of e x p e r i m e n t s with varying d e g r e e s of ventilation, the p r o d u c t s of combustion w e r e m e a s u r e d and the t e m p e r a t u r e r e c o r d e d .

On the b a s i s of published information on toxicity, e s t i m a t e s w e r e m a d e of the duration of human s u r v i v a l in e a c h c a s e ; t h i s i s found to be of the o r d e r of one hour e i t h e r in a s e a l e d r o o m o r one w h e r e t h e door i s opened 2 in.

S o m e s i m p l e p a s s i v e defence m e a s u r e s a g a i n s t this type of f i r e w e r e t e s t e d and found effective.

F o r a t e n - y e a r p e r i o d ending in 1963 the Division of Building R e - s e a r c h compiled s t a t i s t i c s on f i r e s in Ontario t h a t r e s u l t e d in d e a t h s . A f i r s t i n s t a l m e n t of t h e conclusions of this study, dealing with clothing and bedding f i r e s , h a s been published ( 1 ) and a f u t u r e p a p e r will give an account of building f i r e s . One observation f r o m this study i s that t h e r e a r e a f a i r n u m b e r of f a t a l f i r e s c a u s e d by smoking in bed, s a y 18 a y e a r i n Ontario (population 6 m i l l i o n ) , and t h a t often in s u c h c a s e s t h e only m a t e r i a l con- s u m e d by the f i r e i s the v i c t i m ' s bedding. In about half the c a s e s t h e v i c t i m i s o v e r a g e 50. I t s e e m e d d e s i r a b l e to know m o r e about this kind of f i r e , and to r e p r o d u c e e x p e r i m e n t a l l y the t r a i n of events t h a t follow ignition of a m a t t r e s s .

*

R e s e a r c h Officer, F i r e R e s e a r c h Section, Division of Building R e s e a r c h , National R e s e a r c h Council of Canada.

Recently the F i r e M a r s h a l s As sociation of North A m e r i c a pub- l i s h e d a resolution ( 2 ) dealing with the h a z a r d of f i r e to old people in n u r s i n g homes, stating that the only p r a c t i c a l r e m e d y i s a s p r i n k l e r

s y s t e m . F o r f i r e s in g e n e r a l this recommendation h a s m e r i t , but the Association apparently overlooked the m a t t r e s s f i r e that r e s u l t s f r o m smoking in bed. I t h a s yet to be e s t a b l i s h e d whether s p r i n k l e r s a r e a defence a g a i n s t this type of f i r e . To avoid m i s a p p r e h e n s i o n i t should b e s a i d that v e r y few of the O n t a r i o f a t a l bedding f i r e s took p l a c e in n u r s i n g h o m e s ; they w e r e m o s t l y in r e s i d e n c e s and roor-ning houses.

The e x p e r i m e n t s to be d e s c r i b e d c o n s i s t of two s e r i e s . In the f i r s t , m e t h o d s of protecting m a t t r e s s e s f r o m ignition by c i g a r e t t e s w e r e t r i e d . In the second, m a t t r e s s e s w e r e burned in a s i m u l a t e d bed- r o o m t o a s c e r t a i n the m e c h a n i s m that l e a d s to the d e a t h s of the occu- pants, and how quickly i t a c t s .

SERIES I

M a t e r i a l s

Old cotton m a t t r e s s c u t into 6-in. s q u a r e s Cotton sheeting, 3. 8 o z / s q yd

Polyethylene sheet, 0. 01 0 in. thick, c l e a r

Vinyl s h e e t (polyvinyl c h l o r i d e ) , 0. 008 in. thick, c l e a r Wool blanket s c r a p s , 13 o z / s q yd, used previously f o r

e x p e r i m e n t s on laundering

Wool blanket r e c e i v e d f r o m a hospital

M i x t u r e blanket: 75 p e r c e n t wool, 25 p e r c e n t orlon, 1 3 . 2 o z / s q yd Heavy cotton twill, s t a t e d to have been t r e a t e d with a c o m m e r c i a l

l a u n d e r a b l e f i r e r e t a r d a n t and then washed 12 t i m e s S i m i l a r but u n t r e a t e d heavy cotton twill

C i g a r e t t e s of v a r i o u s b r a n d s , with and without f i l t e r s .

