Evaluating sources of indoor air pollution

Evaluation of indoor air pollution problems requires an understanding of the relationship between sources, air movement, and outdoor air exchange. Research is underway to investigate these relationships. A three-phase program is being implemented: 1) Environmental chambers are used to provide source emission factors for specific indoor pollutants; 2) An IAQ (Indoor Air Quality) model has been developed to calculate indoor pollutant concentrations based on chamber emissions data and the air exchange and air movement within the indoor environment; and 3) An IAQ test house is used to conduct experiments to evaluate the model results. Examples are provided to show how this coordinated approach can be used to evaluate specific sources of indoor air pollution. Two sources are examined: 1) para-dichlorobenzene emissions from solid moth repellant; and 2) particle emissions from unvented kerosene heaters. The evaluation process for both sources followed the three-phase approach discussed above. Para-dichlorobenzene emission factors were determined by small chamber testing at EPA's Air and Energy Engineering Research Laboratory. Particle emission factors for the kerosene heaters were developed in large chambers at the J. B. Pierce Foundation Laboratory. Both sources were subsequently evaluated in EPA's IAQ test house. The IAQ model predictions showed good agreement with the test house measurements when appropriate values were provided for source emissions, outside air exchange, in-house air movement, and deposition on "sink" surfaces.     

Public perception of air pollution sources across Europe

Air pollution is one of the primary concerns of our society for its effect on human health and the environment. Among the policy measures that can be put in place to limit air pollutant emissions, end-of-pipe technologies and/or regulatory instruments may be implemented through legislative acts. Also, equally important are behavioural measures, requiring citizens’ active involvement. The success of any measure to limit pollutant emissions requires the acceptance by the citizens that, in turn, implies a correct perception of the main pollutant emission drivers. We present here the comparison between the public perception of air pollution sources and the real-world situation through a survey carried out in seven European countries and involving 16 101 respondents. Our study shows a dramatic underestimation of the contribution of the agri-food sector to air pollution. This result is common to all respondents in the seven countries examined and only to a small extent depends on gender, age and socio-economic status of the respondents.     

Pattern recognition methods in air pollution control

Pattern recognition methods are used to predict future developments in terms of historical data by comparing graphs of atmospheric pollution concentrations. The method is then applied to a practical example of crisis prediction for CO concentration.     

生物过滤技术在大气污染控制中的应用

生物过滤技术是一项新兴的废气污染治理技术 ,正在逐步得到应用。本文主要介绍了生物过滤技术处理废气的使用范围、操作的基本原理及目前的应用情况 ,并且预测今后的发展方向。     

Catalytic oxidation for air pollution control

Bench-scale experiments have been conducted to evaluate a series of titania-supported Pt-Pd (as oxides) catalysts in the presence and absence of MoO₃ and Fe₂O₃ additives for their effectiveness in the complete catalytic oxidation of volatile organic compounds (VOCs) in air likely to be found in waste gases. Under oxidizing conditions, all of the catalysts promoted the complete oxidation of VOCs to CO₂ and H₂O. 99 % Conversion was achieved with a C₂H₄-C₂H₆ gas mixture in air at temperatures between about 160–450 °C and at a space velocity of 20,000 h^?1. Oxidation activity for the titania supported catalysts were found to decrease in the order Pt-Pd-Mo-Fe > Pt-Pd-Mo > Pt-Pd-Fe > Pt-Pd. However, the addition of MoO₃ and Fe₂O₃ increase the catalyst activity and reduce the reaction temperature for the complete destruction. Ageing was also performed in order to study the stability of the most active catalyst. Pt-Pd-Mo-Fe (as oxides) on titania catalyst is effective in oxidizing a wide range of volatile organic compounds at relatively low temperatures (220–405 °C) and and at a space velocity of 40,000 h^?1 and is resistant to poisoning by halogenated and amine volatile organic compounds.     

Chemical element balances and identification of air pollution sources in Washington,D.C.

Air filter samples were collected at four sites in Washington, D.C. during the summer of 1974 and analyzed for 27 elements. The average concentrations were interpreted by a chemical-element-balance method. The observed concentration pattern was resolved into six components: coal, oil and refuse combustion, marine aerosols, soil and motor vehicle emissions. Eight elements were used in the least-squares fitting of components. Concentrations of the non-volatile elements among the remaining 19 elements were predicted, on the average, to within a factor of two, with most elements agreeing within a factor of three. The major exceptions are Cr and Sb, for which the observed/predicted ratios were approx 4. Major sources of the elements indicated by the resolution are: coal, I, As, Se; soil, K, Mg, Mn; coal and soil, Al, Ca, Sc, Ti, Cr, Fe, La, Ce, Th; refuse, Zn, Cd, Sb; marine aerosols, Na; oil, V, Ni; motor vehicles, Pb, Br; mixed sources, Cu, Co, Cl, Ba. Despite considerable improvement of this resolution over previous attempts, several limitations of the method are noted and further refinements suggested.     

等离子体技术应用于气相污染物治理综述

近年来利用等离子体技术对气态污染物的氧化分解研究受到了广泛的关注.介绍了等离子体概念、分类及产生方法,简述了非平衡等离子体技术对气体污染物的降解原理,较全面地介绍了等离子体技术在脱硫、脱硝以及降解挥发性有机物(VOCs)等方面的研究.最后指出了今后等离子体处理废气的应用研究方向.     

A systems approach to air pollution control

A preliminary study for the systematic investigation and the control of the pollution of the atmosphere over a wide region is considered and discussed.