Dry Removal of Gaseous Fluorine Pollutants

The conservation equations governing buoyant plume rise are solved for the case of non-uniform wind conditions. A power law is selected to represent the actual wind profile. Analytical solutions are presented both for uniformly stable and neutral atmospheric conditions. These solutions are shown to be of the same form as those obtained in the simpler uniform case but with the plume rise now depending explicitly on the wind speed shear. A sensitivity analysis of the effects on plume rise of typical variation in wind shear and entrainment reveals that the two quantities have an almost equal effect therefore justifying the use of the present model. To simplify computations a “uniform wind” is introduced such that when used in conjunction with Briggs' equations the results become consistent with those of the present theory.     

Gaseous Sulfur Pollutants from Urban and Natural Sources

Major aspects of the circulation through the atmospheric environment of sulfur pollutants have been estimated, including source magnitudes, residual atmospheric concentrations, and scavenging processes. The compounds considered include SO₂ and H₂S, as well as sulfates. One-third of the sulfur reaching the atmosphere comes from pollutant sources, mainly as SO₂. Within the atmosphere there is a net transfer of sulfur from land to ocean areas. Pollutant sources annually amount to 73 × 10⁶ tons as sulfur while natural sources amount to 142 × 10⁶ tons, mainly as H₂S and sulfate sea spray. More than two thirds of the natural and pollutant sulfur emissions occur in the northern hemisphere. When only pollutant emissions are considered, 93 per cent occur in the northern hemisphere.     

Source Inventory IBM System for Particulate and Gaseous Pollutants

A source inventory IBM system of air pollutants is described which makes use of an existing IBM card index-registration system in an established air pollution control district and which employs efficient utilization of engineering time, including computer services, to establish and maintain current a detailed source inventory of point sources of emissions.     

Characteristics of regional nucleation events in urban East St. Louis

Continuous measurements of aerosol size distributions (3 nm–2 μm) were carried out over a 26 month period (1 April 2001–31 May 2003; 650 days with valid data) in urban East St. Louis, IL, as a part of the US Environmental Protection Agency's Supersite program. This paper analyzes data for the 155 days on which “regional nucleation events” were observed during this study. Such events were observed during every month of the study except January 2003. We observed some differences, however, between events in the summer (defined here as April–September) and winter (December–February). Regional nucleation events were observed more frequently in summer months (36±13% of days) than in winter (8±7%), and nucleated particles grew faster in the summer (6.7±4.8 nm h⁻¹) than in winter (1.8±1.9 nm h⁻¹). The daily maximum in the number concentration of nanoparticles formed by nucleation (4.8±3.5×10⁴ cm⁻³) was highly variable and showed no clear seasonal dependence. Particle formation increased particle concentrations by an average factor of 3.1±2.8. Maximum daily rates of 3 nm particle production (17±20 cm⁻³ s⁻¹) were also highly variable and without a clear seasonal dependence. During these events, particle formation rates were typically near their maxima at 08:00–09:00 a.m., but particle production sometimes persisted at diminishing rates until late in the afternoon (15:00–16:00 p.m.).     

Public Awareness and Concern with Air Pollution in the St. Louis Metropolitan Area

The public attitudes survey involving St. Louis City, St. Louis County, and Madison and St. Clair Counties, Illinois, was completed and published in the fall of 1964. A total of 1002 respondents gave needed information for the development of an acceptable abatement program. Substantial proportions from the study area expressed the view that they have had some negative reaction to the quality of the air. These respondents indicated that air pollution meant, primarily, odor and smoke with residents of some localities indicating other significant elements. The interviewed persons felt that factories and businesses were the prime causal agents in the existence of air pollution. Over 90 percent of all respondents felt that some governmental agency should do something about air pollution in the St. Louis area, with some bi-state metropolitan agency being the principal choice. The residents also expressed a willingness to pay minimal tax support for such a program. Indications as to the significance of air pollution in a general problems context, difference in attitudes between sub-sections of the study area, and more detailed analysis of the problem, its causes, and possible cures are contained in the study r     

