Air Pollution Bernard E. Saltzman* and William R. Burg Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio 45267
This review covers the literature from late 1974 to late 1976 and is a continuation of previous reviews (21A). A primary source was Air Pollution Abstracts ( I A )published by the U.S. Environmental Protection Agency's Air Pollution Technical Information Center (APTIC). This scanned approximately 7000 serial publications and included over 26 000 abstracts during the two years preceding its discontinuance in June 1976; over 2000 citations appeared in the subject field 3: Measurement Methods. Because of space limitations, a complete listing was not possible; only about 650 articles were listed in this review. Selections favored the more relevant and innovative research published in journals. Many contract reports and articles in foreign language publications not readily available were not included. To assist the reader with articles not in English, the language is listed, and the Air Pollution Abstract (APA) number of an English abstract is given in the citation. Note that this number not the APTIC accession number, but that of its consecutive listing in the publication.
REVIEWS, BOOKS, AND CONFERENCES Measurement and monitoring techniques have assumed enough importance to require numerous sessions for coverage at annual meetings of societies such as the American Chemical Society, the Air Pollution Control Association, and the American Industrial Hygi'ene Association. Extensive categorized abstracts (IA, 20A) are available, as well as listings of forthcoming scientific meetings (14A).Books were published dealing with calibration techniques ( 2 A ) ,monitoring instruments ( 3 A ) ,aerosols ( 7 A ) ,and odors (6A, 24A). Widely used methods were described in manuals (22A,25A). The previous review listed 500 references (21A)for literature from 1972 to 1974. Modern methods ( 17 A ) commercially available (15A) and new ( 4 A ) instrumentation and the impacts of new developments in spectroscopy, satellite transmission of environmental data, remote sensing, and computerized data processing for environmental measurement (13A) were described. A bibliography of 1460 references listed laser applications to atmospheric sciences (1OA).Other specific reviews covered visible, UV, and x-ray fluorescence spectroscopy (5A, 16A),the use of chemical derivatives in gas chromatography ( 8 A ) ,applications of tunable lasers (23A),and aerosol measurements (1IA, 19A). Methods for sampling, analyzing and testing of solid and gaseous fuels (12A)and soil samples (for analysis of environmental contaminants) (9A) were described. A bibliography of 1055 references dealt with the occurrence and analysis of polycyclic aromatic hydrocarbons (18A) SAMPLING AND DATA COLLECTION D a t a Handling. Considerable literature was concerned with monitoring systems and networks and data processing. Details of monitoring systems and means for transmitting, checking and processing data were given (3B, 13B). The types and purposes of air monitoring networks, their necessary densities, and uses of pollutant monitoring and meteorological instruments were outlined (14B).A numerical model of pollutant transport providing generality and flexibility for handling complex and time-varying emissions and atmospheric conditions was developed and applied to sulfur dioxide in Melbourne (10B).A portable microprocessor for treating raw air quality monitoring data could be programmed a t the deployment site and produced a hard copy or tape record of results (15B).Statistical procedures comparing measurement data with air quality standards served as the basis for tactical decisions ( 11B). Deviations of data obtained automatically by telemetry from data read manually from charts for sulfur oxides, dusts, nitric oxide, nitrogen dioxide, oxidants, and carbon monoxide were small, and only 10% of the data required adjustments (9B). Special procedures reported in-
cluded data processing techniques for aircraft sampling of point and source plumes ( I B ) ,an acid pollution monitoring and alarm system in Paris (17B),statistical treatment of atmospheric aerosol data (18B),and a system for recording concentrations in different colors characterizing the wind directions ( 4 B ) . Examples illustrated pairwise correlation statistics, cluster analyses algorithms, enrichment factors, and pollutant concentration roses for multiple element analyses of atmospheric particulate samples (16B).Retention times and upper frequency responses of photometric sensors and associated electronics were optimized (8B).Monitoring instruments, automatic calibration and telemetry systems, and maintenance problems were described (2B).Evoked response signal averaging improved signal to noise ratios (7B). Computerized statistical