NEW HAMPSHIRE, ST ATE BOARD OF HEALTH, 
Travis P. Burroughs, M. D., Secretary 
Control of the Health Hazards 
Incidental to Spray Painting 
DIVISION OF INDUSTRIAL HYGIENE 
Frederick J. Vintinner, Director 
Concord, New Hampshire 
1941 CONTROL OF THE HEALTH HAZARDS INCIDENTAL 
TO SPRAY PAINTING 
Changes in the painting industry in the last twenty years 
have affected both materials and methods of application. 
Chemists are constantly developing new substances, and in 
particular, the cellulose lacquers and synthetic resins, which 
have taken the place of paint for many purposes. Faster 
methods of application have been developed, such as spray- 
ing or dipping tanks, and these are rapidly eliminating the 
old hand brush method. The introduction of the spray gun 
has brought many changes in the painters’ trade. Formerly, 
brush work was considered as skilled labor but any man with 
ordinary intelligence can learn to spray in a short time. Con- 
sequently the use of spray guns in many instances has fallen 
into the hands of workers who admittedly have little or no 
knowledge concerning the harmful ingredients of the materi- 
als used. The use of these new substances and new methods 
of application has and will continue to increase the possible 
health hazards in this industry. 
The extent of the hazards in connection with spray- 
painting or spray-coating work depends upon the nature of 
the ingredients of the coating used and upon the proper use 
of precautionary measures. Unfortunately, the toxicity of 
these new compounds may be entirely or practically unknown 
and a constant vigilance and an increasing use of proper 
safeguards are essential to health protection. 
In general the danger from coatings lies not in the solid 
part but in the liquid portion or vehicle—solvent. The use 
of lead pigment has been displaced to a large extent by 
other materials which are for the most part harmless. Thus 
the dangers from the highly toxic lead compounds are grad- 
ually giving away to much less harmful substances. Lacquer 
solids, with the exception of a few types of pigments, are 
usually quite free from harmful effects on the worker who 
breathes them. 
The toxicity of the liquid portion depends largely on the 
evaporation of the volatile liquid fraction, because the more 
volatile the liquid, the more quickly is the air in the work- 
room contaminated. A quick drying thinner is therefore 
always to be regarded with suspicion. The degree of harm- 
fulness depends upon the particular toxic property of the 
solvent upon the human body. While the tendency in recent 
years has been to eliminate the more dangerous of the sol- 
vents and the present use of coatings is far less dangerous 
than it was a few years ago, no solvent can be classed as 
being inert. It is often heard that “your nose knows,” but this saying 
does not apply to solvent vapors. Benzol does not have as 
penetrating an odor as amyl acetate but it is considerably 
more toxic. Solvent vapors in general do not possess prop- 
erties of irritation to nose and throat but rather the odors 
are pleasant, which means absorption goes unnoticed and the 
worker does not realize the air he is breathing is injurious 
to his health. 
Solvents and diluents may be divided into several groups1 
according to their chemical structures, such as: (1) Ester 
Solvents. These usually consist of methyl, ethyl, propyl, butyl 
and amyl acetates. (2) Ketones. These are widely used 
and their action is similar to the alkyl esters. (3) Ethers. 
These are usually the mono-methyl, mono-ethyl and mono- 
butyl ethers of ethylene glycol. (4) Hydrocarbons. Those 
in use are usually benzine (petroleum naptha), benzol (ben- 
zene), toluol, xylol and mixtures of these and some of the 
higher aromatic hydrocarbons. (5) Alcohols. Usually 
methyl, ethyl, propyl, butyl and amyl alcohols, in addition 
to the cyclohexanols, are used in lacquers. It should be 
remembered that the toxicities of the volatile lacquer com- 
ponents are not necessarily dependent upon the harmfulness 
of each ingredient. Paints and lacquers contain mixtures of 
organic solvents and the toxicity of the mixtures of these 
materials in the majority of cases is not known. It should 
be remembered that any volatile organic material will pro- 
duce narcosis or asphyxia if present in sufficiently high con- 
centrations. Some of the solvents, such as benzol, toluol, 
butyl alcohol and others, are known to have a serious dam- 
aging effect upon the blood. 
