These studies related PM 10 concentrations to observed health effects. Adverse health effects from acute exposures to PM 10 may be confounded by the presence of other pollutants making it difficult to estimate that portion of risk attributable solely to PM 10 . However, analytical results of air quality samples taken in the KTO in 1991 do not indicate that other air contaminants were at levels of concern. Nevertheless, uncertainties persist with this type of analysis suggesting that this issue is a candidate for further research. Chronic Effects Associated with Particulate Matter Exposure Chronic pulmonary function studies are less numerous than acute studies and the results are inconclusive and in some cases inconsistent in findings.
Some studies show effects for some endpoints, but other studies fail to find for the same effects.
None of the recent studies have focused on a study population similar in age, health, and physical ability to that of Gulf War veterans. Therefore some other means of estimating the chronic effects of exposure is necessary and will be discussed in the next section. B. Particulate Matter Components of Concern Since airborne particulate matter is not a single pollutant, but rather a varying mixture of pollutants each with its own subclass of different chemical species, it is difficult to estimate the total risk of adverse health effects from exposure to particulate matter based solely on the analysis of its individual component species. That is, the risks are not necessarily additive. With these factors in mind, silica and soot have been identified as potential contaminants of concern as found in the particulate matter concentrations measured in air samples taken in the KTO in 1991.