Major Gaseous Pollutants Research Articles

Modifications of Phleum pratense Grass Pollen Allergens following Artificial Exposure to Gaseous Air Pollutants (O3, NO2, SO2)

Background: Air pollution is frequently proposed as a potential cause of the increased incidence of allergy in industrialised countries. Our objective was to investigate the impact of the major gaseous air pollutants on grass pollen allergens. Methods: Timothy grass pollen was exposed to ozone (O₃), nitrogen dioxide (NO₂) and sulphur dioxide (SO₂) alone or in combination. Allergen contents were analysed by 2-dimensional immunoblot using grass pollen-sensitive patient sera. Results: For O₃-treated pollen, immunoblotting showed an acidification of allergens Phl p 1b, Phl p 4, Phl p 5 and Phl p 6 and an IgE recognition decrease in Phl p 1, Phl p 2, Phl p 6 and Phl p 13. NO₂ exposure induced a decrease in Phl p 2, Phl p 5b and Phl p 6 recognition, and SO₂ treatment induced a decrease in Phl p 2, Phl p 6 and Phl p 13 recognition. Moreover, samples treated with a mix of NO₂/O₃ or NO₂/SO₂ showed a higher decrease in allergen content, compared with samples treated with only one pollutant. The O₃ acidification was also observed with the NO₂/O₃ mix. Conclusion: Exposure of pollen to gaseous pollutants induced a decrease in allergen detection in pollen extracts. This decrease could be due to a mechanical loss of allergens from the altered pollen grains and/or post-translational modifications affecting allergen recognition by IgE.

Mercury Oxidization in Dielectric Barrier Discharge Plasma System

The pronounced volatility of elemental mercury (Hg0) and some of its compounds, coupled with their extreme toxicity, makes these substances extremely hazardous. Conversion of Hg0 to HgO would significantly enhance mercury removal from flue gases. This investigation is focused on studying the effect of some of the constituents such as O2, H2O, CO2, and NOx present in flue gases on elemental mercury oxidation in a dielectric barrier discharge (DBD) reactor. The results show that Hg vapors (6 ppbv) in a stream of 0.1% O2 and N2 are effectively oxidized at the energy density of up to 114 J/L. Hg conversion of over 80% is achieved when present in a gas mixture of 8% O2, 2% H2O, and 10% CO2 in N2 balance. The presence of NOx enhanced mercury oxidation in the DBD reactor. The oxidation chemistry is discussed. Studies show that Hg can be simultaneously removed along with the other two major pollutants, NOx and SO2, in one DBD reactor followed by a wet scrubber system. This avoids the need of three techniques for the removal of major gaseous pollutants from coal-fired power plants.

An Analysis of Effects of San Diego Wildfire on Ambient Air Quality

The impact of major gaseous and particulate pollutants emitted by the wildfire of October 2003 on ambient air quality and health of San Diego residents before, during, and after the fire are analyzed using data available from the San Diego County Air Pollution Control District and California Air Resources Board. It was found that fine particulate matter (PM) levels exceeded the federal daily 24-hr average standard during the fire. There was a slight increase in some of the gaseous pollutants, such as carbon monoxide, which exceeded federal standards. Ozone (O3) precursors, such as total hydrocarbons and methane gases, experienced elevated concentration during the fire. Fortunately, the absence of sunlight because of the cloud of thick smoke that covered most of the county during the fire appears to have prevented the photochemical conversion of the precursor gases to harmful concentrations of O3. Statistical analysis of the compiled medical surveillance data has been used to establish correlations between pollutant levels in the region and the resultant health problems experienced by the county citizens. The study shows that the increased PM concentration above the federal standard resulted in a significant increase in hospital emergency room visits for asthma, respiratory problems, eye irritation, and smoke inhalation. On the basis of the findings, it is recommended that hospitals and emergency medical facilities engage in pre–event planning that would ensure a rapid response to an impact on the healthcare system as a result of a large wildfire and appropriate agencies engage in the use of all available meteorological forecasting resources, including real–time satellite imaging assets, to accurately forecast air quality and assist firefighting efforts.

Co-combustion performance of poultry wastes and natural gas in the advanced Swirling Fluidized Bed Combustor (SFBC)

Co-combustion of poultry wastes with natural gas in an advanced Swirling Fluidized Bed Combustor (SFBC) has been carried out to investigate the performance of poultry wastes combustion. Wastes burnt were poultry litter, poultry manure and sawdust. This paper presents the effect of three different wastes, excess air ratio, and secondary/total air ratio on the combustion characteristics. These characteristics include temperature distributions, carbon combustion efficiency, major gaseous pollutants emissions and heat recovery efficiency. The results indicate that, with the given moisture and ash contents in wastes, the excess air and the secondary air play important roles in achieving stable combustion. The carbon combustion efficiency could increase by 8–10% when the excess air is increased to 25% with the secondary air being at 20% and having a low injection height. However, the carbon combustion efficiency for the sawdust, which is 92% on average, is much higher than that of the poultry litter and manure, which is 81% and 76% on average, respectively. Differences regarding temperature distribution and pollutants emission were also observed with different combinations of the excess air, the secondary air and the secondary air injection height. The NO x emission was very low even though the materials contain high levels of nitrogen. In addition, the heat recovery efficiency aiming at the commercial use of the SFBC system for the farm industries was also evaluated.