Control of the Health Hazard 
Of course the most efficient way to protect the health 
of the painter is to select coatings that are free from poison- 
ous constituents, but this is an impossibility, since there are 
over one thousand paint manufacturing plants in the United 
States and these use so many and varying formulae, includ- 
ing many new materials, the harmfulness of which is not 
known, that research laboratories could devote all their time 
to studying the toxicity of these materials and products of 
the paint industry and still be unable to keep up to date. 
Much has been accomplished in recent years in the control 
of the painting hazard by the elimination of certain toxic 
substances or by reducing their concentrations in the lacquer. 
It is known that benzol and methyl alcohol have been for 
the most part eliminated from lacquer solvents. Continued 
research will make possible the avoidance of the use of these 
more toxic substances and still retain the desirable properties 
and characteristics of the coatings. Until these paints and 
lacquers have reached a state where they are non-toxic to 
the employee, we must resort to other protective measures. 
Since the usual route of the absorption of volatile sub- 
stances is through the lungs, the important item in control is to minimize the concentration of vapors in the atmosphere 
breathed by the worker. If the concentration of solvent 
vapor is kept below a certain limit specific for each solvent, 
then it may be considered that the condition is non-injurious. 
During spraying operations, the paint or lacquer is 
broken up into fine droplets or mist. A certain amount of 
the mist contaminates the working atmosphere and must not 
be breathed in the amounts given off by spray painting. 
This air contamination, as well as being a hazard to health, 
is also a potential explosive and fire hazard. Spray-painting 
operations should be conducted within an enclosure or booth 
which is constantly ventilated for the removal of the fumes. 
Figures 1 and 2 illustrate a typical design of spray booths. 
FIGURE I 
The size and depth of the booth are dependent upon 
the magnitude and shape of the objects to be sprayed. Like- 
wise the position of the operator is important in determining 
the size of the booth. If the operator remains outside as 
with a bench booth, then the dimensions are made as small 
as possible to permit the work. The depth should be greater 
than the cross sectional area in order to permit operation of 
the spray gun well within the booth. This will allow for 
exhausting the mist before it can escape into the air in the 
workroom. Air velocity should not be less than 100 f.p.m. and in cases where benzol, lead or other highly toxic sub- 
stances are present, the air velocity should not be less than 
150 f.p.m. 
FIGURE 2 
If the operator works within the booth the air flow 
should be so directed that the mist is eliminated in his breath- 
ing zone. For this purpose the direction of the air flow 
should be horizontal through the booth at a rate such as to 
reduce the vapor concentration to a safe level. This rate of 
ventilation is determined from the product of the specified 
air velocity and the cross sectional area of the booth. Air 
velocity should not be less than 100 f.p.m. at breathing zone 
and in case of highly toxic materials should not be less than 
150 f.p.m. Operating cost for power and heat may be re- 
duced by installation of baffles or fire stops which reduce 
the operating opening. If the operator stands in the booth 
opening, the velocity through this opening is the controlling 
factor and the rate of ventilation is the product of the air 
velocity and the free open area. 
Hatch and Northrup2 recommend the following table for 
installation of baffles: 
BAFFLES 
NUMBER AND SPACING 
Spacing: Inches 
Dimensions: Ft. 
Number of 
Panels 
Between 
Top and 
Bottom 
(A x B) 
Panels (E) 
Side (F) 
(G) 
3x3 
1 
* 
* 
* 
6 Vz x 4 
3 
4 
6 
12 
6V2 x 6 
4 
4 
6 
12 
6V2 x 8 
6 
4 
10 
12 
6V2 x 10 
9 
6 
10 
18 
9 x 12 
9 
8 
12 
18 
12 x 14 
12 
8 
18 
24 
* For booths 3' 
x 3' and smaller: 1 panel 6" larger than fan diameter The air outlet from the spray booth should be direct to 
the outside, either through a wall or discharged at some point 
above the roof. Precautions should be taken in the location 
of the point of discharge so that the solvent vapors do not 
enter occupied rooms through open windows and doors. 
The construction of piping should follow modern engi- 
neering standards, and cleanout openings should be installed 
near the fan and at bends. 