All m a t e r i a l s w e r e conditioned t o e q u i l i b r i u m with 15 p e r c e n t RH and 7 3 ° F b e f o r e u s e .

Method

The m a t t r e s s s e c t i o n was placed on a n a s b e s t o s b o a r d in a f u m e cupboard. The f o r c e d ventilation was turned down to the m i n i m u m setting. Various combinations of the m a t e r i a l s w e r e placed on the m a t t r e s s , the c i g a r e t t e was lit, the cupboard window l o w e r e d t o a 1-in. opening, and the r e s u l t awaited.

T r i a l s w e r e m a d e t o examine the effect of l a y e r s of sheeting below and above the c i g a r e t t e . One l a y e r above p r e v e n t s th.e c i g a r e t t e f r o m rolling, and one l a y e r both below and above m a k e l i t t l e d i f f e r e n c e t o the s e v e r i t y of the t e s t . This a r r a n g e m e n t was consequently adopted a s s t a n d a r d .

R e s u l t s

The m a t t r e s s alone o r with the s t a n d a r d sheeting a r r a n g e m e n t ig -

nited consistently. Polyethylene softened, p e r f o r a t e d and s h r a n k away f r o m the hole, p e r m i t t i n g ignition of the m a t t r e s s . Vinyl sheeting p r e - vented ignition, a s did both s a m p l e s of woollen blanket. The o r l o n m i x - t u r e blanket a l s o p r e v e n t e d ignition, but the s c o r c h beneath i t was m o r e pronounced than t h a t beneath a p u r e wool blanket.

The t r e a t e d cotton twill p r e v e n t e d ignition, but the s i m i l a r un- t r e a t e d twill did not.

The d i f f e r e n c e s between kinds of c i g a r e t t e did not s e e m t o b e i m - p o r t a n t . Half a c i g a r e t t e was usually sufficient f o r ignition; in the event t h a t ignition did n o t r e s u l t , the e x p e r i m e n t was r e p e a t e d with a whole c i g a r e t t e .

The m o d e of burning of a m a t t r e s s ignited in this way i s i n t e r e s t - ing, and d i f f e r e n t f r o m t h a t of the m o r e common kinds of f i r e . A c o m - bustion f r o n t s p r e a d s out slowly in a l l d i r e c t i o n s through the m a t e r i a l . Ao f l a m e o r v i s i b l e glow a p p e a r s and the m a t e r i a l i s not e n t i r e l y con-

sumed, but p r o g r e s s i s shown by blackening of the m a t e r i a l and the r e - l e a s e of h e a t and s m o k e . M e a s u r e m e n t s show t h a t the combustion f r o n t p r o g r e s s e s a t a s p e e d of about 0.38 c m p e r minute.

SERIES

LI

E x p e r irnental Details

The e x p e r i m e n t s w e r e conducted in a s i m u l a t e d bedroom, which was a n 8-ft cube. A m a t t r e s s was placed on a s i m u l a t e d bed 2 f t above the f l o o r and a c i g a r e t t e lighted and placed horizontally on i t .

G a s e s w e r e s a m p l e d f o r a n a l y s i s f r o m a c o l l e c t o r positioned d i r e c t l y above the m a t t r e s s , 1 f t f r o m the ceiling. F i g u r e 1 i s a flow c h a r t of the a n a l y s i s a p p a r a t u s . The g a s e s w e r e pumped into a 5-gal r e s e r v o i r by m e a n s of a n a i r pump c a p a b l e of delivering a t a r a t e of 3 cfm, then s e n t through a p p r o p r i a t e d e v i c e s f o r a n a l y s i s f o r c a r b o n dioxide, c a r b o n monoxide, and oxygen. Water v a p o r and o t h e r condensable combustion p r o d u c t s w e r e r e - moved by m e a n s of f i l t e r s and t r a p s p r i o r to m e a s u r e m e n t . I n f r a r e d a b -