packages and programs, algorithms, techniques, and hardware for the environmental scientist were reviewed (12B).A statistical model described the time behavior of pollutants (6B).Analyses of 11metals from quartered sampling filters showed residual standard deviations of 10%and brought into question the reliability of using ambient air as a common standard for intercomparisons of air sampling instruments (5B). Sampling Methodology.General sampling methods rather than procedures for specific substances are presented in this section. Loud noise from some high volume samplers was attenuated with 2-inch thick foam rubber lining on the insides and bottoms of the samplers (19C). High volume samplers were found to contaminate the air sample with copper emitted from the motor (13C) and with a small amount of carbon aerosol from the abrasive wear of the motor brushes (5C). Unwanted aerosol particles were also generated in the bearing system of an aerosol spectrometer (15C). Different designs of inlets for high volume samplers yielded different results for larger particles and high wind velocities, for which isokinetic sampling was recommended (22C). Filter materials and the factors affecting the collection of particulates were reviewed (23C).The weight of water irreversibly absorbed during sampling air a t 90% humidity for 24 hours through an 11-cm Whatman 41 filter weighing 0.8 g was 4.2 mg (BC). Paired high volume sampling of suspended particulates with Whatman 41 filters and glass fiber filters indicated that the former could be used, but that they gave slightly lower results and required extra procedures to avoid errors from their moisture contents (14C).The efficiencies of quartz fiber filters were evaluated over a range of temperatures, particle sizes, volatilities, and gas velocities (12C). When carefully dried and handled, Anderson impactor glass fiber substrates lost weight of no more than 0.20 mg/stage during sampling (21C). Sampling efficiency of Fluoropore filters for sulfuric acid aerosol was only 1%( I 7C) and of a high volume sampler for arsenic trioxide only 10% (IOC).Analysis of submicrogram samples of aerosols was achieved by impaction sampling on a field emitter which was subsequently transferred into a mass spectrometer (20C). The sorption of ammonia and nitrogen oxides by materials used in constructing sampling lines such as stainless steel, glass, and rubber were evaluated (3C).Sampling tubes filled with gas chromatographic packings were used for efficient collection of organic pollutants and their later release by heat into a gas chromatograph (18C). Concentrations of volatile hydrocarbons below 1 ppm were collected on a Porapak Q column and concentrated for gas chromatographic analysis by heat desorption and condensation in a liquid nitrogen cold trap (4C).Sub-ppb concentrations of ethylene were quantitatively collected on Porapak S (7C) and of pesticides on Chromosorb 102 (24C).Retention volumes of organic compounds on silica gel were determined as functions of humidity, concentration, layer thickness, desorption temperature, and the number of desorptions per tube (6C). Ultra trace-analysis of air was achieved by condensing pollutants in a liquid niANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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trogen trap and later releasing them into a gas chromatographic-mass spectrographic system (2C).The design, construction, and performance of a balloon-borne low temperature air sampler were described (11C). Dosimeters for gaseous pollutants utilizing chemically impregnated filter papers in plastic tubes were affected by wind velocity and direction; wrapping with a nylon net was proposed to minimize errors ( I C ) . Filter paper impregnated with NaOH efficiently collected organic acids, and with oxalic acid collected methylamines and ammonia. The samples were extracted and analyzed by gas chromatography (16C).Airborne bacteria were more viable when collected on gelatine filters than on membrane filters (9C). PARTICULATES AND AEROSOLS
Collection and Sizing. A significant amount of work was conducted to measure and characterize aerosols in ambient air. The limitations of fibrous dust concentration measurements and results for two Ruhr cities were presented (130). Cleaner samples on a 0.2-pm pore diameter Nuclepore filter for examination for asbestos by electron microscopy were obtained by using an unsupported 5-pm pore diameter Nuclepore pre-filter to remove non-asbestos particles (490). Retention efficiencies for sampling urban aerosols were low for paper filters ( 4 0 ) .Filter efficiency data were presented for ultrafine polydisperse fibers ( 2 3 0 ) ,for several common membrane and Teflon filters (350),and for Nuclepore filters (470).Sulfuric acid mist was efficiently