Fresh-air inlets for the booths should be free from harm- 
ful materials and should be clean, so that the painted sur- 
faces will not be contaminated. The air should be heated 
to prevent rapid cooling of the operation during cool weather. 
Air inlets should be arranged so as to prevent any short 
circuiting of the air currents in the booth. 
In cases where it is impracticable to conduct spray paint- 
ing operations in ventilated booths or rooms, as encountered 
in the spraying of large objects, the vapors can be controlled 
by means of local exhaust ventilation through floor-type grille 
openings. These grilles are essentially exhaust hoods in a 
face-up position in which the floor itself acts as a flange. 
The quantity of air required can be computed from the fol- 
lowing formula: 
Q = V (10X2 + A) 
Q = Cubic feet per minute 
V = Controlling air velocity (f.p.m.) 
X = Distance from source to face of hood (feet) 
A = Area of hood opening (sq. ft.) 
For ordinary spray painting work, V can be assumed to 
be 75 f.p.m. and X to be 3 feet. 
For fire prevention the following items should be con- 
sidered; (1) All parts of the booth should be constructed 
of fire resistant material, (2) all electric lights inside the 
booth should be of the vapor proof type and no motor, 
switches or other sparking devices should be located inside 
the booth, (3) booths should be kept free from accumulations 
of material and should be cleaned periodically, and (4) all 
materials should be mixed and stored in a fireproof room. 
After the materials have been sprayed they are usually 
stored nearby the operation to dry. The vapors given off 
during this drying process should be exhausted either by 
means of a well-ventilated room or by local exhaust ventila- 
tion as used for exhaust tables or grille openings. 
Personal Protective Respiratory Equipment 
The use of positive pressure respirators, if properly de- 
signed and operated, will furnish adequate safeguard against 
inhalation of paint fumes. These require the accompanying 
air pump and hose line through which fresh air is delivered 
into the respirator. However, this type of respirator with 
its hose attachment is not entirely satisfactory for all pur- 
poses, particularly if the painter must travel around con- siderably or work on scaffolds or walk planks. Where the 
concentration of paint or lacquer vapors is particularly high, 
the positive pressure hooded masks have been found to be 
satisfactory. 
While there are available commercially several types of 
filter respirators, it should be remembered that with the ex- 
ception of the specially approved respirators, they are of little 
or no value for protection against organic vapors and mists. 
Dust respirators do not give protection in spray painting. 
In respect to the chemical cartridge respirators, these are 
provided with special chemical filters designed for specific 
vapors, and with their use particular attention should be 
given to the replacement of the chemical filters at such times 
when they become inefficient in filtering out the solvent va- 
pors. The United States Bureau of Mines has approved a 
number of respiratory protective devices which have satisfac- 
torily passed tests for effectiveness in protecting the wearer 
against dust, fumes, mists, and gases. A list of these approved 
devices may be obtained upon request to this department. 
Paint Dermatitis 
Solvents may be absorbed directly through the skin. 
Contact with the skin may lead not only to systemic poison- 
ing but also to irritation of the skin itself. The dermatitis 
is due to allergy to the varied ingredients, to the solvent ac- 
tion of the volatile substances or to the practice of painters 
washing with gasoline or other solvents. Control of paint 
dermatitis can be accomplished by means of protective cloth- 
ing, such as overalls, caps, gloves, through the use of pro- 
tective skin creams, such as lanolin, vaseline or other water 
soluble creams, and by preventing the use of solvents for 
washing. 
The deciding factors as to what type of control is to be 
used always must be the nature and amount of vapors to 
be removed and controlled. The Industrial Hygiene Division 
of the New Hampshire State Board of Health is prepared to 
aid the industries of New Hampshire by determining whether 
a hazard to health exists and by recommending the most in- 
expensive and practical control measures. 
References 
1 Hazards Incidental to Industrial Uses of Nitrocellulose Lacquers. Indust. 
Bull., New York Dept, of Labor, 17, 314 (July 1938) Burk, William J., 
and Goldwater, Leonard J. 
2 Hatch, Theodore, Northrup, Robert B. Exhaust Booth Designed to In- 
sure Health and Safety in Spray Painting. Indust. Bull., New York Dept, 
of Labor, 18, Sept. 1939. 
I. H. C-15 
1640