UNITED STATES IPARTMENT OF OMMERCE

UBLICATION

t»tor c

NBS TECHNICAL NOTE 711

'"•wis o'

U.S.

IEPARTMENT

OF

COMMERCE

IOO

no. 11/

I? 72
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and

technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measure- ment system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4). technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Center for Computer Sciences and

Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates

that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Measurement Services and the following divisions: Applied Mathematics—Electricity—Heat—Mechanics—Optical Physics—Linac

Radiation2—Nuclear Radiation2—Applied Radiation2—Quantum Electronics3—

Electromagnetics3—Time and Frequency3—Laboratory Astrophysics3—Cryogenics3

. THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research lead- ing to improved methods of measurement, standards, and data on the properties of

well-characterized materials needed by industry, commerce, educational institutions, and

Government; provides advisory and research services to other Government agencies; and develops, produces, and distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials and the following divisions: Analytical Chemistry—Polymers—Metallurgy—Inorganic Materials—Reactor

Radiation—Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to pro- mote the use of available technology and to facilitate technological innovation in industry and Government; cooperates with public and private organizations leading to the development of technological standards (including mandatory safety standards), codes and methods of test; and provides technical advice and services to Government agencies upon request. The Institute also monitors NBS engineering standards activities and

provides liaison between NBS and national and international engineering standards

bodies. The Institute consists of the following divisions and offices: Engineering Standards Services—Weights and Measures—Invention and

Innovation—Product Evaluation Technology—Building Research—Electronic Technology—Technical Analysis—Measurement Engineering—Office of Fire Programs.

THE CENTER FOR COMPUTER SCIENCES AND TECHNOLOGY conducts re- search and provides technical services designed to aid Government agencies in improving cost effectiveness in the conduct of their programs through the selection, acquisition, and effective utilization of automatic data processing equipment; and serves as the principal focus within the executive branch for the development of Federal standards for automatic data processing equipment, techniques, and computer languages. The Center

consists of the following offices and divisions: Information Processing Standards—Computer Information—Computer Services —Systems Development—Information Processing Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and accessibility of scientific information generated within NBS and other agencies of

the Federal Government; promotes the development of the National Standard Reference Data System and a system of information analysis centers dealing with the broader

aspects of the National Measurement System; provides appropriate services to ensure

that the NBS staff has optimum accessibility to the scientific information of the world, and directs the public information activities of the Bureau. The Office consists of the following organizational units: Office of Standard Reference Data—Office of Technical Information and

Publications—Library—Office of International Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

2 Part of the Center for Radiation Research.

3 Located at Boulder, Colorado 80302.
1L BUREAU OF STA^D*: FEB 71972

UNITED STATES DEPARTMENT OF COMMERCE

QC/lO£) Maurice H. Stans, Secretary

US NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director U>. Til -— i>r;|]N!CAI. :

: NBS

ISSUED JANUARY 1972

Not. Bur. Stand. (U.S.), Tech. Note 7 1 1, 77 pages (Jan. 1972) CODEN: NBTNAE

Measures for Air Quality, Annual Report—FY 1971

J. R. McNesby and R. Byerly, Jr.

Institute for Materials Research

National Bureau of Standards

Washington, D.C. 20234

s"»r.„ o< *

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C, 20402. (Order by SD Catalog No. C 13.46:711). Price 70 cents.
Dr. L. M. Branscomb, Director of NBS,

has just presented a sulfur dioxide

permeation tube to Dr. John Middleton,

Commissioner of the National Air

Pollution Control Administration.
TABLE OF CONTENTS

Introduction 1 Executive Summary 6

Major MAQ- Projects

Optical Measurement of Particle Size

Distributions 8

Determination of the Size Distribution of

Airborne Particulate Matter in Real Time

by a Light Scattering Method 13

Separations and Identification of Carcinogens

Adsorbed on Particles 16

Particulate Reference Material 20

Identification and Structure of Crystalline

Components of Particulate Matter in Air

Pollution Samples 22

Indoor Air Pollution 24

Electron Energy Loss Spectroscopy of Pollutants — 26

Molecular Complexes of Gaseous Pollutants 2?

Frictional Degradation of Rubber 33

Modulated Infrared Laser Absorption Techniques

for Atmospheric Pollutant Measurements 37

Atomic Emission Detector 39

The Role of the Lowest Excited Metastable State

of SO2 in the Photochemical Production of

Air Pollutants ' 41

Collection and Evaluation of Physico-Chemical

Data for Air Pollutants 46

Air Pollution Chemistry 48
Minor MAQ Projects

NBS Air Sampling Station 51

Far IR Carbon Monoxide Monitor 3

3

Chemical Composition of Polluted Air 56

Field Emission Spectroscopy 59

Identification of Free Radicals in Smog

Mechanisms 61

Calibration Standards Via Pyrolysis 63

Fluorescence Detector for SOp 64

Nitric Oxide SRM Development 65

EPA Projects

Instrumentation Assistance to the National Air Pollution

Control Administration 67

The Sulfur Dioxide Permeation Tube 68

The Nitrogen Dioxide Permeation Tube 70

Ozone 71

Emissions of Rubber from Auto Tires 72

List of Publications, FY 1971 73
- 1 -

MEASURES FOR AIR QUALITY

Annual Report

FY 1971

The Measures for Air Quality Program has now completed

the first year of its activity. The program, operating formally

out of the Institute for Materials Researches a NBS-wide

research effort whose purpose Is to advance air pollution

measurement science. The MAQ office operates with a staff

of three, the manager, his deputy, and one secretary. An

important part of the program is to avail the staff of

the opportunity to hear lectures by air pollution experts

and to be kept abreast of important developments in problem

areas of air pollution measurement. To this end, a number of MAQ seminars were held as indicated in Table 1 and a newsletter, the MAQROSCOPE, was produced approximately

bimonthly

.

It is important that the MAQ effort be responsive to

the needs of EPA and of American industry. The MAQ officers,

therefore, made a special effort during the past year to increase

our contact with EPA people responsible for implementation

of the EPA measurement mission and with the industrial sector.
- 2 -

TABLE 1

MAQ Seminars

J. R. McNesby, "Explanation of the MAQ Program and Other

Organizational Details." September 16, 1970.

S. N. Milford, "Dispersion of Air Pollutants in Large Urban

Areas." September 23, 1970.

W. D. Lee, "Environmental Quality Control Functions of the

Bureau of Domestic Commerce." September 30, 1970.

Solomon Zaromb , "Lidar Spectroscopy in the 265-295 nm Wavelength Range." October 14, 1970.

Walter Braun, "Two Recent Optical Techniques Applicable to

Detection of Trace Amounts of Air Pollutants."

November 23, 1970.

Julian Heicklen, "The Photochemistry of Urban Atmospheres."

November 17, 1970.

L. Kreuzer, "Ultrasensitive Infrared Spectroscopy Techniques

for Gas Detection." November 2, 1970.

Robert L. Byer, "Optical Methods to Determine the Amount of

Gaseous Pollutants in the Atmosphere." December 9, 1970.

James Hodgeson, "Chemiluminescence Applied to Air Pollution

Monitoring." February 10, 1971.

Pat McCormick, "The Application of Laser Radar to Measurement

of Air Pollution in the Earth's Atmosphere." March 10,

1971.

George Gordon, "Purpose and Operation of the National

Industrial Pollution Control Council." May 11, 1971.
- 3 -

The interest of EPA in NBS immediately prior to the MAQ

rogram was apparent in their support of the development

f calibrated permeation tubes for S0

? and N0? as well as

f a calibrated photochemical ozone generator. The

elationship between NBS and EPA has become more broadly

ased during the past year with the increased emphasis at

IBS on development of measurement methods

The MAQ program extended its industrial contact by

rranging the placement of an ASTM Industrial Research

ssociate in residence at NBS. Dr. Richard Johns, the IRA

rom ASTMjis conducting research on permeation tube

:alibration devices in conjunction with his Project

threshold activity. MAQ officers have established close

:ontact with the automobile industry through the Air

'ollution Research Advisory Committee of the auto industry's

;oordinating Research Council. Additional industrial

elationships have been established with a number of

ndustrial associations and individual industrial

:orporations . A large number of letters were sent to air

)ollution-connected industries inviting them to participate

n our program on an industrial research associate basis.

)nly ASTM has accepted this invitation.

Foreign participation has been solicited through a lumber of science attaches at U.S. embassies. Dr. Billon

Trom France is on board as the FY 72 year begins.
- 4 -

The research effort may be divided roughly into three

funding categories. Major Projects in which at least $5K was provided by the MAQ Office, Minor Projects receiving a few hundred to a few thousand dollars in RTS support, and EP; Projects. The progress reports that form the body of this

first annual MAQ report are categorized in this way. It is

noteworthy that some of those in the Minor Projects category

will be (by virtue of the new interest generated by the earlj

results) elevated to the status of Major Projects in FY 1972

A MAO Steering Committee consisting of NBS scientists

advises the program manager on the content and other facets

of the program. The Committee composition is given in Table

2. In FY 72, an Evaluation Panel will serve the program and

will hold its first meeting in November.

