Volatile organic compounds (VOCs) emitted from surface coatings have caused growing public concern for air quality. Even the low-emitted VOC impact from water-based paints on indoor air quality in urban areas has caused concern. This paper presents experimental data using a mathematical model to simulate dynamic VOC emissions from water-based paints that is based on mass transfer and molecular diffusion theories. A series of field-analogous experiments were carried out to continuously measure the VOCs emitted from two typical water-based paints using a gas chromatography-flame-ionization detector monitor in an artificial wind tunnel system. In the study cases, the mass flux of VOCs emitted from the water-based paints was up to 50 g/m 2 sec. It was found that the time needed to completely emit VOCs from water-based paints is just hundreds of seconds. However, the order of magnitude of the VOC emission rate from water-based paints is not lower than that from some dry building materials and solvent-based paints. The experimental data were used to produce a useful semiempirical correlation to estimate the VOC emission rates for water-based paints. This correlation is valid under appropriate conditions as suggested by this work with a statistical deviation of Ϯ7.6%. With this correlation, it seems feasible to predict the dynamic emission rates for VOCs during a painting process. This correlation is applicable for assessing the hazardous air pollutant impact on indoor air quality or for environmental risk assessment. Associated with the dynamic VOC emission characterization, the air-exchange rate effect on the VOC emission rates is also discussed.

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From an engineering application point of view in reducing fugitive particulate matter emissions, this paper presents experimental data comparing the efficiency of woven straw at reducing entrained emissions of particulate matter with diameters less than 10 mm (PM10) with that for particulate matter with diameters less than 2.5 mm (PM2.5) at construction sites. A series of field-analogous experiments were carried out to continuously measure PM10 and PM2.5 using laser particle monitors in an artificial wind tunnel system. It was found that the efficiency of woven straw at reducing either PM10 or PM2.5 is significantly dependent on the woven straw coverage ratio. The maximum reduction efficiencies for PM10 and PM2.5 are about 40% and 12%, respectively. Note that the reduction efficiencies approach zero as the coverage ratio is less than about 40%. Total elimination of PM2.5 and PM10 emissions is not possible, even using full-coverage woven straw. Reduction of PM2.5 emissions is less efficient than that of PM10 emissions using woven straw, and this trend is likely more obvious with an increase in the woven straw coverage ratio. The ratio of reduction efficiencies (R) between PM 2.5 and PM 10 for woven straw decreased slightly with an increase in the woven straw coverage ratio. Overall, for wind speeds of 0.5-3.0 m/s, silt contents of 4.8%-21.0%, and soil moisture contents of 10%-30% as used in this work, the average value of R is 0.31. The effects of wind velocity, silt content, and moisture content on the reduction efficiencies are also discussed.Résumé : D'un point de vue d'application technique pour réduire les émissions fugitives de matières particulaires, cet article présente des données expérimentales pour comparer l'efficacité en réduction de la paille tissée pour les émissions de matières particulaires entre PM 10 et PM 2,5 de zones exposées. Dans cette étude, des d'expériences analogues sur le terrain ont été réalisées pour mesurer en continu les PM 10 et PM 2,5 au moyen de détecteurs de particules au laser dans un tunnel aérodynamique artificiel. L'efficacité de la réduction de la paille tressée à réduire soit PM 10 ou PM 2,5 dépend beaucoup du rapport de couverture de la paille tressée. Les efficacités maximales de réduction pour PM 10 et PM 2,5 sont respectivement d'environ 40 % et 12 %. Il faut remarquer que les efficacités de réduction atteignent près de zéro lorsque le rapport de couverture est inférieur à environ 40 %. Un autre point intéressant est que l'élimination totale des émissions PM 2,5 et PM 10 est impossible même en utilisant une couverture complète de paille tressée. La réduction des émissions PM 2,5 est moins efficace que celle des émissions PM 10 pour la paille tressée et cette tendance sera probablement plus évidente avec l'augmentation du rapport de couverture en paille tressée. La présente étude montre que le rapport des efficacités de réduc-tion (R) entre PM 2,5 et PM 10 par la paille tressée diminue un peu avec une augmentation du rapport de couverture de paille tressée. Règle généra...