During dust storms, increase

The people who are most at risk for health problems from particulate exposure are those who already have some form of respiratory disorder or heart disease, the elderly, and children. Such problems begin to appear when the ambient concentration of pollutants reaches about 40 pg/m for PM25 particulates and about 150 pg/m for PM particulates. Such concentrations are observed during dust storms, along dusty unpaved roads, and in areas with high levels of motor vehicle traffic, for instance. Increasing concentrations of both PM2 5 and PMj particulates result in more serious health problems, including asthma, bronchitis, emphysema, and cardiac problems. 

Although most of the oil from the lakes has been removed or has been the subject of heavy weathering, the lakebeds still contain a large amount of oil, which cannot be easily removed. Analysis of samples indicated that the composition of the oil in the lakes continues to change [77]. The chemical composition of weathered oil showed a decrease in aromatic compounds, and an increase in resins and higher polycyclic aromatic hydrocarbons. This inaeases the hazard potential of oil lakes. Heavily contaminated soils may eventually erode and be resuspended and transported to populated areas during dust storms and could cause health hazards [35]. There is also the possibility of contaminating soil with heavy metals, particularly nickel, vanadium, chromium, and lead. 

As an indication of the effect of dust storm episodes on the aerosol concentration in the valley, the per cent Increase in the weekly total mass, coarse sulfur, chlorine, silicon, and iron concentration during a dust storm was computed. In addition, the absolute Increase in these quantities was also computed. The results of this analysis are shown in Table II. These data also indicate that a significant increase in aerosol concentration due to suspended lake bed materials occurs as far downwind as Independence. In order to quantify this effect, the sulfur to iron (S/Fe) and chlorine to iron (Cl/Fe) ratio at each site was examined. At Keeler, all the coarse sulfur and iron measured at the sampling site are suspended from the lake bed. At any site... 

Since the amount of dust suspended in the Martian atmosphere varies a great deal by season, by altitude, and by latitude, the SCIM Mission would be planned so that it would arrive during the period of greatest atmospheric dust content and at the best altitude and latitude for maximum dust collection. The presence of a significant dust storm on Mars cannot be accurately predicted however, a dust storm would only increase the atmospheric dust content and thus the amount of sample collected and returned. 

When dust storms develop in the deserts of Middle Asia and break into the mountain country of Pamiro-Alai the dust load in the convective layer of the troposphere increases. Meteorological stations record dust haze during these episodes (Fig. 1). 

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