\ w /

AJAMES R. McNESBY, Manager

Measures for Air Quality

RADFORD BYERLY, Jr

Deputy Manager
5 -

TABLE 2

F1AQ Steering Committee

Arnold Bass

Earl Beaty

John Herron

Charles Hunt

Rolf Johannesen

Phillip Klebanoff

Harold Raveche

Louis Santone

John Taylor
- 6 -

Executive Summary

It is characteristic of any research program that some projects are more successful than others and the MAQ program is no exception to this characterization. At the outset, we identified the major measurement problems as S02, particulates,

nitrogen oxides and ozone with hydrocarbons and CO of second

priority. Significant advances have been made in two general

areas, new measurement techniques and development of standard

reference materials for calibration of monitoring instruments.

Among the more definitive advances made during the first year

are

(1) The design and construction of the first apparatus

capable of measuring particle size distribution in less than

one minute.

(2) The experimental measurements (of fluorescence and

quenching, etc.) necessary for the design of the first specific,

interference-free, real-time apparatus for measuring sulfur

dioxide in the ppm region. Development is continuing on a prototype instrument to extend the measurement range to ambient

concentrations. It is noteworthy that this success was achieved

in a project classified by us as a "minor MAQ project."

(3) Standard Reference Materials were developed, partly

under EPA sponsorship, for monitoring ambient SO2 and carbon

monoxide. In progress are projects whose objectives are to

develop SRM's for oxides of nitrogen and ozone.

Some projects, seeded by the MAQ program have stimulated

interest in other agencies concerned with air pollution. For

example, the National Institute for Occupational Safety and
- 7 -

Health now supports substantial research efforts in two

.NBS Divisions partly as a result of research stimulated by MAQ

and catalyzed by the MAQ office. The Department of Transportation

has recognized the application of the MAQ project on evaluation

of physico-chemical data for air pollutants to DoT problems

in stratospheric pollution by the SST and now supports a major

effort in this area in an NBS division.

There are a number of other projects whose prognosis is not

entirely obvious at this point in time. Descriptions of these

projects as well as those to which reference has already been

made, appear in the following pages.

We have taken the position that the most effective route

to a compatible, accurate air pollution measurement system is

through an integrated program involving methods research,

SRM development, and method evaluation including collaborative

testing to establish accuracies. This position has been stated

and amplified repeatedly to other agencies of the government,

the Congress, industrial organizations and at public meetings.

We believe that the development of an accurate, compatible

measurement system is critical to our nation's effort to

implement the Clear Air Act.
OPTICAL MEASUREMENT OF PARTICLE SIZE DISTRIBUTIONS

PROJECT LEADER - D. Jennings and B. Woodward

OBJECTIVE

To demonstrate the feasibility of determining the distribution

of sizes of suspended particulates by means of laser light

scattering

APPROACH

The feasibility is to be demonstrated first by a computer

simulation of a scattering experiment, then by an actual

experiment

Figure 1 shows schematically an "ideal" experiment in which

one detects light scattered at angle 9.

In the simulation the first step (after computer programming,

etc.) Is to calculate the angular distribution of scattered

light intensity which one would expect from a particular

distribution of particles. In other words, the Mie theory

is used to calculate the angular dependence of the light

scattered from one particle. Then a weighted sum is taken

over different size particles. The result represents the

data one would obtain from an experiment in which a stream

of air laden with particles with the assumed sizes is passed

through a laser beam and the scattering is measured as a function of angle (see Fig. 2).

In step two of the simulation with this data (which has had

some information "averaged out") one uses the Mie theory to
- 9 -

calculate the particle size distribution. Thus the final

calculated distribution can be compared to the initial (input)

distribution. If the comparison is good, the experiment may

be feasible.

The experimental approach will depend on results of the

simulation

.

PROGRESS

1. The computer programs have been written, assembled,

tested and used.

2. Using several representative particle size distributions

as input, scattering "data" have been calculated. Prom the

calculated data, various size distributions have been

computed. An example is shown in Figure 3. Only spherical

particles with a single known index of refraction have been

treated. These routines are clearly able to give reasonable

solutions for moderately complicated distributions, providing

the data accuracy is great enough. If actual experimental

data yield results of this quality, such results would

represent a striking advance in the particle sizing field.

3. The real experiment has been considered and planning done.

Problems are the accuracy needed and the wide dynamic range

of scattered light intensity (-3 orders of magnitude, Fig. 2).

Basic equipment has been collected and tested. The design

of a suitable scattering volume has been considered.

4. Since it is not clear that the experiment can be done to the

required accuracy and because the ultimate results (in terms

of practical air pollution measurements) are too uncertain,

it has been concluded that the project should not be continued.
10

UJ

cc

LU

Q_X

UJ

LU

tD
11

I0C

>-

C/) z

LjJ

Q

UJCC

UJ

\-

!5O

C/)

10'

10

OOq

DOUBLE ooo

GAUSSIAN o DISTRIBUTION

o o

ooo o

00 o o

J L 20 40 60 80 100 120 140 160

SCATTERING ANGLE, 6, DEGREES

180

Fig. 2. Differential scattering—Simulated Data

For two different size distributions
12
- 13 -

DETERMINATION OF THE SIZE DISTRIBUTION OF AIRBORNE

PARTICULATE MATTER IN REAL TIME

BY A LIGHT SCATTERING METHOD

PROJECT LEADER - C. C. Gravatt

OBJECTIVE

This project will study the determination of the size

distribution and chemical composition of particulate matter

in air by a light scattering method.

APPROACH

The basic concept involves the simultaneous measurement of the

intensity of light scattered by a single particle at two

small scattering angles as it is borne by air flowing through

a scattering chamber. The ratio of the two scattered intensities

is proportional to the radius of gyration of the particle,

independent of its index of refraction. Since the particles

are measured singly and in real time, simple pulse counting

(and known flow rates) give number densities. By employing

two wavelengths of light it is also possible to determine the

index of refraction of the particle and thereby gain information

related to the chemical composition.

PROGRESS

Work performed during FY 71 has dealt with the first objective,

the determination of the radius of gyration of the particles.

An optical system was designed and built which employs a

3 mw He-Ne laser as source and an annular ring scattered light

system which monitors the scattering at 5 and 10 . The
- 14 -

Cfl

C 3 a u a!

tfl DO u

tfl TD >

ft <U

H

a

n )-i

tfl tu to u <u M 4J H C tfl O

•H o H (a a' <U ^

4J <u to

4-1 .c

to 4J to o M x 4-1 -a CJ tH c •H 3

nj

x E S O

4-1 4J

4-1 to

tfl o J3 > •H ft

aj 4J u a a) o o x;

4-1

u CD o X 4J • •H u IW 4-1 x; • <u M u x: •H a H ^H
- 15 -

use of fiber optics in the scattered light system permits

the collection of essentially all of the scattered radiation

without a complicated lens arrangement. An analog electronic

system has been developed to generate a pulse, proportional

to the ratio of the two scattered intensities, which is then

counted in a 100-channel multichannel analyzer to provide the

real time display. The electronic system is now being modified

to improve its sensitivity and response time.

In the immediate future the system will be tested and calibrated

|using polystyrene sphere samples of known diameter. Then

samples will be made up of materials of different index of

refraction to study the response of the system to index

variations

.
- 16 -

SEPARATIONS AND IDENTIFICATION OF CARCINOGENS

ADSORBED ON PARTICLES

PROJECT leader - David H. Freeman

OTHER PERSONNEL - Walter L. Zielinski, Jr., Rosalie M. Angeles,

Delmo P. Enagonio, Edwin C. Kuehner, and Herbert D. Dixon

OBJECTIVE

To develop a method for separation and analysis of certain air

pollutant carcinogens. Specific attention is focussed upon

polynuclear aromatic hydrocarbons (PAH), such as benzo [a]

pyrene (BaP), and the related family of known carcinogenic

agents. The method is intended to be simple, give meaningful

measurements, be applicable to complex mixtures, and to be adaptabli

for automatic instrumentation.

APPROACH

Liquid chromatography is the chosen area of study for the PAH

carcinogen analysis problem. The experimental methods are used non-destructively at moderate temperatures (10-80 C),

they offer high sensitivity, automatability , and high

resolution capabilities that equal or exceed those of gas

chromatography. Commercia.l apparatus can be prohibitively

costly so that simple apparatus design is of

necessary interest.

The present application of interactive gel chromatography,

developed recently at NBS , is especially suitable for PAH

chromatography and analysis. Specific interactive capabilities
- 17

lean be built Into gel network structures and large quantities

of such material can be prepared homogeneously. This is an [important base for interlaboratory standardization. The

effort to synthesize a suitable gel network is therefore

a vital part of the present investigation. The determination

of successful interactive gel synthesis lies in the

demonstration that the required separations are obtained,

'that they produce the needed isolation of specific

carcinogenic components in real samples as well as synthetic

mixtures, and that they are amenable to appropriate standards

and calibration procedures.

PROGRESS

A. Apparatus . A do-it-yourself approach to apparatus design

for liquid chromatography was developed. It provides

versatility and control that are lacking in costly commercial

LC systems. The apparatus is easily assembled, or modified.

Apparatus fabrication guidelines were developed on the basis

of reasoning by analogy to simple DC electrical resistive

circuits . Two reports on this are being prepared for

publication.