s o r p t i o n g a s a n a l y s e r s w e r e used f o r c a r b o n dioxide and c a r b o n monoxide d e t e r m i n a t i o n . The f u l l - s c a l e r a n g e s w e r e 0 t o 5 p e r c e n t C 0 2 and 0 to 0 . 3 p e r c e n t C O ; r e s p o n s e t i m e s w e r e 0 . 5 s e c to 90 p e r c e n t of f i n a l r e a d i n g and r a t e d a c c u r a c i e s w e r e f 1 p e r c e n t of f u l l s c a l e . The two i n s t r u m e n t s w e r e connected to potentiometer - type r e c o r d e r s . B e c a u s e of the l i m i t e d r a n g e of the CO a n a l y s e r , a dilution s y s t e m using a i r was s e t up by which c o n c e n t r a t i o n s up to 0 . 3 p e r c e n t could be d e t e r m i n e d . A c o n s t a n t t e m - p e r a t u r e bath was u s e d to e l i m i n a t e the e r r o r on the s a m p l e d g a s - a i r mixing r a t i o t h a t could b e c a u s e d by d i f f e r e n c e s in t e m p e r a t u r e . F i g u r e s 2 and 3 give the m e a s u r e d c o n c e n t r a t i o n s of c a r b o n monoxide and dioxide.

Oxygen c o n c e n t r a t i o n s w e r e d e t e r m i n e d by a d i r e c t r e a d i n g i n s t r u - m e n t of the magnetic susceptibility type. The i n s t r u m e n t had a f u l l - s c a l e r a n g e of 0 t o 25 p e r c e n t oxygen and a r a t e d a c c u r a c y of

+

1 p e r c e n t of f u l l s c a l e . F i g u r e 4 gives the oxygen c o n c e n t r a t i o n s . T h e t h r e e i n s t r u - m e n t s f o r g a s a n a l y s i s w e r e c a l i b r a t e d a g a i n s t a p p r o p r i a t e g a s m i x t u r e s of known composition.

T e m p e r a t u r e r e c o r d i n g s w e r e m a d e by m e a n s of a c h r o m e l - a l u m e l t h e r m o c o u p l e located n e a r the Ifgas collector^' and connected to a m i l l i v o l t p o t e n t i o m e t e r . Smoke m e a s u r e m e n t s w e r e m a d e ( e x c e p t f o r the f i r s t

e x p e r i m e n t ) by placing a s m o k e m e t e r under the bed. F i g u r e s 5 and 6 give t e m p e r a t u r e s and s m o k e d e n s i t i e s .

The s m o k e m e t e r was roughly the s a m e a s t h a t u s e d in the "St. L a w r e n c e B u r n s n ( 3 ) . A f u r t h e r m e a s u r e of s m o k e was provided by visual o b s e r v a t i o n of a 100-watt bulb on the f a r wall about 8 f t f r o m the window, with a switch outside.

The r a t e of p r o g r e s s of combustion was o b s e r v e d by drawing c i r c l e s on the m a t t r e s s b e f o r e e a c h e x p e r i m e n t and timing the s p r e a d t o e a c h c i r c l e a s long a s v i s i b i l i t y p e r m i t t e d . Cotton, s p r i n g filled m a t t r e s s e s w e r e used. After the f i r s t t r i a l i t was a p p a r e n t that one-half of a m a t t r e s s ( c u t t r a n s - v e r s e l y ) was sufficient. E x p e r i m e n t s 2 to 5 w e r e t h e r e f o r e conducted using

The e x p e r i m e n t a l conditions w e r e a s follows:

No. 1: T r i a l r u n with M a t t r e s s A.

No.2: M a t t r e s s B; the g a s e s that p a s s e d through the CO,, C O and 0, a n a l y s e r s w e r e r e t u r n e d t o the r o o m .

Ventilation was reduced t o a m i n i m u m by sealing any openings to the r o o m with a d h e s i v e tape.

No. 3: M a t t r e s s B; the g a s e s w e r e d i s c h a r g e d outside.

No.4: M a t t r e s s C; g a s e s d i s c h a r g e d outside. Door position was fixed t o provide a n opening of 1 in.