Co-combustion of municipal solid waste and Thai lignite in a fluidized bed

Co-combustion of high moisture municipal solid waste (MSW) and high sulfur Thai lignite in a laboratory scale bubbling fluidized bed has been investigated. This paper presents the effects of the mass fraction of a model MSW in the fuel mixture, as against 100% lignite, on the combustion characteristics that may be inferred from temperature distributions, carbon combustion efficiency and CO and CO 2 concentrations and on the emissions of major gaseous pollutants, including CO, SO 2, NO and N 2O. The influence of excess air and secondary air on those characteristics are also discussed. The results show that within the 40% MSW fraction tested, co-combustion is characterized by enhanced combustion of volatiles in the freeboard, a lower bed temperature and a combustion efficiency drop of up to 8%. Co-combustion either increases or reduces CO emission depending on the percentage of excess air. Reduction of up to 7–18% of SO 2 is observed at the 40% MSW fraction for the range of excess air and secondary air tested. Both NO and N 2O increase slightly with increasing fraction of MSW. Within the range of experimental conditions tested, the optimum condition for co-combustion in view of combustion efficiency and CO, NO and N 2O emissions is: 20% MSW, 40% excess air and 0.2 secondary to total ratio, although the reduction of SO 2 is slightly smaller than at other conditions.

Prediction of gaseous pollutants and heavy metals during fluidized bed incineration of dye sludge

This research provides an equilibrium model for predicting both the emission of gaseous pollutants and the fate of heavy metals during incineration of biologically treated dye sludge in a bench-scale fluidized bed incinerator. Major gaseous pollutants and hazardous trace heavy metals have been also measured under various operating conditions. The predicted values, which were derived by using a thermodynamic equilibrium model, can be used to determine the optimum operating parameters and the risk associated with hazardous waste incineration by means of verifying experimental data. However, prediction of NOx emission using a thermodynamic equilibrium model during incineration of waste was not simple. The reason is that the variation of NOx emission during incineration of waste was affected by the various operating parameters, such as air-fuel ratio(λ T ), primary air factor(λ 1 /λ T ), combustor geometry, method of heat release, and preheating of combustion air. According to the distributions of Cr and Pb simulated by the equilibrium model, all of the Cr in the feed was retained in the ash as the solid phase of Cr2CO3. However, most Pb was retained in the ash during incineration as the solid phase of PbSO4, or heterogeneously deposited onto the fly ash as PbO(g) when the combustion gas becomes cool.

Effects of abscisic acid on ozone tolerance of rice ( Oryza sativa L.) seedlings

Ozone is one of the major gaseous pollutants detrimental to crop growthand metabolism. The objective of this research was to study how ABA amelioratesthe effects of ozone on rice seedlings. Seedlings of two rice cultivars withdifferent sensitivities to ozone (Tainung 67, tolerant; and Taichung Native 1,sensitive) were treated with 400 ppb of ozone or ABA and 400ppb of ozone to determine their effect on growth, stomatalmovement, chlorophyll characteristics, and the activity of antioxidant enzymes.Activities of the enzymes SOD, APOD, GR and POD were significantly higher inthesensitive cultivar, TN 1, than in the tolerant cultivar, TNG 67. Seedlings ofthe sensitive cultivar pretreated with ABA (10 μM) weresignificantly more tolerant of ozone than control seedlings. Pretreatment withABA effectively reduced stomatal conductance and the degree of injury. Abscisicacid also increased ascorbate peroxidase and glutathione reductase activity.Ozone increased peroxidase activity in sensitive seedlings, but ABA decreasedperoxidase activity. The sensitive cultivar had a higher density of stomata onits leaves than the tolerant cultivar. The results suggest that ABA inducedtolerance to ozone may be more associated with its effects on stomatal movementthan on the modulation of antioxidant enzyme activity.