B. Theory . The basis for the theoretical development resides

In the extensive scientific literature on organic molecular

interactions that occur in liquid media. The ability of

conjugate organic solutes to undergo weak association, or interaction, to form a complex, is well known. In general,

acid-base conjugates have the ability to donate or receive a binding electron pair or active proton. Such interactions

lead to the formation of an acceptor : donor complex.
An interactive gel is prepared so that it will interact with

conjugate solute species to form a complex. The strength of a given complex is related to the solute affinity for the permanently

affixed structural groups in the gel. Differences in affinity

provide the basis for the separation of different molecular species

present in a mixture. A theoretical treatment of the solute :gel

interactive processes, including the role of competitive solvent

interactions, has been prepared for publication.

C. Stationary Phase Synthesis and Testing . Non-interactive

gels were initially studied in order to test their ability to

separate carcinogenic compounds on the basis of molecular

size. On this basis we can now specify and we have samples

of network superstructures in which relatively large PAH

molecules, such as BaP, have full permeability.

A proton acceptor gel, crosslinked polyvinylpyridine , was found to interact strongly with proton donor solutes. The

protons in an aromatic system were found to be too weakly

acidic for successful PAH separation by this gel.

The delocalized (it) electron density should be especially

significant for the achievement of chemical separation of

PAH compounds. The n electrons in BaP type molecules can form a complex with a tt electron acceptor such as silver,

or electron donor such as iodine (I

? ); this is already

known. We described the occurrence of the latter process

chromatographically , and the finding was recently published.

Silver:BaP complexation has become our present major target

for gel synthesis. Initially, we bound AgNCU onto a polyvinylpyridine gel. This gave negligible BaP interaction,

however. More recently we prepared a porous cation ex- changer in the silver ion form and the material shows good
- 19

compatibility with organic solvent systems . The material

gave a pronounced separation factor for weak tt electron

donors (benzene, anthracene) from the stronger base, BaP

.

The chromatography at this point is crude but very promising

The synthetic development and testing of refined gel network

structures is continuing.
- 20 -

PARTICULATE REFERENCE MATERIAL

PROJECT LEADER - John K. Taylor

OTHER PERSONNEL - Staff of Division 310 (ca. 15 people)

OBJECTIVE

To develop techniques and procedures for the certification

of an atmospheric particulate reference material as a means

for evaluation of chemical analysis of particulates.

APPROACH

The reliability of chemical analysis of particulate matter

is uncertain, largely because no means of evaluation are available. Analytical work must be done on expendable samples

and there is no means to intercompare either results by the same laboratory or by different laboratories. It is

the intention to obtain a large quantity of representative

atmospheric particulate matter;, and to exhaustively analyze

it, using a multi-competence approach. This material would

be made available as either an SRM or a research reference

material. Recipients would be encouraged to report the

results of their findings, which would be included in revised

reports on the material.

PROGRESS

We have been unable to obtain a large source of particulate

matter. A small sample (100 g) of material collected in

New York City was made available to us by EPA.
- 21 -

This material has been used to establish the feasibility of

the concept and to develop methodology for use when a large

sample is available. The measurements included: Morphology;

general descriptive data; elemental analysis by emission

spectroscopy, atomic absorbtion spectroscopy, polarography

,

spectrophotometry and neutron activation analysis; anion

determinations by wet chemical methods; group determinations

of organic constituents. All studies showed that it is

feasible to produce a particulate reference material. A

detailed report of the measurements is in preparation. A

design of a bag-house type collector has been developed, that

could be constructed for about $40K. It would permit

collection of about 10 lbs. of material per month.
- 22 -

IDENTIFICATION AND STRUCTURE OF CRYSTALLINE COMPONENTS

OF PARTICULATE MATTER IN AIR POLLUTION SAMPLES

PROJECT LEADER - Howard E. Swanson

OBJECTIVE

Determination of the crystalline compounds in airborne

particulate matter and the distribution of these compounds in

a city environment.

APPROACH

Using X-ray diffraction analysis we will study dustfall samples

from a large industrial city. Identification of compounds

rather than just the elements involved in this material should

be useful in establishing sources of particulate matter.

PROGRESS

Three sets of one month accumulation dustfall samples have been

obtained from eight sampling stations in Baltimore, Maryland,

for the months of December, February, and March. Most of these

samples were of sufficient quantity to fill a regular size

x-ray sample holder and give good -workable diffraction patterns.

With one exception, the bulk of these samples were quite similar

The major portions showed the same compounds found in fly ash

produced in large coal burning plants. (Fly ash from the

Black Dog Power Plant in Minneapolis, Minnesota, sent to Dr.

Byerly by Stanford Research Inst, was used in this comparison).
- 23 -

The products were mainly: SiO„ (quartz), Fe-Oj. (magnetite)

with smaller amounts of Fe

? 0^ (hematite) and CaCO_ (calcite),

plus some unburned coal and amorphous silicates.

Material from one sampling station showed approximately 75%

ctAlpO^ (corrundum) for one collection period but only small

amounts during the previous and following periods.

Other materials noted in small amounts were: C (graphite),

CaS0|.'2H„0 (gypsum), CaMg(CCU)p (dolomite), and questionable

indications of Cu

n f-Zn n uO, Zn, and a complex calcium

silicate

.

No arrangements have been made as yet to obtain samples of

airborne products from specific industries, but it is evident

from the diffraction patterns we have that such products could

be traced to some of the dustfall stations.

Two NBS spectrographic analyses for this Baltimore area served

as a check in comparing elements with the compounds found by

diffraction analysis.

A separate investigation of asbestos minerals for the

Encyclopedia of the Solid State has helped to build technical

background that could be useful in any future involvement

with asbestos as a hazardous material.
24 -

INDOOR AIR POLLUTION

PROJECT LEADER - Charles M. Hunt

ASSOCIATE INVESTIGATOR - Barry C. Cadoff

OBJECTIVE

To determine the type and composition of pollutants of indoor

air, to develop methods for measuring them under laboratory

and field conditions, to determine the source of indoor pollutants

and outdoor pollutant levels.

APPROACH

It is planned to develop a mathematical model of indoor-outdoor

pollution relationships , initiate tracer studies of air

movements in buildings, conduct a survey of indoor pollutants

and study control and abatement aspects of the indoor pollution

problem.

PROGRESS

A simple model of an air conditioned building with forced air

ventilation has been developed by which both the steady state

ratio of indoor to outdoor pollutant, as well as the rate

at which steady state is approached can be computed. More

important* the model provides a basis for analyzing the effects

of changing parameters such as the relative amounts of

recirculated air and fresh air or the efficiency of the air

cleaning system on indoor/outdoor pollutant relationships

A tracer technique using sulfur hexafluoride (SF,-) and an electron capture detector is being evaluated as a possible

tool for measuring flow rates in buildings and elsewhere. Tests
- 25 -

in a duct with known concentrations of SF^- indicate that the

electron capture detector performs as a convenient detector

in the 5-50 ppb range. Toxicological information on SF,~ is

being gathered.

Paper tape and high volume sampler measurements indicate that

indoor dust levels in the Building Research Building were

usually lower than outdoor levels. Emission spectra of the

collected dust indicated that lead was a consistent trace

element in both indoor and outdoor dust. Infrared spectra

of indoor and outdoor dust were different, probably due to more silicates in outdoor dust. Ammonium sulfate, which

probably originates in the atmosphere, has been identified

as a constituent of indoor air at Gaithersburg . This is

discussed in a short prepared discussion submitted to the

American Society of Heating, Refrigerating, and Air

Conditioning Engineers in connection with a symposium on indoor air pollution.

Simple measurements of particles generated in a room by smoking,

and operation of a vacuum cleaner or an electric fan have

been made with a light scattering particle counter. Household

aerosol sprays such as "air fresheners" and certain cleaning

aids and deodorants are being investigated as particle

generators

.

One of the needs at the present time is to develop measurement

capability for trace gases and vapors in indoor air. This,

as well as much of the material in the foregoing summary, is

discussed in NBS Report 10591 "Indoor Air Pollution Status

Report .
26

ELECTRON ENERGY LOSS SPECTROSCOPY OF POLLUTANTS

PROJECT LEADER - Chris E. Kuyatt

OTHER PERSONNEL - Stanley R. Mielczarek, Physicist

Miss Jane E. Doyle, Technician

OBJECTIVE

To develop the high resolution electron spectrometer as a gas analysis tool. This task includes the determination of

the limits of sensitivity of the electron spectrometer for

typical pollutants in air and for typical components of automobile

exhaust

The goal is to develop analysis techniques and computer programs

for the electron spectrometer which will achieve sensitivities

in the part per million range.

APPROACH

The approach is to measure electron energy loss spectra for

pure gases at knoWn pressures and under controlled conditions

of the electron spectrometer. To reduce the effect of

instrumental variations, spectra will be calibrated with a reference gas using either static or dynamic mixing or both.

Binary mixtures of known composition will then be prepared

and their energy loss spectra recorded. The spectra will be

analyzed either graphically or via digital computer and

sensitivity and accuracy determined. Multi-component mixtures

will then be investigated, for example NO in air and NO in

a mixture typical of automobile exhaust.
27

PROGRESS

The necessary pure gases and liquids have been obtained.

Gaseous samples are used as supplied from compressed gas

tanks. Liquid samples are specially prepared to free them

from dissolved gases by several cycles of freezing, pumping,

and melting.