No. 5: M a t t r e s s C; g a s e s d i s c h a r g e d outside. Door position was fixed t o provide a n opening of 2 in.

In E x p e r i m e n t 2 the ventilation was m i n i m a l and a p p e a r s to have l i m i t e d the development of t h e f i r e . I n E x p e r i m e n t 3 t h e slight e x t r a venti- lation c a u s e d by sampling g a s and not r e t u r n i n g i t to t h e r o o m s e e m s t o have produced higher c o n c e n t r a t i o n s of CO, and CO. I n both, t h e r a t i o of CO to CO, r e m a i n e d roughly a t 1 t o 10. The CO production was in good a g r e e m e n t with what would be expected f r o m a f i r e s p r e a d i n g r a d i a l l y through a 3-in. l a y e r of c e l l u l o s e of the o b s e r v e d density (0. 065 g m / c m 3 ) a t the o b s e r v e d r a t e (0. 38 c m / m i n ) . M o s t of the heat of combustion was l o s t by convection t o t h e walls.

E x p e r i m e n t s 4 and 5, with t h e door opening fixed a t 1 and 2 in. produced m o r e vigorous combustion and higher t e m p e r a t u r e s but lower concentrations of combustion products. To under stand t h i s i t should be r e m e m b e r e d that l o s s of g a s e s i n E x p e r i m e n t s 2 and 3 was negligible, but that heat l o s s f r o m the g a s e s in the r o o m was s u b s t a n t i a l in a l l e x p e r i - m e n t s .

The c o r r e l a t i o n between visibility of the l a m p and s m o k e density be- low i t was poor: with the door c l o s e d a f a i r l y homogeneous s m o k e m i x t u r e was gradually attained by convection; with i t open the inflow was f a s t enough t o m a i n t a i n c l e a r a i r below t h e bed.

In the development of t h e s e m a t t r e s s f i r e s two r e g i m e s m a y b e distinguished:

I llSmoulderingn: Radius of burning a r e a i n c r e a s i n g l i n e a r l y with time: s y s t e m controlled by r a t e of propagation through wadding.

I 2 "Free-burning#': R a t e of i n c r e a s e p r o p o r t i o n a l t o s i z e of f i r e . E x p e r i m e n t s 2 and 3 never went beyond Regime I. No. 2 reached a l i m i t , p r e s u m a b l y i m p o s e d by a i r supply.

E x p e r i m e n t s 4 and 5 switched to R e g i m e

_II

between 65 and 80 m i n when the t e m p e r a t u r e a t the thermocouple was 40 to 45 " C. In E x p e r i m e n t 5, f l a m e s w e r e detected a t 84 m i n ( 1 10" C), and m a y have been p r e s e n t throughout Regime I1 s i n c e v i s u a l observation was handi- capped by the smoke. The f i r e s w e r e extinguished b e f o r e they w e r e l i m i t e d by t h e i r a i r o r fuel supplies.

Survival

I t i s i m p o r t a n t t o know how long anyone could live under the con- ditions obtaining in the t e s t r o o m and what f a c t o r s would eventually b e r e s p o n s i b l e f o r h i s death.

To e s t i m a t e d u r a t i o n of s u r v i v a l i t i s n e c e s s a r y to know the

quantities of the toxic f a c t o r s p r e s e n t , and to know a l s o how t h e s e f a c t o r s s e p a r a t e l y and together influence s u r v i v a l . The quantities w e r e m e a s u r e d by the methods d e s c r i b e d above, and information on s u r v i v a l f r o m the l i t e r a t u r e i s d i s c u s s e d in Appendix A. I t m u s t be a p p r e c i a t e d t h a t p r o d u c t s of combustion other than t h o s e m e a s u r e d w e r e p r e s e n t and m i g h t well r e d u c e a v i c t i m ' s s u r v i v a l p e r i o d .

Lf t h e equation f o r this i s c o r r e c t , then with the c o n c e n t r a t i o n s of c a r b o n monoxide and c a r b o n dioxide found in E x p e r i m e n t 3 t h e l e t h a l con- dition would be r e a c h e d in 67 min. The s a m e condition would b e r e a c h e d in 73 m i n without the C0,but with the s a m e c o n c e n t r a t i o n s of CO.