A Wind Tunnel Study of Gaseous Pollutants in City Street Canyons

Steady state mean concentrations of tracer gas were measured in a 400:1 scale model of an idealized city with variable geometry placed within a wind tunnel at various orientations to the mean flow for a free stream velocity of 6.8 ft/sec. The tracer gas was released from two parallel line sources to simulate lanes of traffic in an effort to quantify the persistence of pollution as well as the mean values realized at street levels. An aerodynamically rough turbulent boundary layer of neutral thermal stratification was employed to simulate the atmosphere. Values of concentration measured in the model city were converted to prototype concentrations in ppm and compared to National Ambient Air Quality Standards. It was shown that single isolated structures may cause favorable mixing of pollution downwind but very high concentrations exist in the immediate leeward vicinity of the building. Two favorable geometries for city blocks tested were found to reduce pedestrian exposure to pollution both near heavy traffic congestion and downwind. It was concluded that the pollutant dilution was controlled by the mean flow rather than by turbulent diffusion and that the lateral spread of the plume was slight as one proceeded downwind of the line source. The combination of favorable geometry and higher dilution velocities may bring pollution levels down to existing Air Quality Standards. The body of information presented in this paper should interest city planners and air quality monitoring personnel, as well as those researchers attempting to study and model flow in city street canyons. It provides order of magnitude estimates on pedestrian and office worker exposure to pollutants under a wide range of conditions.     

Absorption of Gaseous Air Pollutants By a Standardized Plant Canopy

Concentration profiles for hydrogen fluoride(HF), sulfur dioxide(SO₂), ozone (O₃), nitrogen dioxide(NO₂), and nitric oxide(NO) generated in a standardized alfalfa canopy are presented. Wind, light, temperature, and carbon dioxide(CO₂) profiles, canopy pollutant uptake rates, and canopy structural data are also given. Canopy pollutant concentration profile characteristics were studied to evaluate the relative potentials for major air pollutants to penetrate into canopies. The study was conducted in an environmental growth chamber equipped to control automatically environmental conditions and monitor continuously gas exchange rates. HF, SO₂, and NO₂ profiles suggested that these gases were removed efficiently by the upper portion of the canopy as well as by the immediate subsurface vegetation. The steady state HF profile showed the greatest displacement within the canopy. The NO profile was displaced the least. The uptake rate of NO by plants was apparently too slow in comparison with gas transport and mixing within the canopy to affect the internal profile substantially. O₃ appeared to be readily deposited on the surface tissues, but the deeper tissues in the canopy had less effect on the concentration profile. Data are also presented to show the relationship between NO₂ concentration within the canopy and changes in the air concentration above the vegetation. The results indicated that gas transport between the atmosphere and canopy interior was rapid. The data presented should be of current interest to agriculturists, researchers, administrators, and environmental planners concerned with effects of air pollutants on plants and on the fate of pollutants in the microenvironment.     

The Evolution of Visibility Deterioration and Aerosol Spectra in the St. Louis Urban Plume

Under the auspices of Project METROMEX, studies of visibility de-teoration downwind of St. Louis were conducted during July-August 1974-1975. Estimates of horizontal visual range, standard meteorological data, and aerosol characteristics within the mixing layer were acquired upwind, over, and downwind of the metropolitan area by means of airborne transects. Aerosol number, surface, and volume distributions for particles between 0.025-2.5 µm were generated from the airborne measurement of Aitken nucleus concentrations, cloud condensation nuclei, and aerosols detected in situ with optical probes. Visibility reduction amounting to 50% of prevailing regional upwind visibilities consistently occurs at a distance corresponding to 2-3 hours travel time downwind for an air parcel moving with the mean transport wind. The regions of visibility minimum do not coincide with locations of maximum Aitken nucleus concentrations, but rather correspond in space and time to increased values of cloud condensation nuclei and increased numbers of particles in the 0.1-2.5 µm diameter range. Comparisons of observed aerosol evolution with similar laboratory studies suggest that most of the light scattering aerosols are of secondary origin.     

Day of the week variations of photochemical pollutants in the St. Louis area

As part of the Environmental Protection Agency's Regional Air Pollution Study (RAPS) a network of 25 stations continuously recorded aeromatic data in the Greater St. Louis area. Various photochemical pollutants (O₃, NO, NO₂ and total hydrocarbons) and some selected meteorological variables (wind speed, temperature, and solar radiation) were analyzed with respect to the day of the week using 11 months of data collected during the warm months of the year — periods during which high ozone concentrations were common in St. Louis. The results reveal that the sign (±) of the workday to Sunday differences in the concentration of ozone depends to a large extent on the distance of the measurement from the major emission area of the metropolitan area of St. Louis. The data suggest that this is due to the impact of nitric oxide on the ambient ozone concentrations. This appears to offer at least a partial explanation for some of the contrasting results reported by various investigators regarding the differences in ozone concentrations between weekends and weekdays.     