Spectra have been obtained for Op, N„ , C0„, Ar, He, H„0,

N0„, and S0

? as well as for several molecules of special interest

to the parallel AF project: methane, benzene, acetone,

n-hexane, ethyl alcohol, trichloro-ethylene, and N„0. The

spectra are in the form of both X-Y recordings and punched

paper tape obtained via a small on-line computer.

Calculations of gas flow in the inlet system of the electron

spectrometer showed that the concentration of each component

in a gas mixture is enhanced by the square root of its

molecular weight. This result will be checked experimentally

using the gas mixing system described below.

To obtain an absolute calibration for each pure gas spectrum,

helium will be added at a known concentration by either

static or dynamic mixing. A special gas handling system for

both mixing methods has been designed, constructed, and

installed. Testing of the calibration and mixing procedures

has begun.

For all but the simplest gas mixtures, analysis of a composite

spectrum into its constituents is best done by computer fitting.

Spectra recorded on punched paper tape using a small computeroperated data system will be entered into a time-sharing

computer system via an acoustic coupler from the teletype in our laboratory. We are currently reformatting the paper tape

into a form suitable for the time-sharing computer and writing

a spectrum analysis program based on linear least squares

programs.
- .28 -

Top: Electron energy loss spectrum of

air containing a small amount of CO.

Bottom: Pure CO spectrum. Insert:

The air spectrum enlarged to show the

measured and fitted CO line.
- 29 -

MOLECULAR COMPLEXES OF GASEOUS POLLUTANTS

PROJECT LEADER - J. J. Ritter

OTHER PERSONNEL - R. C. Paule

OBJECTIVE

As originally conceived, this project sought to prepare and

characterize molecular complexes of pollutant gases suitable

for use as analytical standard reference materials. While

the original concept is still of interest, we have chosen (a)

to broaden the scope of the investigation to include a variety of approaches to the problem of NO standards, and

(b) to abandon, for the present, research on complexes of

gases other than NO.

APPROACH

(1) The suitability of mercury-encapsulated gas bubbles as certifiable standards will be experimentally investigated

for the specific case of S0

?

. (2) The concept of a permeation

device for NO based on a chemical system functioning as a NO reservoir under an equilibrium NO pressure of 1 atmosphere

or more will be investigated. (3) A third approach to NO

standards envisages the use of a selective reducing agent in

combination with a source of N0„. Given a reliable source

of N0„ which is capable of delivering that gas into a carrier gas stream at a known rate, a reducing module placed

downstream of the N0 ? source could convert the latter to a NO source. The combination could be certified as a unit, or,

if the reduction stoichiometry were sufficiently reliable,

the combination could operate in either the "NO mode" or the "NOp mode."
30

PROGRESS

1. Encapsulated Gas Bubbles--A paper describing the

techniques for preparation and use of these microstandards has

been submitted to Environmental Science and Technology. The

microbubble standards are considered to be particularly

promising for preparation of gas mixtures containing

relatively high levels of S0„ for which present permeation

tubes are not satisfactory. Preliminary experiments indicate

that the microbubble concept is also applicable to NO.

2. NO Permeation Tube —The permeation of NO through a polytetraf luoroethylene (PTPh;) tube has been examined. In separate

experiments, NO gas at about atmospheric pressure and NO over a solution of CuCl2 in ethanol were used as gas sources. It was concluded that acceptable permeation rates can be obtained under

these conditions. It is of interest that no permeation of solvent

was noted in the solution experiment, suggesting that

solution phases may be satisfactory sources of NO if other

requirements can be met.

The lack of data on the reversibility of NO uptake by metal

ions has inhibited selection of a suitable reservoir complex

from among the compounds already in the literature. A

literature report [Fraser and Dasent, JACS 82_, 3^8 (I960)]

suggested that a simple electrolytic cell using non-aqueous

solutions of CuCl„ might be applicable as a source of NO

for a permeation device. Consequently, electrolysis of the

deep purple solutions of CuClp with nitric oxide in ethanol

and acetonitrile was investigated. In contrast to the

results of the earlier workers, however, we found no production

of gas at the cathode in these systems, apparently because

degassed solutions were used in our experiments . The electrochemical approach was therefore abandoned.
- 31 -

We believe that the combination of the molecular complex

concept with the permeation tube principle offers an attractive approach to NO standards. It is apparent, however,

that exploratory synthesis work will have to be carried

out to find the suitable NO source material for use In such

a device.

3. Reducer Module NO Generator—Development of the "reducer

module" requires selection of a suitable reaction system

capable of converting N0„ to NO at a definite stoichiometry

and at low levels of incident N0„ . The module itself could

either be a catalytic convertor or contain a consumable

reagent. For practical reasons, a solid catalyst or reagent

system is preferable.

A simple reaction system has been constructed for evaluation of

candidate materials for the reducer module. A commercial

N0„ permeation tube has been used as the source of the gas.

Reactions of N0

? have been studied in three systems up to

the present:

(a) Reaction with hydrogen over platinized alumina

catalyst. This system was selected on the basis of patent

literature reporting stepwise reduction of N0 ?. The system

has been shown to be extremely sensitive to operating

parameters. Under various conditions, NO, NH~, and N„0

are obtained. The uptake of hydrogen by the catalyst system

strongly influences the course of the reaction, making

precise control difficult. This approach has consequently

been abandoned in favor of a non-catalytic system.
- 32 -

(b) Reaction of N0

? with MnO. This system is typical of

many potential candidate systems employing low-valency

transition metal compounds. It proved to be effective for

reduction of N0„ to N„0.

(c) Reaction of N0~ with Cu. Reduction of N0„ to NO was obtained. Not surprisingly, considerable loss of (NO) was observed, presumably a result of compound formation.

It has been learned from Stevens at EPA that passing N0 p over hot gold wool affects its reduction quantitatively.

A fourth, somewhat specialized concept is under consideration

in connection with MAQ interest in stratospheric monitoring

of atmospheric pollutants. As described in an informal

summary previously provided to MAQ, it appears feasible to

adapt the principle of the King Piezoelectric Sorption Hygrometer

to the detection of gases other than water by providing

selective adsorption sites on the surface of the piezoelectric

crystal. Existing coupling agent technology suggests possible

routes to surface preparation. A demonstration experiment

in our laboratory on an available model system has shown

reversible NO uptake by copper-doped aluminosilicate

structures
- 33

FRICTIONAL DEGRADATION OF RUBBER

PROJECT LEADER - James E. Fearn

ADVISORY - Joseph M . .'Antonucci

Roland E. Florin

OBJECTIVE

The objective of this work is to determine the products of

frictional degradation of rubber and from these to deduce

the mechanism and basic nature of this degradation. These

observations should illuminate the problems associated with

the permanence of rubber as a material and as a source of

pollution.

APPROACH

The present approach to the study of the degradation of rubber

involves the abrasion of rubber specimens of known composition

under clearly defined and controlled conditions. These

conditions include placing the rubber specimens under different

loads and moving them over the abrasive surfaces at various

velocities. The atmospheres under which the frictional studies

take place may be varied, .e.g., air, nitrogen, helium, vacuum

etc. Abrasive surfaces may include aluminum, or indeed any

other metallic surface, as well as asphalt, concrete, glass,

etc. Products from these experiments are collected and analyzed

PROGRESS

Pursuing the objective mentioned above and the approach,

the following apparatus (see attached photograph) was constructed. A glass cylinder with diametrically opposed

side arms was attached to an aluminum base plate through a
- 34

flange joint equipped with an ring and a screw clamp which

provided a gas-tight seal. This base plate is so equipped

that the abrasive surface may be securely attached to it.

Through the top of the glass cylinder a steel shaft carrying

the rubber sample is introduced by employing a ferro-fluid

feedthrough seal coupled with a steel bellows. This

arrangement permits translational motion of the shaft while

maintaining again a hermetic seal. The shaft is connected to

the chuck of a drill press with a capacity for maintaining

both a constant load on the rubber sample and a constant

angular velocity.

The side arms on either side of the glass cylinder permit

the withdrawing of samples in any desired fashion, the

admission of any desired atmosphere, or the attachment of any

required evacuating system.

The apparatus described above has been tested and the customary

irregularities have been corrected. Most of these

irregularities dealt with maintaining a gas-tight system

during abrading operations. Preliminary experiments included

the abrasion of an ASTM polyisoprene prototype in a helium

atmosphere under from 1 to 5 lb loads for 30 minutes or less.

The time limit was necessary because of the tendency of the

rubber sample to adhere to the abrading surface, in this

case an aluminum disc. Very little evidence of light

volatile material was indicated from a GLC examination of

this system. Placing greater weight on the rubber sample

produced shredding of the sample and some smearing in the

abrasion area. This abraded material showed solubility in

benzene in contrast to the total insolubility of the original

sample. The benzene solution of the abraded sample was filtered through a millipore filter and a sample was subjected

to GLC, yielding indication of a low concentration of a
- 35 -

substance presumed to be isoprene. It was observed that

aluminum oxide often interfered with analysis. Tackiness of some of the abraded samples suggests high temperatures during

the actual process. Efforts are underway to modify the

apparatus so that a thermocouple may be introduced to determine

the maximum temperature during the experiment

.
- 36 -

Abrasion Apparatus
- 37 -

MODULATED INFRARED LASER ABSORPTION TECHNIQUES

FOR ATMOSPHERIC POLLUTANT MEASUREMENTS

PROJECT LEADER - Melvin Linzer

OBJECTIVE

Theoretical development of frequency-modulated laser absorption

techniques for remote and point sampling of air pollutants.