This i s the situation with no ventilation. At the end of t h i s t i m e the t e m p e r a t u r e r i s e would be no m o r e than about 15 C e l s i u s d e g r e e s , s o t h a t h e a t would not c o n t r i b u t e m u c h to t h e l e t h a l effect, nor would i t open a

s p r i n k l e r head. Neither would oxygen deficiency b e s e r i o u s .

With 2 in. of door opening, exposure t o the reduced c o n c e n t r a t i o n s of c a r b o n monoxide would not b e l e t h a l until 86 min. When CO, and h e a t a r e allowed f o r , this b e c o m e s 80 min. All t h e s e e s t i m a t e s a r e upper l i m i t s and would b e a c c u r a t e only if t h e r e w e r e no s y n e r g i s m ; it i s unlikely t h a t

s y n e r g i s m i s in f a c t a b s e n t .

F i g u r e 7 shows the accumulating effect of t h e toxic influences, a s indicated by Equation 4 of Appendix A.

To s u m m a r i z e t h i s speculation on toxicity, i f with no ventilation a v i c t i m ' s e n d u r a n c e i s exhausted in about 70 min, and with a door a j a r by 2 in. in about 80 min, i t m a y be concluded t h a t the ventilation m a k e s only a n u n i m p o r t a n t d i f f e r e n c e to a v i c t i m ' s p e r i o d of s u r v i v a l .

At t i m e 70 min, t e m p e r a t u r e s a d j a c e n t t o the s p r i n k l e r head had r i s e n f r o m t h e i r i n i t i a l v a l u e s by 11, 17, 16 and 35 C e l s i u s d e g r e e s in E x p e r i - m e n t s 2 to 5. Thus if they had e a c h s t a r t e d f r o m 20" C, and given that the lowest s t a n d a r d rating f o r s p r i n k l e r s i s 1 3 5 ° F o r 5 7 ° C ( 4 ) , i t i s c l e a r t h a t a s p r i n k l e r would o p e r a t e too l a t e t o s a v e l i f e in this kind of f i r e .

CONCLUSIONS

Anyone who ignites a m a t t r e s s and does not wake within 70 to 80 m i n will probably not s u r v i v e ; h i s death will have been due p r i m a r i l y t o the effects of c a r b o n monoxide, but p a r t l y to t h o s e of c a r b o n dioxide and heat. If i t i s not f e a s i b l e to d i s c o u r a g e o r p r e v e n t people f r o m smoking i n bed, a n effective defence m e a s u r e i s to p l a c e a l a y e r of p r o t e c t i v e

m a t e r i a l between s h e e t s and m a t t r e s s . Among effective m a t e r i a l s a r e woollen blankets, c e r t a i n types of p l a s t i c sheeting, cotton cloth t r e a t e d with a c o m -

m e r c i a l l a u n d e r a b l e f i r e r e t a r d a n t , and the m a t e r i a l s examined by Hammack ( 5 ) . T h e s e will not p r e v e n t c h a r r i n g d a m a g e to a m a t t r e s s , but should p r e v e n t

ignition. Which i s m o s t s u i t a b l e will b e d e t e r m i n e d by c o n s i d e r a t i o n s other than t h e i r f i r e p r o p e r t i e s .

Automatic s p r i n k l e r s , though well-established a s a defence a g a i n s t m a n y o t h e r types of f i r e , will not alone s e r v e to defend l i f e a g a i n s t m a t t r e s s f i r e s .

R E F E R E N C E S

1. W i l l i a m s

-

L e i r , G. Deaths F r o m Clothing and Bedding F i r e s

.

Can. J. P u b l i c Health, Oct. 19 67.

2. R e s o l u t i o n of F i r e M a r s h a l s A s s o c i a t i o n of N o r t h A m e r i c a , 17 M a y 1965; F i r e J . ,

2,

24, Sept. 65.