collected on glass fiber filters but, a t low loadings, part evaporated and, at high loadings, part flowed through the filter (510).The best types of glass and quartz fiber filters with low blanks for collecting metal and acid aerosols ( 1 6 0 ) ,and of membrane filters for total weight and IR silica analysis of coal mine dust (370)were reported. High volume sampler filters standing inactive for 5-6 days in a shelter gained significant weight due to windborne deposition of particles ( 6 0 , 7 0 ) . Reviews on particle size analysis dealt with sampling (1401, particle size representations (190,320, 3 3 0 ) ,size separation method (300),limits and resolution ( 3 1 0 ) ,sedimentation in a centrifugal field ( 5 4 0 ) ,and surface sorption (250). Theoretical and experimental studies were made of the performance and parameters of the laminar flow aerosol impactor (150, 390, 4 0 0 ) , and of round jet impactors (460). Relative humidity (530)and inlet design (290,520)affected impaction and bounce. Multiple polystyrene particles produced erroneous calibrations (200). Aerosol concentrations and size distributions were determined by optical methods ( 9 0 ) ,by the small ion superposition effect ( 2 7 0 ) ,by absorption of a laser beam ( 1 2 0 ) ,and by measuring particle velocities in an acoustic field with a laser Doppler velocimeter ( 2 2 0 ) .Ellipsoidal parameters characterizing elongated shapes were evaluated from microphotographs (210).Very small particles were measured by electron microscopy (420).Number size distributions of atmospheric aerosols were determined with a four-channel integrating nephelometer, a two-channel optical particle counter, and a condensation nucleus counter (17 0 ) .Diameters of fog droplets were determined by photography of their diffraction patterns in a polarized laser beam (260).Particle diameters based on terminal settling velocities agreed with results by electron microscopy (500). Masses of single particles were determined by impacting them on a thin elastomer membrane and measuring its vibration with an interferometer ( 1 8 0 ) .A cloud chamber instrument determined number and size distributions of condensation nuclei ( 4 3 0 ) . Cyclone-filter assemblies demonstrated bimodal distributions of sizes of suspended particulates in New York City, and the fractions were analyzed for lead, copper, and manganese ( 2 0 ) .Impactors collected particles in the stratosphere for size and chemical analyses (300). Size separation by diffusion was followed by analysis (380).Respirable coal dust was determined by a new Tyndallometer ( 5 0 ) . Statistical errors of grain size analysis were related to sample volumes ( 4 8 0 ) . The theory, performance, and applications of beta radiation ( 8 0 , 340, 4 4 0 ) and piezoelectric crystal sensors ( 1 0 0 ) to determine aerosol mass concentrations were reviewed and investigated. An on-line beta attenuation mass monitor used a two-stage (impactor-filter) sampler ( 3 6 0 ) ,and another monitor counted single particles by flame ionization (10).A new portable mass monitor precipitated particles electro2R
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ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
statically on a piezoelectric crystal (450). A high volume sampler was modified for use in the Antarctic (410).Results for total suspended particulate were compared for three different methods: the integrating nephelometer, the reflectometric method, and gravimetrically after collection on cellulose filters (280).The results using the high volume method were compared with those of the personal monitoring method using a membrane filter ( I I D ) ,and of three other methods: light scattering, beta-ray absorption, and measurement of ionization currents caused by deposition of ions on particles (240). Inorganic Particulates. Asbestos sampling with Nuclepore filters was found to give higher microscopic counts than with three other types (52E).Electron microscopy identified six recognized mineral types of asbestos (14E,33E),and was used to measure the fibers filtered from air or water (6E,13E). Examination was facilitated by aligning fibers in a magnetic field (59E),and by dispersion staining (39E)or differential dye adsorption (38E)techniques. An infrared technique determined sub-milligram amounts of asbestos (7E).Difficulties in the analytical techniques for free silica were reviewed (3E, 4E, 28E);a rapid x-ray diffraction method for airborne dust from sand blasting operations ( 2 E ) and a chemical micromethod (18E)were developed. Occurrence of trace metals in the environment and their determination by atomic absorption spectrometry (AA) was reviewed (43E).Preparation of homogeneous dust samples for comparing analytical results was described (23E).Lead was analyzed by flameless