APPROACH

The basic technical areas explored were frequency modulation of

infrared lasers, absolute intensity measurements, and sensitive

detection schemes. Both line-of-sight propagation for pathaverage measurements and lidar methods for pollutant profile

mapping were examined.

PROGRESS

Design criteria for a frequency-modulated laser absorption

instrument have been developed and the basis for future

experimentation is now available. The proposed device would have

the capability of detecting and quantitatively measuring

extremely small concentrations of pollutants, even in the

presence of large atmospheric and optical system losses. Both

very short and very long path measurements as well as long-range

lidar measurements would be possible.

The MAQ Office has decided not to fund this effort into an experimental stage. The theoretical analysis of the frequencymodulated laser techniques will be prepared for publication.

An experiment embodying principles not specifically developed

for this study, but nonetheless pertinent to its objective, has

been scheduled in collaboration with Bell Laboratories. A
- 38 -

Raman spin-flip laser source will be used in conjunction with

an opto-acoustic detector to measure infrared absorption in

dimethylmercury
- 39 -

ATOMIC EMISSION DETECTOR

PROJECT LEADER - Walter Braun, A. M. Bass

Technician: A. Ledford

OBJECTIVE

Develop an absolute detector for measurement of gaseous air

pollutants based upon emission from excited atoms produced in

a discharge.

APPROACH

An air sample injected into a helium stream separated into its

constituents by gas chromatography. The effluent gas stream

is subjected to a microwave discharge and the emission from

the excited atoms so formed is measured.

PROGRESS

It was found that pollutant molecules containing sulfur gave

a signal at the sulfur emission line proportional to the

concentration expressed as sulfur atoms. The detector was

,

therefore, found to be absolute. Carbon-containing molecules

were found to behave in a similar fashion. The original

plan was to assist the Analytical Chemistry Division in

assaying standard CO samples (1 to 100 ppm in air). The

samples were originally made by weight and the question of

whether these samples deteriorated with time was an important

consideration. When the original proposal was made, the

analytical chemists were not set up to perform CO assays.

However, at about the time this project was begun, the

situation had changed, and the analytical people were now
- 40 -

quantitatively converting CO into methane and analyzing their

samples via flame ionization detection. Several of their

samples were checked and very good agreement (within several

percent) was found.

A second project was undertaken: The analysis of small amounts

of NO in nitrogen (1 to 100 ppm) by measuring the atomic nitrogen

emission. Since nitrogen is present to the extent of 10°

times that of NO, we required adequate chromatographic

separation between NO and Ng • Various column packing materials

were employed without success.

We consider these efforts important for the following reasons:

(a) There is at present no absolute chromatographic

detector commercially available. For air pollution

monitoring, an absolute detector is needed.

(b) Improvements have been made in the original

design and in its overall capability. As a result of

these efforts, a better detection system will be

possible
- 41 -

THE ROLE OF THE LOWEST EXCITED METASTABLE STATE OF S0

2

IN THE PHOTOCHEMICAL PRODUCTION OF AIR POLLUTANTS

PROJECT LEADER - Richard Keller

OTHER PERSONNEL - Christer Hellner, Allan Laufer

OBJECTIVE

(a) To produce and characterize the spectral properties of

metastable species of SO p formed by the absorption of light

by S0

2

.

(b) To study the reactions of these metastable species with

common atmospheric constituents.

(c) To study the photochemical properties of these metastable

states

.

(d) To use the results of (a)-(c) to assess the role of

metastable species of SOp in air pollution.

APPROACH

(a) Use a high intensity (18 Kj ) flash photolysis apparatus to

produce large concentrations of metastable species.

(b) Use conventional flash spectrographic techniques to measure the visible and ultraviolet absorption spectra of

the metastable S0„ species. Extinction coefficients will be

determined.

(c) Study quenching by common atmospheric constituents. An

attempt will be made to determine and characterize chemical products

of these quenching reactions

.
- 42 -

(d) Use a tunable laser to produce selectively metastable

S0„ species with well-characterized energies. Repeat step

(c) with these well characterized species. Produce species with

laser and by irradiation with standard photochemical sources

in presence of common atmospheric species, study the photochemistry of the metastable species. Determine the wavelength dependence of the reactions and attempt to identify

products formed.

PROGRESS

Steps (a)-(c) under Approach have received most attention. Our

results are summarized by:

(a) The flash photolysis of S0 ? results in the temporary,

complete disappearance of the characteristic spectrum of

ground state SOp and the appearance of a new broad absorption.

This new species is formed by photons of wavelength greater

than 300 nm.

(b) The intensity of this absorption decays by a 1st order

process and the absorption of ground state SOp reappears with

the same time constant. There is no significant photochemical

decomposition of the S0

?

.

(c) The wavelength dependence and the extinction coefficients

of the metastable species have been characterized in the

region from 300 to 360 nm (see Fig. 1). The spectral range

from 360 to 800 nm was investigated and no absorptions were

observed. Work is in progress to investigate the spectral

range from 200 to 300 nm.
- 43 -

(d) The observed lifetimes of the metastable species in the

presence of SOp, COp, Ar, Xe, He, Op, and NO were determined.

The results of some of these studies are shown in Figure 2.

No photochemical decomposition of SOp was observed in any

of these experiments

.

Unfortunately, while we have much information about the

properties of the metastable species, we are unable to specify its

structure at this time. From Figure 2, it is seen that in some cases the lifetime of this species approaches one second at high pressures. Note also that in all cases the

lifetime increases as the pressure of the added gas increases.

We feel that the long lifetime and the pressure dependence

of the lifetime indicate that the metastable species is not

an excited electronic state of S0

?

. Other possibilities are isomeric species of S0 ? or complexes formed between excited S0

? molecules or between an excited SOp molecule and a ground

state molecule.

In summary, flash irradiation in the UV of S0

? results in a metastable species. This metastable species has a long

lifetime, does not react with common atmospheric species,

decays to give ground state S0

?

, and is not an excited

electronic state of S0 ?

. Work is in progress to attempt

to identify this species.
- 44 -

300

200 .

100

Absorption Spectrum of Metastable Species

Formed From Excited S02

300- 320 Wavelength (nm)

340
45

Lifetime of Excited S0 2 as a Function of Total Pressure

in Presence of Foreign Gases

o

i i i

i Pure SO z

1 1 1 A CO; (Si S0 2 ) - a Ar {Si S0 2 ) ^^ x o2 [si so2 )

800 -

.- 600 - ^^

03 J.

0)£

~

4-J1) «Ha / ° ^>

400

200 A ^^^

-

^^a

100

1 2001 1 . III.700

Total Pressure (Torr)
- 46 -

COLLECTION AND EVALUATION OF

PHYSICO-CHEMICAL DATA FOR AIR POLLUTANTS

PROJECT LEADER - D. Garvin

OTHER PERSONNEL - R. Hampson

OBJECTIVE

This project, has as its goal the publication of a series of

data sheets (or a handbook) on the physical and chemical

properties of atmospheric pollutants

APPROACH

The initial set of pollutants to be studied was 0, 0.-,, N0

p

, CO, C0

2

, S0

2

, C

2 H i+ and "PAN" (peroxyacetylnitrate ) . We have

found it desirable to expand this list to include OH, NO,

N„0, NpO,- and excited molecular oxygen, since their reactions

with the other species are often of potential importance.

PROGRESS

Preliminary Data Sheets have been prepared for 0~ and PAN.

Data sheets for and N0 ? are essei on the others is at various stagesData sheets for and N0„ are essentially complete. Work

Most of the effort has gone into an assessment of the photochemical and reaction rate data. We have tabulated the likely

reactions of the species of interest with each other and with

trace constituents of the polluted atmosphere and have collected

the relevant papers
- 47 -

During this phase it has become apparent that we must revise

our procedures in order to improve productivity. To this end,

single data sheets on a process or reaction are now being

prepared.

Physical property data has been collected for us by others.

Each of these represents a major effort. The work is merely

summarized here.

Thermochemical Properties E. Domalski, J. Minor

Transport Properties (an

extensive report, emphasizing

theory) H. Hanley

Microwave Spectrum W. Kirchhoff

High Resolution I.R. Spectra S. Abramowitz

In addition, we have collected material from NSRDS monographs

and manuscripts

.

Recent developments - During the past six months a controversy

has developed about the possible effect of high flying aircraft

on the ozone layer of the atmosphere. Study of the manuscripts

showed that this is principally a photochemical and chemical

kinetics problem. It was decided that the Physical Chemistry

Division should review the relevant data for preparation of

a set of data sheets. These are to provide basic input data for

atmospheric modelling.

Accordingly, a task force has been assembled to complete this

job during the summer of 1971 • During July approximately 10

data sheets have been prepared. Our goal is about 50.

Interestingly enough, many of the reactions are also pertinent

to tropospheric pollution. The evaluations made by this

task force will be used in the basic handbook.
48

AIR POLLUTION CHEMISTRY

PROJECT LEADER - J. T. Herron

OTHER PERSONNEL - R. E. Huie

OBJECTIVE

The objective of this project is the kinetic characterization

of the elementary reactions which may play an important role

in air pollution chemistry. Specifically, this includes the

reactions of atomic oxygen, singlet molecular oxygen, ozone

and hydroxyl radicals with primary organic pollutants, and

with the oxides of nitrogen and sulfur.