3. S h o r t e r , G. W. and o t h e r s . The St. L a w r e n c e Burns. National F i r e P r o t e c t i o n A s s o c i a t i o n Q u a r t e r l y ,

-

53, 4, Apr. 1960, p. 300. 4. National F i r e P r o t e c t i o n As s o c i a t i o n S t a n d a r d f o r t h e I n s t a l l a t i o n of S p r i n k l e r S y s t e m s No. 13, p. 84, 1965. 5. H a m m a c k , J . M . C i g a r e t t e Ignition of Bedding. F i r e J.

-

59, 9 , M a y 65. T h i s p a p e r i s a c o n t r i b u t i o n f r o m t h e Division of Building R e s e a r c h , N a t i o n a l R e s e a r c h Council of Canada and is p u b l i s h e d with t h e a p p r o v a l of t h e D i r e c t o r of t h e Division.

EXHAUST OR R E TURN TO ROOM E X H A U S T

OXYGEN

50

_{C C I M I N}

OR

a

A N A L Y Z E R

>

_{TO ROOM} RETURN

CONSTANT TEMP

B A T H

E X H A U S T OR

T I M E , M I N U T E S

( t 2

s c a l e )

F I G U R E 2

C A R B O N M O N O X I DE C O N C E N T R A T I O N

60

80

1 0 0

T I

ME, M I N U T E S

( t 2

s c a l e )

F I G U R E

3

C A R B O N D l O X 1 D E C O N C E N T R A T I O N

4 0

60

80

1 0 0

1 2 0

T I

ME.

M I N U T E S ( t 2 s c a l e )

F I G U R E 4

O X Y G E N C O N C E N T R A T I O N

6 0

80

100

T I M E .

M I N U T E S

( t 2 s c a l e )

F I G U R E 5

T E M P E R A T U R E R I S E , N E A R C E I L I N G

4 0

6 0

80

100

1 2 0

T I M E , M I N U T E S

( t 2 s c a l e )

F I G U R E 6

S M O K E D E N S I T Y N E A R F L O O R

( L a m p a b o v e b e d v i s i b l e u n t i l

e

₎

1 0

2

0

30

4 0

50

60

70

80

90

M I N U T E S

F I G U R E 7

T O X I C E F F E C T A N D I T S C O M P O N E N T S , N U M E R I C A L L Y

APPENDIX _A

The d u r a t i o n of human s u r v i v a l under e x t r e m e l y a d v e r s e con- ditions i s r e l a t e d to the s e v e r i t y of those conditions; the m o r e s e v e r e the conditions the s h o r t e r the s u r v i v a l . Quantitative d a t a a r e s c a n t y and i t i s not t o be expected that any p r e c i s e r e l a t i o n c a n be found.

The c h e m i c a l asphyxiant, c a r b o n monoxide, a s f a r a s i s known, i s the w o r s t single h a z a r d of t h o s e to which the v i c t i m i s exposed. O t h e r s include heat, c a r b o n dioxide, oxygen deficiency, and the effects of c e r t a i n p r o d u c t s of incomplete combustion such a s aldehydes. Henderson and Haggard (A- 1) s t a t e that a dangerous condition e x i s t s when the p r o -

duct of concentration of CO in p e r c e n t and e x p o s u r e t i m e in m i n u t e s equals 9 . I t s e e m s r e a s o n a b l e to t a k e half this exposure a s sufficient t o p r e v e n t the v i c t i m f r o m escaping in t i m e . This may be g e n e r a l i z e d f o r varying con- c e n t r a t i o n s a s follows (A-2):

whe.re K i s the concentration of c a r b o n monoxide ( p e r c e n t )

C O

T i s the m a x i m u m t i m e a v a i l a b l e f o r e s c a p e ( m i n u t e s )

Up t o a c e r t a i n concentration of c a r b o n dioxide, the body i s u n h a r m e d b e c a u s e i t can maintain n o r m a l conditions in the lungs by a n automatic in- c r e a s e in breathing. S i m i l a r l y the body a d j u s t s t o h e a t by sweating. P r e - sumably any e x c e s s over the t o l e r a b l e level c a n be i n t e g r a t e d in the s a m e way a s with c a r b o n monoxide, f o r which the t o l e r a b l e l e v e l i s v e r y low.