AA after collection in a porous graphite cup (34E),on a millipore filter (42E),and on porous polymer filters with 10 other metals (9E).A graphite disk and carbon bed sampler separated particulate and gaseous lead compounds (49E). Zinc and cadmium in environmental samples were determined by spectroscopy using a radiofrequency furnace (56E). Carbon furnace AA determined 15 metals in samples at a steelworks (44E).Metals in dust around power plants (53E),a lead smelter (19E),and ore concentration dump (5E) were studied. Spark excited emission spectroscopy showed 8%higher lead contents than AA for the National Air Surveillance Network samples (50E),but different sectiohs of the same filter did not differ with each other [cf. (5B)l. Variable losses of arsenic were found (60E) even with low temperature ashing of particulate samples. Multielement analyses by neutron activation, emission spectrometry, and x-ray fluorescence were useful to identify pollutant sources. The distribution by particle size and significance of lead, bromine, and chlorine in urban-industrial aerosols were determined (45E). Important parameters of neutron-activation procedures applicable to over 40 elements were reviewed (8E). Details for routine determinations of many elements in atmospheric particulates were given (31E, 46E). Lead was determined by proton activation analyses (16E).Emission spectrometry was used to analyze for metals in airborne particulate matter collected on glass fiber (12E, 55E) and silver (54E)Filters. Multielement x-ray fluorescence procedures for air pollutants were described ( I I E ,29E),and corrections for self-absorption by the sample were given ( I E , 15E). Radioactive isotopes were determined by gamma-ray spectrometry (62E). Gas chromatographic methods for analysis of atmospheric aerosols utilized chelation with trifluoroacetylacetone (TFA) for beryllium, aluminum, and chromium (63E),and for iron (40E),and were also applied to free sulfur-containing acid (47E) and to selenium after complexing it with 4-chloro-ophenylenediamine (41E).Specific ion electrodes determined fluoride (24E)and nitrate (21E).Analytical methodology for sulfate aerosols was reviewed ( I 7E, 57E);flame photometric (25E,27E, 36E, 48E),ion specific electrode (20E),colorimetric (26E, 58E, 60E), and thermometric (22E) procedures were applied to pyrolyzed or treated samples. Spectrophotometric methods determined chromium(V1) (30E) and tellurium (37E)in industrial atmospheres. Elemental carbon was determined in fly ash (51E) and high volume filter samples (32E). Measurement of low vapor pressures of organic pollutants by thermal techniques was reviewed (10E). Organic Particulates. Polynuclear compounds were extracted from filter samples, separated by thin-layer chromatography and the benzo[a]pyrene (BaP) spot was determined by fluorescence spectrometry (15F, 21F). Recovery became poorer for small samples (6F). Polycyclic quinones were de-
Bernard E. Saltrman is Professor of Environmental Health, Department of Environmental Health, University of Cincinnati, and Head of its Division of Environmental Hygiene. He served in varied assignments as an Officer in the US. Public Health Service from 1941 to 1967, when he retired as a Sanitary Engineer Director. As Deputy Chief of the Chemical Research and Development Section. National Air Pollution Control Administration (now EPA) from 1962-1967, he organized its first analytical methods standardization activities. From 1945 to 1962, he was with the Division of Occupational Health as an industrial hygiene chemist in Bethesda and Cincinnati, and as Chief of Laboratory in Salt Lake City; he was in charge of the West Virginia State Water and Sewage Laboratory in 1943-1944, and was a sanitary engineer in 19411943 in Massachusetts and New York. Author of over 80 publications, he developed many widely used analytical procedures. He received his Ph.D. in chemical engineering from the University of Cincinnati, is a licensed professional engineer, State of Ohio, and is certified by the American Board of Industrial Hygiene. He was a former Chairman of the Intersociety Committee on Methods of Air Sampling and Analysis (which has representatives of 13 professional societies including ACS), and is a member of The American Chemical Society, Air Pollution Control Association, American Industrial Hygiene Association, American Conference of Governmental Industrial Hygienists, American Society for Testing and Materials, Association of Official Analytical Chemists, Sigma XI, Tau Beta Pi, and Phi Lambda Upsilon. He has served as a consultant to the National Institute for Occupational Safety and Health, Occupational Safety and Health Administration, U S . Army Environmental Hygiene Agency, Tennessee Valley Authority, and the National Academy of Sciences.