APPROACH

The approach used is a combination of laboratory studies with

data compilation and evaluation.

The laboratory programs center around the NBS chemical kinetics

mass spectrometer, used for the study of atomic oxygen and

singlet molecular oxygen chemistry, and the resonance fluorescence

apparati at NBS and at the University of Maryland used for

the study of atomic oxygen reactions.

In the case of the atomic oxygen reactions, the laboratory

program is designed to complement the data evaluation program

by establishing absolute rate constants for key reactions to

be used in converting the existing large body of relative rate

measurements into absolute rate constants, and to provide

data on important reactions where none exists or where the

existing data is unreliable.
- 49 -

PROGRESS

The principal accomplishments in FY 1971 have been in the

measurement and evaluation of atomic oxygen rate constants,

and in the study of the reactions of singlet molecular oxygen.

Rate constants have been measured over a wide range of total

pressure and temperature for the reaction of atomic oxygen with

ethylene. This is the key reaction in the evaluation of the

kinetic data on the reactions of atomic oxygen with organic

compounds

.

Rate measurements have also been completed for the reactions

of atomic oxygen with the cycloalkanes , and 1-butene . Nearing

completion is work on the haloalkenes , the higher olefins,

Op and NOp. The latter two being of particular interest in

stratospheric chemistry, are being studied at temperatures down

to 220 K.

The data compilation and evaluation on atomic oxygen—organic

compounds is underway and should be complete by about

September (to appear in Progress in Reaction Kinetics and

as part of the NSRDS series).

A compilation of rate constants at 300 K covering 104 reactions

has been prepared for use in the NBS Air Pollution Handbook.

An important objective of the work on singlet molecular

oxygen was the evaluation of chemical titration methods for the

measurement of singlet molecular oxygen concentrations. We

have compared 2,5 dimethylfuran, tetramethylethylene, and

N,N-dimethylisobutenylamine as titrants and found that only

2,5-dimethylfuran was suitable. To confirm the validity of
- 50 -

the titration, we have used an argon resonance lamp in

conjunction with a pair of parallel plate electrodes to

compare the relative photoionization cross sections of

C

2 H2

, C

2 H l4 , NO, and

2

( Ag) (as measured by titration). The

values found by us are in excellent agreement with those found

by other workers, and lend strong support to the titration

technique

In addition to evaluating titration methods, we have measured

rate constants for 2( Ag) reactions over a range of pressure

(0.5 to 8 torr). We find no evidence for a pressure effect

and conclude that .the large body of relative rate data

obtained from solution studies as well as from low pressure

gas phase work is transferable to real atmospheric situations.

From this in turn we conclude that singlet molecular oxygen

plays an insignificant role in the oxidation of organic

molecules in the atmosphere.
- 51 -

NBS AIR SAMPLING STATION

PROJECT LEADER - John K. Taylor

OTHER PERSONNEL - Rolf A. Paulson

OBJECTIVE

To establish an air monitoring station on the NBS site.

This station will then be used not only to provide local air

quality data, but will give firsthand information on the

problems involved in such measurements.

APPROACH AND PROGRESS

The location for the station was selected after numerous discussions with NBS officials. A concrete platform 10' x 20' was constructed with four power outlets. An aluminum shelter

building 7' x 10' was erected. Monitoring equipment was purchased. The station is now in operation for measurement

of total particulates, dustfall, and sulfation. Other

measurements will be made as equipment becomes available.

The station will permit familiarization of NBS staff with availabli

instrumentation under field conditions and it is the intention

to do this

.
- 52 -

NBS Air Monitoring Station
- 53 -

FAR IR CARBON MONOXIDE MONITOR

PROJECT LEADER - H. A. Gebbie

OBJECTIVE

Design and construct an apparatus to measure CO concentrations

to be expected in automobile exhausts.

APPROACH

Measurement of far IR absorption in the pure rotational

spectrum of CO using the properties of a two-beam Interferogram

will be attempted. Multiple path traversal through the sample

will be achieved by means of a non-resonant spherical cavity.

PROGRESS

A device has been constructed as shown in Figure 1, which

includes a stepped mirror interferometer to increase

selectivity. The steps are designed to match specific

parameters of the CO molecule. Distinguishing features of

the design are:

1. Use of the non-resonant spherical cavity to

enhance the absorption.

2. The stepped mirror is fixed in position and is

not scanned.

3. The output of the (thermal) detector measures

directly the amount of CO in the sample cell.

4. The only moving part is the vibrating mirror of the

phase modulator.
- 54 -

The only serious interference is H

? which is readily removed

from the sample by conventional techniques. Carbon dioxide

does not interfere since it has no far IR absorption.

A number of typical vehicle exhausts has been analyzed including

idling modes. The limit of detection in the present

prototype appears to be approximately 0.3 percent CO.
55

GAS ANALYSER USING A NON-RESONANT CAVITY ABSORPTION

CELL AND A SELECTIVE INTERFEROMETER

PHASE

MODULATOR

| >;:/•»' ///> jj\ MIRROR

INTERFEROMETER*

RADIATION

SOURCE

ENTRANCE APERTURE

FIXED STEPPED MIRROR

NON-RESONANT

CAVITY

CONTAINING

GAS SAMPLE

DETECTOR

PRINCIPAL FUNCTIONS

1. A long absorption path is achieved by the radiation making many passes

through the gas because the metal cavity wall has high specular

reflectivity.

2. The steps on the mirror are designed to match specific molecular

parameters of the gas being analysed.

3. The output of the detector is then a direct measure of the amount

of gas in the cavity.

FIGURE 1.
- 56

CHEMICAL COMPOSITION OF POLLUTED AIR

PROJECT LEADER - Harold W. Woolley

OBJECTIVE

The project objective is to estimate magnitudes of effects

on equilibrium constants and equilibrium compositions of

N„ + 0„ mixtures due to interactions between molecules with

particular regard to reactions occurring in automobile

power plants. The influence of reaction rates is also considered

APPROACH

A computer program written earlier for high temperature

reactions was adapted to the examination of equilibrium properties

of N„ and

? perturbed by the presence of COp. Values of

thermodynamic functions from JANAF tables are read in for

each constituent for 20 temperatures ranging from 100 K to

6000 K.

Estimates for effects of interactions on the equilibrium

constants and the equilibrium compositions were based on sets

of pair second virials , B, and third virial values, C, and

their derivatives for major constituents as read in as a short

table for several temperatures. This is based on an equation

of state in the form

PV/RT = exp(s

1 /V + s2 /V 2

) 2 where s-, = B and s ? = C - B /2.
- 57 -

PROGRESS

Various modifications of calculation procedures for the approach

to chemical equilibrium were examined, depending in part on the particular path for the chemical reactions presumed to be of

greatest influence in the process. Calculations have been

made for effects on nitric oxide concentrations at equilibrium

as a result of varying such conditions as temperature and

density and the concentration of carbon dioxide. Several

cases such as for the following sets of reactions have been

considered

:

2 = 2

N

2 = 2 N

+ N = NO

2 = 2

N + = N + NO

2 + NO = + N0

2 N + N0

2 = 2 NO

2 = 2

N

2 + = N2 + N

2 = 2 NO

co

2 = CO +

N

2 + = N

2 + N

2 = 2 NO
- 58 -

It was found that the introduction of CO- into the system

has no great effect on the equilibrium concentration of NO

at any conditions of temperature and pressure specified.
- 59 - FIELD EMISSION SPECTROSOPY

PROJECT LEADER - Ralph Klein

OBJECTIVE

To study the behavior of NO adsorbed on ruthenium and to use

this study to assess the feasibility of using ruthenium as a catalyst for the conversion of NO to the elements.

APPROACH

The method used is that of field emission microscopy in which

a field emission tip of ruthenium is centered in a molecular

beam of NO. The ruthenium tip temperature is maintained at

4.2 K during the condensation. Temperature control is such

that the ruthenium surface may be heated in an approximately

square wave mode to any desired temperature up to the melting

point of ruthenium (2700°K).

PROGRESS

The first observation was that it was impossible to achieve

complete coverage of NO on the tip. In the normal procedure the

axis of the emitter is perpendicular to the axis of the

molecular beam. The emitter tip, "sees" the beam only on its

upper half surface. The initial condensation is by way of

chemisorption. Completion of the monolayer is followed by

physical adsorption. Heating of the tip to a relatively

low temperature (50-60°K) results (with gases observed) in the

migration of the physi-sorbed layer to the under side of the

tip where it is immediately trapped and chemisorbed. In this

way j a tip covered with a monolayer of the gas is prepared.
- 60 -

However, NO proved to be unusual in that, even after long

deposition, no migration of the NO to the unexposed portion

was observed after heating. Several explanations may be

advanced. One, that NO does not condense on a monolayer

surface, is very unlikely. Two, the NO is bound so weakly

in the second layer that it desorbs before migration. Three,

the NO is so strongly bound, even as a physisorbed layer,

that much higher temperatures are required for migration of

the physisorbed layer, so high that it desorbs before it

migrates. Four, disappearance of NO is by way of diffusion

into the lattice, also very unlikely. Explanation two is

currently favored.

