Journal of the Air & Waste Management Association最新文献

The "irritation signaling" model proposed that a long term contribution to chronic bronchitis might result from the repeated delivery of "signals" resulting from temporary localized acidification of the bronchial epithelium by the action of individual particles. This led to a prediction that the effectiveness of particles in inducing changes in mucus secreting cell numbers/types should depend on the number of particles deposited that contained a particular amount of acid--implying that particles below a certain size cutoff (and therefore lacking a minimum amount of acid) should be ineffective; and that particle potency per unit weight should be greatest at the cutoff and decline strongly above the cutoff. Since the development of this hypothesis both epidemiological observations and some experimental studies have tended to reinforce the notion that acid particles can make a contribution to relatively long lasting bronchitic-like changes, and enhance the desirability of more direct testing of the model. In this paper we develop a general theoretical framework for the contributions of environmental agents to chronic obstructive lung disease, and a series of alternative hypotheses against which the predictions of the "irritant signaling" model can be compared. Based on this, we suggest a research program that could be used to further develop and test the model and reasonable alternatives.

Although fixed-site monitoring data have been used to estimate the spatial pattern of human exposure, the intra-urban distribution of actual exposure has not been documented. This paper used the data collected during the Environmental Protection Agency's (EPA) field investigation of personal exposure to carbon monoxide (CO) to investigate the nature of the distribution of CO with respect to residential location in the Washington, D.C. SMSA. Dot-distribution maps and analysis of variance were used to document the spatial pattern of individual-level in-home CO concentrations. The results show sampled individuals living in the SMSA center are exposed to statistically significantly higher levels of CO than are those living in the suburbs. The most important implications of this work are for exposure modeling. Further investigation is needed to determine whether incorporation of a geographic component will improve exposure prediction.

Forced-air heating and air conditioning (HAC) systems caused an average and maximum increase in air infiltration rates of 1.8- and 4.3-fold, respectively, during brief whole-house studies of tracer gas decay in 39 occupied houses. An average increase in air infiltration rate of 0.33 +/- 0.37 h-1 corresponded to an incremental air leak of 240 m3/h, based on approximate house volume. More detailed tracer gas decay studies were performed in basement, kitchen and bedroom locations of six homes with low air infiltration rates (i.e., less than 0.25 h-1). The HAC mixed the indoor air efficiently between measurement sites. HAC operation also caused 1.1- to 3.6-fold increases in air infiltration rates, corresponding to absolute increases of 0.02 to 0.1 h-1. In an unoccupied research house, three-fold increases in average air infiltration rate with HAC operation (i.e., from 0.13 to 0.36 h-1) were reduced to two-fold (i.e., from 0.10 to 0.18 h-1) by sealing the external HAC unit and crawlspace ductwork system. This sealing also resulted in a 30 percent reduction in crawlspace-to-indoor transport rates with the HAC turned on. Blower door tests indicated a less than 20 percent reduction in house leakage area.

The United States Department of Health and Human Services through Wayne State University (WSU) has completed a study of hazardous waste education and training in the United States. The study documents university course work and degrees as well as non-degree continuing education short courses. Major portions of the study are based on a WSU sponsored survey in which 1469 four-year degree granting institutions were contacted. Of the 732 institutions responding, 113 were identified as offering course work of some kind in hazardous waste. Information on 499 distinct non-degree short courses was also gathered and evaluated. The purpose, methodology and results of the study are summarized in this article.