Short-Term Effects of Gaseous Pollutants on Cause-Specific Mortality in Wuhan,China

Abstract

In Asia, limited studies have been published on the association between daily mortality and gaseous pollutants of nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂). Our previous studies in Wuhan, China, demonstrated long-term air pollution effects. However, no study has been conducted to determine mortality effects of air pollution in this region. This study was to determine the acute mortality effects of the gaseous pollutants in Wuhan, a city with 7.5 million permanent residents during the period from 2000 to 2004. There are approximately 4.5 million residents in Wuhan who live in the city’s core area of 201 km², where air pollution levels are highest, and pollution ranges are wider than the majority of the cities in the published literature. We used the generalized additive model to analyze pollution, mortality, and covariate data. We found consistent NO₂effects on mortality with the strongest effects on the same day. Every 10-μg/m³increase in NO₂daily concentration on the same day was associated with an increase in nonaccidental (1.43%; 95% confidence interval [CI]: 0.87–1.99%), cardiovascular (1.65%; 95% CI: 0.87–2.45%), stroke (1.49%; 95% CI: 0.56–2.43%), cardiac (1.77%; 95% CI: 0.44–3.12%), respiratory (2.23%; 95% CI: 0.52–3.96%), and cardiopulmonary mortality (1.60%; 95% CI: 0.85– 2.35%). These effects were stronger among the elderly than among the young. Formal examination of exposure-response curves suggests no-threshold linear relationships between daily mortality and NO₂, where the NO₂concentrations ranged from 19.2 to 127.4 μg/m³. SO₂and O₃were not associated with daily mortality. The exposure-response relationships demonstrated heterogeneity, with some curves showing nonlinear relationships for SO₂and O₃. We conclude that there is consistent evidence of acute effects of NO₂on mortality and suggest that a no-threshold linear relationship exists between NO₂and mortality.     

Concentration of Atmospheric Pollutants in the Gaseous Emissions of Medical Waste Incinerators

ABSTRACT

The purpose of this paper is to quantify the production of medical waste from a general hospital and to evaluate the atmospheric pollutant concentrations in gaseous emissions associated with its incineration. A 3.8 kg (bed.day)^-1 production of medical waste was estimated for 1998; its incineration is related with an ash production of 0.3-0.4 kg (bed.day)^-1. The concentrations of atmospheric pollutants were estimated using emission factors, comparing the effluents with and without control of atmospheric pollutants. The calculated concentrations were compared with the emission limits established by Portuguese legislation. The results indicate that, if there is no control of atmospheric pollutants, their concentrations exceed the established limits. This is observed even if correct operation and maintenance procedures are used. The emission concentrations of dioxins are higher than the Portuguese emission limit, which is particularly worrying due to the high toxicity of some of these compounds. Generally, it is possible to reduce pollutant concentrations if appropriate control equipment is used. The conclusions obtained clearly justify the great concern regarding air pollution associated with medical waste incinerators currently operating in Portugal.     

Effects of Gaseous Air Pollutants on Gastric Secreto-Motor Activities in the Rat

A study was initiated to ascertain whether gaseous air pollutants can influence gastric secreto-motor activities. The investigation was conducted to determine the effect of various exposures to S0₂, N0₂, CO, and 0₃ on gastric motor activity of the conscious unrestrained rat by means of a chronic intragastric bajloon. Tfie effects produced upon gastric secretory volume and total titratable acid secretion produced by these gases were also studied in rats which were pylorus-ligated subsequent to exposure. Rats exposed to 1 ppm S0₂ for 5 days, 60 ppm CO for 2 hours, 0.5 ppm N0₂ for 2 hours, or 0.25 ppm 0₃ for 2 hours showed no change while there was gastric inhibition at 300 ppm S0₂ for 2 hours, 1400 ppm CO for 1 hour, 26 ppm N0₂ for 2 hours and 1.5 ppm 0₃ for 2 hours. In most instances following chamber flushing recovery was complete within minutes. To evaluate the site and nature of stimulation, rats were also exposed to oil of mustard, benzaldehyde, hydrogen peroxide, amyl acetate, and “Old Spice” after sh ave lotion. Saturated dental paper points were introduced without obstruction into tracheal and retro-nasal cannulae. Oil of mustard but not benzaldehyde or amyl acetate inhibited gastric motility only when applied to the trachea. In general, the drop in activity was immediate and proportional to the degree of exposure. Nasal irritation was ineffective in eliciting the response. The experimental results lead to the following conclusions: 1) Toxic levels of these gases are associated with an inhibition of gastric motility that is not produced by .exposure of the nasal passages alone to the gases. 2) Toxic levels of these gases produced no demonstrable effect upon either total gastric acid secretion or total secretory volume. These findings tend to confirm earlier observations of an association between exposure to toxic concentrations of S0₂ and loss of gastric tone in the rodent stomach.     

