Environment Simulation for Studying the Effects of Air Pollutants on Computers

This paper describes a study directed towards the laboratory simulation of parameters of the office environment related to air borne gaseous and particulate pollutants and initial operating experience of a particulate test chamber, instrumentation, and control techniques. Also discussed is the design of a simple gaseous test chamber being constructed. Gas dilution procedures, control and general operating approach are described.     

Dust Scrubber Design—A Critique on the State of the Art

Geographic variation in the prevalence of respiratory disease between communities has been used to incriminate air pollution at low concentrations in the production of disease. Though demographic factors and the design and conduct of survey research affect the validity of these observations, there are other complex factors which are often neglected. From several community studies planned or conducted by the authors, illustrations will be given of the effect of the following six frequently neglected factors: the reliability of the air pollution monitoring network; the validity of the air pollution monitoring network; the competing effect of differential migration of population; the competing effect of occupational pollution of members of the population; the competing effect of socioeconomic factors; and the competing effect of personal air pollution—tobacco smoking.     

The Survival of Airborne Serratia marcescens in Urban Concentrations of Sulfur Dioxide

Aerosols of Serratia marcescens ATCC 274 were suspended in a 709L rotating drum at 20 ± 1 °C and high to mid-range relative humidities. At specified times after bacterial aerosolization, sulfur dioxide was added to concentrations of 2.5, or 5 mg/m³. Viable cell decay rate constants, in control aerosols without added sulfur dioxide, increased rapidly from near 100% to 60% RH in the first hour (termed: young aerosol) of suspension, and from a minimum rate constant at 80% in the succeeding four hours (termed: old aerosol).Upon addition of sulfur dioxide to a cloud of S. marcescens, generally, viable cell decay rate constants increased further. One exception was at 80% relative humidity where maximum resistance to SO₂ accelerated death was observed for old aerosols. Cells in young aerosols were particularly sensitive to SO₂ addition at mid-range humidities, while in older aerosols the cells were insensitive to up to 5 mg SO₂/m³ introduced at high RH; but were up to 10 times more sensitive than cells in young aerosols to a given increase (from 2.5 to 5 mg/m³) in SO₂ concentration at mid-range humidities.     

Determination of Oxides of Nitrogen in Combustion Effluents with a Nitrate Ion Selective Electrode

The nitrate ion selective electrode was investigated as an alternative approach to the present colorimetric determination of nitrate resulting from oxidative absorption of nitrogen oxides from combustion effluents. The electrode offers advantages of speed and relatively simple experimental procedure. Replicate measurements of 10^?4–10^?2M nitric acid solutions using bracketing standards show that the electrode approach is capable of good precision (coefficient of variation = ±4%). Comparison of a method utilizing the nitrate electrode with the more laborious phenol disulfonic acid method for the measurement of nitrogen oxides in both oil and gas fired combustion effluents showed agreement within 4% of the mean even in the presence of high levels of SO₂. The correlation coefficient found for PDS vs nitrate electrode is 0.987.     

Honorary Memberships

Honorary Memberships are conferred by the Air Pollution Control Association on persons of widely recognized eminence in some part of the field of air pollution control or who have rendered especially meritorious service to the Association. Honorary Memberships were awarded this year to Dr. Leonard Greenburg and Mr. Milton Reizenstein, both past presidents of APCA.     

Emission Control in Coking Operations By Use of Stage Charging

At the Clairton Coke Works of the United States Steel Corporation (the world’s largest coke plant), with coal charges of about 30,000 net tons per day, a system designated as “stage charging” has been developed for charging coal into the coke oven chamber without emissions to the atmosphere. The principles of the system are based on controlled sequential flow of the coal from the charging hoppers, during which the oven chamber is maintained under a very slight negative pressure condition by use of steam aspiration in the offtakes for on-the-main charging. The techniques are basic but require knowledge of the coal characteristics, adequate and properly maintained aspirating systems, including clean offtake piping, control of coal volume in the individual hoppers, and last, and probably most important, adherence by the operating crew to specific charging and leveling practices.