Heating of the tip half covered with NO to still higher

temperatures (about 300 K) causes decomposition. The oxygen

pattern can then be observed. It is quite clear that NO

decomposes very easily on a ruthenium surface. Further

studies on this system are in progress.
- 61 -

IDENTIFICATION OF FREE RADICALS IN SMOG MECHANISMS

PROJECT LEADER- Dolphus E. Jlilligan

OTHER PERSONNEL - Marilyn Jacox

OBJECTIVE

Such species as CH_0 and HO

? are believed to be important in

smog forming mechanisms. Characterization of their spectra

in the ultraviolet would enable studies to be made of the

kinetics of these species. The objective of this work is to

find the ultraviolet spectra of such species.

APPROACH

An attempt will be made to form CH_0 by the vacuum-ultraviolet

photolysis of methanol and of its deuterium-substituted

counterparts isolated in solid argon and in solid nitrogen

at 14 K. The vacuum-ultraviolet photolysis of Ar : OpiHCl and

Ar:Op:H„0 will be done to produce H0

? in a matrix.

PROGRESS

Photolysis sources used for these experiments have included

the 1470-A xenon resonance line, the 1067-A argon resonance

line, and the 1216-A hydrogen line. The highest relative yield

of the CH_0 product is obtained using 1470-A radiation.

Since there is a well-defined absorption due to this species

in the spectral region characteristic of 0-H stretching

absorptions, it is believed that the structural formula is

HpC-OH. Upon exposure of the sample to mercury-arc radiation

of wavelength shorter than 2800-A, photodecomposition of this

species occurs, indicating the presence of a continuum

absorption in the 2500-2800-A spectral region.
- 62 -

Photolysis of Ar„: Op:HCl and Ar:Op:HpO samples of mole ratio

200:1:1 have led to the stabilization of considerably higher

concentrations of H0

? than have previously been observed in

matrix-isolation experiments. CU and H„0

? are also produced

in significant concentration, and, in the HC1 experiments,

Cl-0-0 and H0C1. Despite these higher concentrations of H0„,

studies of the 1800-9800-A spectral region have not yielded

any absorptions which may be assigned to this species, nor

does any decrease in the H0„ absorption result even on prolonged

irradiation of the sample by the full light of a mediumpressure mercury arc. A detailed normal coordinate analysis

of the vibrational spectrum of H0„ has been performed on the

Univac 1108 computer, and agreement with all of the observed

isotopic frequencies is excellent, assuming a valence angle

of 105° + 5°.

A manuscript has been prepared and submitted for publication

in which detailed infrared spectroscopic studies of the

interaction between low-energy electrons and alkali metal

atoms and various nitrogen oxides are reported. Most

significant to air-pollution studies is the discovery that 0~

produced by the interaction of electrons with N„0 persists

for a sufficient time in an argon matrix to permit diffusion

from the site of its production and reaction with NpO or with

NO to produce detectable concentrations of N„0~ and of NO-,

respectively
- 63 -

CALIBRATION STANDARDS VIA PYROLYSIS

PROJECT LEADER - Wing Tsang

OBJECTIVE

The generation of known concentrations of important pollutants

in air.

APPROACH

Specified air pollutants of known concentrations will be

synthesized through the pyrolysis of larger and more stable

molecules. The pollutant molecule is one of the fragments

into which the pollutant decomposes and the other is an easily measured hydrocarbon.

PROGRESS

Demonstrated in a qualitative fashion that this approach will

(work for -formaldehyde, acetaldehyde , sulfur dioxide (butadiene

sulfone) and butadiene (cyclohexene) . Tests have been limited

by the insensitivity of detection devices. New equipment has

been ordered. Some calculations have been made with regard

to the design parameters for a 1 ppm formaldehyde generator

at a flow rate of 50 cc/min and lifetime of 6 months.
- 64 -

FLUORESCENCE DETECTOR FOR S0

2

PROJECT LEADER - H. Okabe

OBJECTIVE

Study the fluorescence stimulated by radiation in the 200- 230 nm wavelength region of spectrum to determine the feasibility of

this method for measurement of ambient S0p

.

APPROACH

The feasibility of the fluorescence measurement method requires

a knowledge of the absorption coefficient, fluorescence

intensity, radiative lifetime and quenching efficiencies by

0„ and N„ . These factors will be studied.

PROGRESS

A lifetime of the excited S0 p obtained from absorption coefficient

-9

measurements was found to be 9 x 10 sec. Fluorescence

intensity was measured as a function of wavelength and pressure

of air in order to determine quenching efficiencies . It was found that in ambient air fluorescence is still measureable

and that S0

p may be measured at ambient concentrations.

The result suggests it would be worthwhile to construct a prototype device for measurement of ambient S0„ and this work

is underway.
- 65 -

NITRIC OXIDE SRM DEVELOPMENT

PROJECT LEADER - Ernest E. Hughes

OTHER PERSONNEL - William D. Kinard : Rolf A. Paulson

OBJECTIVE

Determine the stability of NO in nitrogen and nronane in air

for their eventual use as Standard Reference Materials for source

testing.

APPROACH

Chemiluminescent reactions provide sensitive and selective

methods for nitric oxide analysis. The referee methods for

automotive nitric oxide and ambient photochemical oxidant

include such techniques. Chemiluminescence apparatus will be

constructed and its analytical reliability evaluated for

NO measurement . Procedures will be developed for certification

analysis of SRMs , including especially the assessment of

stabilities of NO-N p mixtures' in cylinders.

PROGRESS

Components were obtained from which a chemiluminescent

system was assembled. The operation of the system has been

checked out, using the ozone-ethylene reaction. A

procedure is under development for the intercomparison of ozone generators, using the chemiluminescent method. Apparatus

for utilization of the ozone-nitric oxide reaction for

determination of the latter is being completed, and will be

evaluated in the near future. Studies of the stability of N0-

nitrogen mixtures in steel cylinders are in progress.
- 66 -

Apparatus for Analysis of Air Pollutants

by Chemiluminescent Techniques
- 67 -

INSTRUMENTATION ASSISTANCE TO THE NATIONAL AIR

POLLUTION CONTROL ADMINISTRATION

PROJECT LEADER - G. A. Dines

OTHER PERSONNEL - R. M . McCabe

M. L. Greenough

OBJECTIVE

Process data taken on magnetic tape at the 6 Continuous Air

Monitoring Project (CAMP) stations of EPA. Summaries output

on paper, detailed output on microfilm.

APPROACH

Develop software to process the data tapes. This involves

analysis of the many tape and operator errors at the

monitoring stations, and the development of operator

procedures and software to either prevent or recover from

the errors

.

PROGRESS

The software is virtually complete. About 40 reels of data

tape have been run so far and the remaining 40 in the backlog

will be processed within the next two weeks . At that point,

product will be on a current basis.
68

THE SULFUR DIOXIDE PERMEATION TUBE

PROJECT LEADER - John Taylor and E. Hughes

OBJECTIVE

To demonstrate the certifiability of sulfur dioxide permeation

tubes as SRMs

APPROACH

Study the behavior of the permeation tubes over long periods

of time under conditions which might be encountered during

calibration and use. The tube is made of teflon, in which is

contained liquid sulfur dioxide, and has the physical dimensions:

roughly of a pencil. The effect of accumulations of grease on the tube's exterior, exposure to water, effect of purity of SOp, were to be investigated along with flow rate and temperature

dependence

PROGRESS

The effect on permeation rate of wall thickness and uniformity

was determined. The time taken to reach a constant permeation

rate after removal from storage at -20 to -30°C was measured

and found to vary from 24-48 hours. Equilibration is achieved

reliably only when at least 24 hours is allowed following a temperature change. The effects of these parameters mentioned

in the "approach" paragraph were evaluated experimentally.

The tubes are useful subject to stringent temperature and

flow rate control. Most of the above work was done before the

establishment of MAQ and was funded entirely by EPA. On

December 1, 1970, Serial No. 1, SOp permeation tube was presented by Dr. Branscomb to the Administrator, National Air

Pollution Control Administration, Dr. John Middleton (see

frontispiece). For details, see NBS Tech. Note 545.
- 69 -

CD£ONO

bOCH

Ph3

K>cd

CDS

X3 . Sh T3

ctiO

C £!

•H -P W CDB s

Ctf

H

•H « H

rH T3 •H 0) 13 ?H

QJ

-cs Oh a (in cd 3

.a

FhO

H

rH cti >» J^ «j -p

En 3

<D

C

C £o QJ

1-3 £

-P

fn >> Q ,Q
70 -

THE NITROGEN DIOXIDE PERMEATION TUBE

PROJECT LEADER - John Taylor and E. Hughes

OBJECTIVE

To examine the suitability of NO„ permeation tubes as SRMs

APPROACH

It is essential for a field calibration permeation tube that

its permeation rate be independent of time. Preliminary

experiments with NO2 permeation tubes showed this not to be

the case, the rates decreasing monotonically over the life

of the tubes. The research program aimed to discover the reason for this behavior and to introduce appropriate measures

to ensure a constant rate. Effects of humidity and temperature

were to be studied systematically.