Locating the St. Louis urban plume at 80 and 120 km and some of its characteristics

The feasibility of locating the urban plume of a moderately large urban area, as far as 120 km downwind, is shown. The method utilizes a single engine aircraft and aerosol instrumentation. A summary of the data obtained from 34 flights, during an 8-month period, is presented and the problems involved in interpreting the data are discussed. These difficulties include nonuniform background levels outside the plume, changing relative humidity, low wind speeds and stable atmospheric layers. The plume was characterized by concentrations of small particles (0.15 < r < 0.3 μm) ca. 1.5 times that in background air and concentrations of large particles (0.3 < r < 1.3 μm) usually greater than twice that in the background. The ratio of the concentrations of small particles to large particles in the plume was about one-half of that in the background.     

Heavy metals in urban soils of East St. Louis, IL. Part II: Leaching characteristics and modeling

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produced organic and inorganic chemicals, and petroleum refineries. Following a gross assessment of heavy metals in the community soils (see Part I of this two-part series), leaching tests were performed on specific soils to elucidate heavy metal-associated mineral fractions and general leachability. Leaching experiments, including the Toxicity Characteristic Leaching Procedure (TLCP) and column tests, and sequential extractions, illustrated the low leachability of metals in East St. Louis soils. The column leachate results were modeled using a formulation developed for fly ash leaching. The importance of instantaneous dissolution was evident from the model. By incorporating desorption/adsorption terms into the source term, the model was adapted very well to the time-dependent heavy metal leachate concentrations. The results demonstrate the utility of a simple model to describe heavy metal leaching from contaminated soils.     

Comparison of RAM model estimates with 1976 St. Louis RAPS measurements of sulfur dioxide

Comparisons of model estimates from the model RAM with SO₂ measurements from 13 Regional Air Pollution Study sites in St. Louis for the year 1976 were made with emphasis on 2nd highest concentrations for the 1-h, 3-h and 24-h averaging times, and also the top 5% of the distribution for 24-h concentrations. Although there is considerable scatter in the comparison of the 2nd highest concentrations, only 9 of 39 data points are outside the bounds of a factor of two and no overall bias is seen, although as the averaging time increases there is more underestimation by the model. Exponential distribution fit the top 5 % of the 24-h concentration distributions for all stations for both estimated and measured concentrations. The distributions for estimated and measured concentrations were judged to match at eight of the thirteen sites.     

Effects of Acid Rain and Gaseous Pollutants on Forest Productivity: A Regional Scale Approach

Increased industrialization of the eastern U.S. over the past several decades has led to regional scale buildup of atmospheric pollutants and concern over possible losses in forest productivity within this region. This paper describes the rationale, methodology, and some preliminary results of a large regional scale study designed to characterize and quantify forest growth impacts attributable to atmospheric stress from both gaseous pollutants and acid rainfall. This research employs a variety of dendroecological techniques to examine the influence of climatic factors, tree age, soil type, competition, and air pollution on tree growth. This broadly collaborative project involves twelve government and university research stations working with a common experimental protocol to examine ≥50 year ringwidth series from approximately 6000 trees distributed over an area extending from Maine to North Carolina and as far west as Missouri. Principal objectives of this research are to determine whether a systematic pattern of decreasing forest growth has occurred, to define its temporal, spatial, and quantitative characteristics, to determine its relationship to differences in soil quality and tree species, and to evaluate its correlation with present and past indices of atmospheric deposition.