Automotive Exhaust Emission Levels by Geographic Area and Vehicle Make A Nationwide Survey

Gross average automotive exhaust emissions data collected by the Atlantic Richfield Clean Air Caravan during the summer of 1970 showed only slight geographical variations when the specific makes were ignored. When considering specific makes, significant differences were found on an average emissions basis. Vehicle population—emission distributions showed wide variations in the 50% population levels and in the percent of vehicles with emissions greater than specified values. Hydrocarbon (HC) and carbon monoxide (CO) data are given on a gross basis for the 1970, 1968-69, 1966-67, and pre-1966 model year group vehicles. Average HC and CO emissions and vehicle population-Idle emissions distribution curves are included for specific make vehicles in selected areas.     

Emissions from Slash Burning and the Influence of Flame Retardant Chemicals

Pollutants sampled during the burning of 30 lb ponderosa pine fuel beds yielded emission factors for CO, hydrocarbon gases, and par-ticulate matter of 146, 8.4, and 9.1 lb/ton of fuel, respectively. When similar beds were treated with diammonium phosphate flame retardant, these factors increased to 166, 11.7, and 19.3 lb/ton of fuel, respectively.

Gas chromatographic analysis of hydrocarbon gases showed that 15-40% of this material was composed of methane and eth-ylene. Ethane and acetylene were the next most abundant materials, with photochemically important materials constituting minor portions of this gaseous component. Fuel beds treated with flame retardant produced more oiefins, and this production lasted throughout the smoldering phase of burning.

These tests showed that the smoldering phase of combustion is of major importance to air pollutant production during slash burning. The initial 80% of the fuel burned accounted for only 20-30% of HC and CO emissions. This suggests that a rapid mop-up of slash burns could substantially reduce air pollutant production.     

Stack Sampling of Hygroscopic Particulates In an Entrained Water Environment

Reference methods for the determination of mercury emissions from stationary sources typically include collection of mercury by solutions which are acidic and oxidizing. In the presence of high levels of SO₂ the oxidizing capacity of these absorbing solutions will be degraded and the collection efficiency for mercury compromised. This seriously limits the usefulness of the reference methods as they apply to the mining and smelting industries. In the present work peroxide is used to remove SO₂ and acidic permanganate is used to collect mercury. At a mean sampling rate of 10 L/min concentrations of at least 12 mg/m³ mercury can be satisfactorily collected in the presence of up to 20,000 ppm SO₂.     

Infrared Photography as an Air Pollution Surveillance Instrument

Remote sensing is an extremely new science which developed from World War II technology. At that time, infrared sensitive film (false color) was used to detect such things as troop movements and camouflaged war materials. In essence, the film displayed a color contrast between the artificial and organic vegetation.     

Objective Evaluation of Emergency Plans for Oxidant Control

Emergency plans for oxidant controls provide the basis for taking preventive action to protect public health. Historic oxidant data (1970 to Sept. 1974) from the South Coast Air Basin (SCAB), were evaluated to assess episode characteristics in an area where emergency strategies are most likely to be enforced. These findings, together with an objective study of a test case episode (June 1974) using a photochemical air quality simulation model, suggest that the currently conceived emergency plans for oxidant control are unlikely to be effective. It is concluded that, because of the chemical and mefeorofogfcal complexities of the episodes, they are extremely difficult both to predict and concurrently to control over their short-lived duration.     

Some Heavy-Metal Pollutants in the Air of Naples

ABSTRACT

In this paper, assumptions regarding future land use as a key uncertainty is considered and its impact on risk analysis for contaminated sites is assessed. Risks are assessed for two land use scenarios (current-use industrial and future-use residential) using probabilistic models that incorporate uncertainty and variability in the exposure parameters. Residual risks are calculated for both industrial and residential cleanup standards. A Superfund site in northern California is considered.

In general, for the unremediated case, the future-use residential scenarios produce larger risks (1 to 3 orders of magnitude) than current- (continued) use industrial scenarios. For the Superfund site studied, the residual risks calculated for the remedy selected was not sufficiently protective of future-use residents in that it did not meet .S. Environmental Protection Agency (EPA) risk goals, but was protective of current-use workers, even though the cleanup criteria were based on residential use. Alternative risk management practices, such as deed restrictions, can be used in such cases.     

A Method for Predicting the Effective Volume Resistivity of a Sodium Depleted Fly Ash Layer

Research has been conducted to develop a technique for predicting the effective volume resistivity of a fly ash layer that has been exposed to circumstances leading to a hot-side precipitator problem known as sodium depletion. Eight fly ashes, representing a major portion of U.S. coals, were evaluated by subjecting 0.5 cm ash layers to a continuously applied voltage gradient of 4 kV/cm for periods of time up to 35 days at a temperature of 350°C (662°F). Resistivity was determined at 350°C before the test started and after the long period of applied voltage used to create the sodium depleted situation. In this condition, resistivity was also determined at 280°C (536°F) for an average electric field Intensity of 4 kV/cm and immediately prior to breakdown. This experimental method can be used with any ash sample to estimate resistivity In a sodium depleted condition. But in addition, a correlation resulting from these resistivity data has been developed. This correlation Is combined with an existing technique for predicting resistivity to produce a method for calculating the expected ash layer resistivity after sodium depletion has occurred.     

Evaluation of RAM Model for Cleveland,Ohio, Part II

Coal combustion is the primary contributor to atmospheric pollution in China, especially so In big cities. Particulate matter and sulfur dioxide are the two main pollutants worthy of attention. Concentration of suspended particles is usually higher in northern cities than in southern cities and higher in winter than in summer. In the case of sulfur dioxide, concentrations are high in the heating season (wintertime) in northern cities, but also in some of the cities in the southwest part of China. Rainfall with pH less than 5.6 occurs mostly to the south of the Yangtze River, especially so in the cities of Chongqing and Gueiyang, and their neighboring areas, and also In the southwest part of China. No acid rain, however, has been found in Beijing and Tianjin. Although the formation of acid rain can thus be thought of as dependent on the presence of enough sulfur dioxide, other factors such as airborne particles and ammonia also play an important role. The difference is, therefore, explained and theorem postulated with supporting data. Ways of abating atmospheric pollution are, in essence, related to improved coal burning; some simple methods are suggested for nationwide control options.