PROGRESS

Twenty permeation tubes purchased commercially all showed

rates of weight loss decreasing with time over the life of the

tube. Further, the rates are inconveniently high for ambient

air applications. Reduced rates were obtained by altering

the physical dimensions and finally by means of a new design,

the microbottle. This consists of an impermeable glass tube

capped with a teflon disc through which the NO- permeates. It was found that moist air depresses the rate and produces a blistering of the tube. Water, in the form of fuming nitric acid, was found in the tubes that had been exhausted. The

introduction of P-,0,- into the microbottle reduces the rate of

c. the drop in permeation rate by an order of magnitude. Research

is continuing on this system. This project is funded entirely

by the EPA.
- 71

OZONE

PROJECT LEADER - John Taylor, T. Mears

OBJECTIVE

To define conditions under which an ultraviolet light source may

be incorporated into a device usable as an SRM for ozone measurement and to fabricate prototype devices.

j APPROACH

An ultraviolet light source with output at 184.9 nm is combined

with a quartz tube through which air flows at a measured rate.

By exposing controllable fractions of the air to the light

,

varying concentrations of ozone are produced in the air stream.

The absolute standard for measurement of the amount of ozone produced

is the neutral buffered KI method.

PROGRESS

A number of devices have been fabricated and research is in

progresss to relate such parameters as flow rate and time to

measured ozone generation rates. This project is funded entirely

by EPA.
- 72 -

EMISSIONS OF RUBBER FROM AUTO TIRES

PROJECT LEADER - R. L. Raybold

OBJECTIVE

To determine the fate of material worn from automobile tires

APPROACH

Since we desire to measure the products of normal wear of

tires and since obtaining "normal wear" and capturing the

products tend to be mutually exclusive goals, some compromises

had to be made. It was decided to run full scale tires, at

reasonable speeds and loads inside a closed room so that the

products are trapped. Provision is made to measure suspended

particulates and volatiles, and to collect particles that

fall out.

PROGRESS

Facilities for running tires at up to 35 miles per hour and

loads of 1000 pounds around a 14-foot diameter paved track

are available at Amoco Research, Whiting, Indiana. A

contract was negotiated and let to run the tests. The

contractor has begun creoarine for the tests which will be run several days in early FY 72. Preliminary analysis of samples

of particulate matter collected at the NBS tire testing

facility have showed no polynuclear aromatic hydrocarbons.

They have also indicated that the material worn from tires

in the NBS tests (which are not wear tests) appears to be

a degraded material, i.e., not bits of "virgin" rubber.

Preparations for the particulate collection during the Amoco

tests have been made.
73 -

APPENDIX

LIST OF PUBLICATIONS, FY 1971

Herron, J. T. and Huie, R. E. , "Mass Spectrometric Studies of

the Reactions of Singlet Oxygen in the Gas Phase," Annals of

the New York Academy of Sciences 171 , 229 (1970).

Braun, W., Peterson, N. C., Bass, A. M., and Kurylo, M. J. "A Vacuum Ultraviolet Atomic Emission Detector. Quantitative

and Qualitative Chromatographic Analysis of Typical C, N,

and S Containing Compounds," Journal of Chromatography 55 , 237 (1971).

Milligan, D. E. and Jacox, M. E. "Ma t r ix- Iso la t ion Study of the

Interaction of Electrons and Alkali Metal Atoms with Various

Nitrogen Oxides. Infrared Spectra of the Species NO -

, NO", and

N

2 0:;." J. Chem. Phys., October 1971.

Okabe , H., "Fluorescence and Pre dis s ocia t i on of S0„." To be

published in J. American Chem. Soc. , Communications to the

Editor . Paule , R. C., "A Low Level Gas Pollution Standard," to be

published in Environmental Science & Technology.

McNesby, J. R. "Pollution Measurements Lack Standards," Chemical

and Engineering News, May 10, 1971.

McNesby, J. R. and L i ch t en s t e in , S., "Measures for Air Quality

Program at NBS: Getting Solid Readings on Air Pollution," to be

'published in Pollution Abstracts.

Freeman, D. H., Annual Progress Report (NBS Technical Note 589)

describing the NBS developed liquid chromatographic apparatus.

Freeman, D. H., "Interactive Gel Networks. I. Treatment of

Simple Complexation and Masking Phenomena," Analytical Chemistry,

December 1971 issue.

'Freeman, D. H. and Enagonio, D. P., "Interactive Gel Networks

for Organic Separations," Nature, Physical Science, 230 , 135 (1971)

8 issues of the MAQROSCOPE, The Measures for Air Quality Newsletter.

IFORM NBS-114A (1-71)

2. Gov't Accession No.

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS TN-7113. Recipient's Accession No.

4. TITLE AND SUBTITLE MEASURES FOR AIR QUALITY

Annual Report--FY 1971

5. Publication Date January 1972

6, Performing Organization Code

7. AUTHOR(S) J. R. McNesby and R. Byerly

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. Project/Task/Work Unit No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

11. Contract/Grant No.

12. Sponsoring Organization Name and Address Same as No . 913. Type of Report & Period Covered Interim

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summaty of most significant information. If document includes a significant bibliography or literature survey, mention it here.)

A compilation of reports covering the air pollution related

projects at NBS during FY 1971. There are 23 projects

in all, and they cover many areas of air pollution measurement. A table of contents lists descriptive project titles.

17. KEY WORDS (Alphabetical order, separated by semicolons) Air pollution; carbon monoxide; hydrocarbons; nitrogen oxide; ozone;

particulates; standard reference materials; sulfur dioxide.

18. AVAILABILITY STATEMENT

|~^1 UNLIMITED.

I I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

77

22. Price

TO cents

USCOMM-DC 66244* P71

* U. S. GOVERNMENT PRINTING OFFICE : 1972 481-329/156

NBS TECHNICAL PUBLICATIONS

PERIODICALS JOURNAL OF RESEARCH reports National

3ureau of Standards research and development in

jhysics, mathematics, chemistry, and engineering,

iomprehensive scientific papers give complete details

)f the work, including laboratory data, experimental

procedures, and theoretical and mathematical analyses. Illustrated with photographs, drawings, and

charts.

Published in three sections, available separately:

• Physics and Chemistry

Papers of interest primarily to scientists working in

these fields. This section covers a broad range of

physical and chemical research, with major emphasis

standards of physical measurement, fundamental

constants, and properties of matter. Issued six times

year. Annual subscription: Domestic, $9.50; $2.25

additional for foreign mailing.

i Mathematical Sciences

Studies and compilations designed mainly for the athematician and theoretical physicist. Topics in (mathematical statistics, theory of experiment design, numerical analysis, theoretical physics and chemisty, logical design and programming of computers

and computer systems. Short numerical tables. Issued

quarterly. Annual subscription: Domestic, $5.00;

$1 .25 additional for foreign mailing.

• Engineering and Instrumentation

Reporting results of interest chiefly to the engineer

and the applied scientist. This section includes many

of the new developments in instrumentation resulting from the Bureau's work in physical measurement,

data processing, and development of test methods.

It will also cover some of the work in acoustics, applied mechanics, building research, and cryogenic

engineering. Issued quarterly. Annual subscription

Domestic, $5.00; $1.25 additional for foreign mailing.

TECHNICAL NEWS BULLETIN

The best single source of information concerning the

Bureau's research, developmental, cooperative, and

publication activities, this monthly publication is designed for the industry-oriented individual whose

daily work involves intimate contact with science and

technology

for engineers, chemists, physicists, re- search managers, product-development managers, and

company executives. Annual subscription: Domestic,

$3.00; $1.00 additional for foreign mailing.

N0NPERI0DICALS

Applied Mathematics Series. Mathematical tables, manuals, and studies.

Building Science Series. Research results, test methods, and performance criteria of building materials, components, systems, and structures.

Handbooks. Recommended codes of engineering and industrial practice (including safety codes) de- veloped in cooperation with interested industries, professional organizations, and regulatory bodies.

Special Publications. Proceedings of NBS conferences, bibliographies, annual reports, wall charts, pamphlets, etc.

Monographs. Major contributions to the technical

literature on various subjects related to the Bureau's

scientific and technical activities.

National Standard Reference Data Series. NSRDS provides quantitative data on the physical

and chemical properties of materials, compiled from

the world's literature and critically evaluated.

Product Standards. Provide requirements for sizes, types, quality, and methods for testing various industrial products. These standards are developed co- operatively with interested Government and industry groups and provide the basis for common understanding of product characteristics for both buyers and

sellers. Their use is voluntary.

Technical Notes. This series consists of communications and reports (covering both other agency and

NBS-sponsored work) of limited or transitory interest.

Federal Information Processing Standards

Publications. This series is the official publication within the Federal Government for information on

standards adopted and promulgated under the Public Law 89—306, and Bureau of the Budget Circular A—86

entitled, Standardization of Data Elements and Codes

in Data Systems.

Consumer Information Series. Practical information, based on NBS research and experience, covering

areas of interest to the consumer. Easily understandable language and illustrations provide useful back- ground knowledge for shopping in today's technological marketplace.

NBS Special Publication 305, Supplement 1, Publications of the NBS, 1968-1969. When ordering, include Catalog No. C13.10:305. Price $4.50;

$1.25 additional for foreign mailing.

Order NBS publications from: Superintendent of Documents Government Printing Office Washington, D.C. 20402
I.S. DEPARTMENT OF COMMERCE

national Bureau of Standards

Washington. D.C. 20234

IFFICIAL BUSINESS

enalty for Private Use. $300

POSTAGE AND FEES PAID

U.S. DEPARTMENT OF COMMERCE