Daily Mortality and Air Pollution in the Netherlands

ABSTRACT We studied the association of daily mortality with short-term variations in the ambient concentrations of major gaseous pollutants and PM in the Netherlands. The magnitude of the association in the four major urban areas was compared with that in the remainder of the country. Daily cause-specific mortality counts, air quality, temperature, relative humidity, and influenza data were obtained from 1986 to 1994. The relationship between daily mortality and air pollution was modeled using Poisson regression analysis. We adjusted for potential confounding due to long-term and seasonal trends, influenza epidemics, ambient temperature and relative humidity, day of the week, and holidays, using generalized additive models. Influenza episodes were associated with increased mortality up to 3 weeks later. Daily mortality was significantly associated with the concentration of all air pollutants. An increase in the PM10 concentration by 100 u.g/m3 was associated with a relative risk (RR) of 1.02 for total mortality. The largest RRs were found for pneumonia deaths. Ozone had the most consistent, independent association with mortality. Particulate air pollution (e.g., PM10, black smoke [BS]) was not more consistently associated with mortality than were the gaseous pollutants SO2 and NO2. Aerosol SO4 -2, NO3 -, and BS were more consistently associated with total mortality than was PM10. The RRs for all pollutants were substantially larger in the summer months than in the winter months. The RR of total mortality for PM10 was 1.10 for the summer and 1.03 for the winter. There was no consistent difference between RRs in the four major urban areas and the more rural areas.

Ambient air pollution and hospitalization for congestive heart failure among elderly people in seven large US cities.

Preexisting data sets were used to investigate the association between hospital admissions for congestive heart failure and air pollutants. Medicare hospital admissions data, ambient air pollution monitoring data, and meteorological data were used to create daily values of hospital admissions for congestive heart failure, maximum hourly temperature, and maximum hourly levels of carbon monoxide, nitrogen dioxide, sulfur dioxide, and ozone. Data were compiled for each of seven cities (Chicago, Detroit, Houston, Los Angeles, Milwaukee, New York, and Philadelphia) for 1986 through 1989. Single-pollutant and multipollutant models with adjustments for temperature, seasonal effects, and weekly cycles were used in conducting negative binomial regression analyses. Ambient carbon monoxide levels were positively associated with hospital admissions for congestive heart failure in the single-pollutant and multipollutant models for each of the seven cities. The relative risk of hospital admission for congestive heart failure associated with an increase of 10 ppm in carbon monoxide ranged from 1.10 in New York to 1.37 in Los Angeles. Hospital admissions for congestive heart failure exhibited a consistent association with daily variations in ambient carbon monoxide. This association was independent of season, temperature, and other major gaseous pollutants.

Effects of gaseous pollutants on forests in Eastern North America

The purpose of this paper is to summarize the current state of knowledge concerning direct forest damage caused by atmospheric gaseous pollutants. The major gaseous pollutants affecting forest growth are O3, SO2, and HF. Ozone is the most prevalent phytotoxic air pollutant on a regional scale in eastern North America. It has been demonstrated to cause foliar injury and growth effects on trees in both laboratory and field studies. Both SO2 and HF have been found to cause damage to forests primarily in the vicinity of strong point sources. Case histories of forest damage are reported in the paper which describe foliar and radial growth effects, with associated volume losses. Threshold levels of the gaseous pollutants causing effects on forest growth are provided.

A system for the long‐term continuous exposure of laboratory animals to mixtures of air pollutants1

Abstract A facility has been developed for the continuous chronic exposure of large numbers of animals to various levels of air pollution mixtures. It consists of four large environmental rooms which are self‐contained, each constituting a large exposure chamber. The rooms are suitable for housing almost any species of laboratory animals. A main air handler conditions and cleans outside air which is distributed to the four rooms and hallway. Air flow, temperature and humidity are precisely controlled independently in each room. Actual air pollution involves large numbers of trace substances and is impractical to reproduce entirely. For the present, a controlled mixture is being used, consisting of submicron sulfate aerosol and major gaseous pollutants in proportions similar to those in urban atmospheres. The mixture is introduced into three of the four exposure rooms at three pre‐determined levels; low (typical of average air pollution), high (alert or episodic levels) and exaggerated (or emergency levels...

A Novel Gas Analyzer for SO2, NO and NO2 in the Stack Effluent

A novel gas analyzer by UV absorption has been developed in order to measure the concentrations of sulphur dioxide, nitric oxide and nitrogen dioxide which are the major gaseous pollutants in the fossil fuel burner exhaust. Theoretical consideration of multiple ingredient measurement by light absorption, results of measurement of absorption cross sections of the three gases, discussion on the anomalous behavior of NO absorption and operating performance of the developed gas analyzer are described. The operating characteristics revealed this gas analyzer is useful for the monitoring of SO2, NO, and NO2 in the stack effluent.

Instrumentation for air pollution monitoring

Present air quality and emission standards are reviewed briefly. A description is given of the techniques that form the basis of current commercial instrumentation for measuring the five major gaseous atmospheric pollutants, SO/sub 2/, oxides of nitrogen, oxidants, carbon monoxide, and hydrocarbons. The uses of various types of ambient air monitors, stationary source monitors, and vehicular emission monitors are tabulated. (JGB)