P r y o r and Yuill ( A - 3 ) have r e c e n t l y collected the data shown in F i g u r e s A- 1 and A-2; t h e s e m a k e i t p o s s i b l e to a s s i g n n u m e r i c a l values to the c o n s t a n t s in equations f o r s u r v i v a l t i m e analogous to Equation ( 1 ) : F o r c a r b o n dioxide (A-4, A-5),

S i m i l a r l y f o r the t e m p e r a t u r e of s t i l l d r y a i r , in C e l s i u s d e g r e e s (A-6, A-7):

Lf

two o r m o r e i n s u l t s t o t h e body a r e o f f e r e d t o g e t h e r , w e m a y s a y t h e y a r e a d d i t i v e if: w h e r e X i s t h e m e a s u r e of t h e k - t h i n s u l t c bk a r e c o n s t a n t s . k

'

T h i s p r o v i d e s a m e a n s of e s t i m a t i n g s u r v i v a l t i m e i f i t c a n b e a s s u m e d t h a t t h e e f f e c t s of h e a t a n d toxic g a s e s a r e a d d i t i v e . In p r a c t i c e , s y n e r g i s m p r o b a b l y i s p r e s e n t i n m a n y c a s e s ; f o r e x a m p l e , t h e p r e s e n c e of CO,, by i n c r e a s i n g r e s p i r a t i o n , w i l l a c c e l e r a t e t h e u p t a k e of a n y s u b s t a n c e w i t h h i g h a f f i n i t y f o r hemoglobin, s u c h a s CO, t h a t m a y b e p r e s e n t . R a s b a s h r e c e n t l y pointed out ( A - 8 ) , t h a t t h i s e f f e c t should b e c a l c u l a b l e f o r CO, a n d CO t o g e t h e r :

R E F E R E N C E S

A - 1 H e n d e r s o n , Y. a n d H. W. H a g g a r d , Noxious G a s e s a n d t h e P r i n c i p l e s of R e s p i r a t i o n Influencing T h e i r Action, 2nd ed.

,

R e i n h o l d 1943, p . 168. A-2 Minchin, L. T. M i l d C a r b o n Monoxide P o i s o n i n g a s a n I n d u s t r i a l H a z a r d .

I n d u s t r i a l C h e m i s t , 30, No. 355, Aug. 1954, p . 3 8 1 - 5 .

A-3 P r y o r , A. J . a n d C. H. Yuill. M a s s F i r e L i f e H a z a r d . SWRI P r o j e c t 03-1726, C o n t r a c t N228 (62479) 68665. OCD W o r k U n i t 2537A.

A - 4 Roth, E. M. S p a c e C a b i n A t m o s p h e r e , P a r t 2, F i r e and B l a s t H a z a r d s . NASA-SP48, 19 64.

A - 5 P e s m a n , G. J . A p p r a i s a l of H a z a r d s t o H u m a n S u r v i v a l i n A i r c r a f t C r a s h F i r e s . NACA T e c h . Note 2996, S e p t . 53.

A - 6 B u e t t n e r , K o n r a d . H e a t T r a n s f e r a n d S a f e E x p o s u r e T i m e f o r M a n in E x t r e m e T h e r m a l E n v i r o n m e n t . ASME p a p e r 57-SA-20. J u n e 1957.

A-7 Blockley, W. V. a n d C. L. T a y l o r . S t u d i e s of H u m a n T o l e r a n c e

f o r E x t r e m e H e a t . R e p o r t NCREXD-69 6- 113A, USAF, W r i g h t - P a t t e r s o n A F B , Ohio,Nov. 1948.

F I G U R E A - 1

H U M A N S U R V I V A L I N U N N A T U R A L A T M O S P H E R E S

( R e f : P r y o r &

Y u i l l )

BR 4 0 6 5 - 8

F I G U R E A - 2

H U M A N S U R V I V A L I N S T I L L D R Y H E A T

( R e f : P r y o r & Y u i l l )

BR 4 0 6 5 - 9