William R. Burg is an Assistant Professor of Environmental Health, Department of Environmental Health at the University of Cincinnati. He received his Ph.D. in Chemistry from Kent State University. After teaching physical and analytical chemistry for five years, he was a postdoctoral fellow at the University of Cincinnati conducting research in analytical methodology for air contaminants. He is a member of the American Industrial Hygiene Association (and of its Analytical Chemistry Committee), Ti American Chemical Society, American Conference of,Governmental IndLstrial Hygienists and s certified in Comprehensive Practice by the American Board of hdustrialt Hygiene. His research interests are in analytical methods, kinetics, and the fate of air pollutants.
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termined in the same manner (22F).In a similar procedure, the initial step was to vacuum sublime the organic compounds from the dust (19F). Also employed were a gas chromatographic procedure with a gas phase fluorescent detector (20F), or with a mass spectrometer (3F, I6F), and high pressure liquid chromatography coupled with fluorescence techniques (8F). Aromatic nitrogen heterocyclics in air samples were analyzed using a silver impregnated adsorbent for high-speed liquid chromatography (9F). High volume samples collected throughout Los Angeles County were analyzed for 14 polycyclic aromatic hydrocarbons and showed seasonal and area variations (IOF).The organic constituents of samples from six geographic regions (14F),and differences in samples from urban and clean air regions were reported (13F). A series of solvents were used to extract components from atmospheric particulate matter and elemental carbon determined in the extracts ( I F , I2F), or infrared spectrometric measurements were made (4F).Particulates were also characterized by elemental (CHN) composition (17F)and mass spectra (23F)to identify their sources. The effect of sampling flow rates on the nonvolatile fraction was studied with infrared techniques (5F).The composition varied with wind direction, since labile hydrocarbons in organic particulates from remote sources were lost (7F).The methods for the determination of oil mist were reviewed (24F). An IR procedure determined styrene-butadiene rubber extracted from tire dust collected on filters (2F).A new method determined the optical properties of soot particles by using a tunable laser ( I I F ) . The size distributions of airborne coal dust were determined by optical particle counters (18F).
INORGANIC GASES AND VAPORS
Carbon Monoxide. Nine categories of methods for the measurement of carbon monoxide: biological methods, gasometric, oxidation and other chemical methods, gas chromatography, mass spectrometry, infrared analyzers, detector tubes, and electrochemical sensors were reviewed (5G).The electrochemical oxidation of CO at a Teflon-bonded diffusion electrode in one type of sensor was studied ( I G ) . Another electrochemical cell employed metallized membrane electrodes to measure CO a t levels above 10 ppm in the presence of a variety of other gases (3G).A two-layer detector cell improved the stability of a nondispersive infrared analyzer (7'3). Cheap metal oxide semiconductor sensors produced large signals when they adsorbed low concentrations of carbon monoxide, but were not specific (4G).Submicro-levels (
