II.  BACKGROUND

Particulate matter (PM) is a generic term applied to a broad class of chemically, physically, and biologically diverse substances spanning a range of particle sizes. Typically, airborne PM ranges in size frommolecular clusters of less than 0.001 micron (mm) to particles more than 50 mm in diameter. A 10 mm particle is roughly one-sixth the width of a human hair. These particles are transported in the air as solid particles or liquid droplets.[5]

Particle size analyses conducted on air samples taken in 1991 at several locations in Kuwait and Saudi Arabia (Section III) indicated that there was a significant mass of particles in the respirable size range (i.e., less than 10 mm in aerodynamic equivalent diameter). Particles in this size range (commonly referred to as PM10) have the potential for entering the thoracic region of the respiratory tract and will deposit either in the tracheobronchial region (conducting airways of the lung) or in the pulmonary region (alveolar region where gas exchange occurs). How far a particle penetrates the pulmonary region is a function of the particle aerodynamic equivalent diameter and collection efficiency of the respiratory tract for a given particle aerodynamic equivalent diameter. When found at high concentrations in the ambient environment and under conditions of extended exposure, these particles have been associated with changes in lung function, damage to lung tissue, and altered respiratory defense mechanisms (impaired ability to naturally eject foreign matter via exhalation). In an occupational setting, PM10 exposures with higher concentrations and/or longer durations have resulted in similar, if not more severe, health effects. Dose and duration of exposure are equally important factors when assessing health effects.

Shortly after the Gulf War, the US Army Environmental Hygiene Agency (USAEHA) initiated a comprehensive air quality monitoring program that tracked PM levels. Analysts conducting sample analyses have determined that roughly 75 percent of the PM originated from sand common to this part of the world, 23 percent from oil fires, and 2 percent frommiscellaneous sources such as gasoline engine emissions, crude oil refining operations, and natural transformation of gaseous emissions in the atmosphere (e.g., sulfur oxides, nitrogen oxides, and volatile organic substances).[6]

While still in Iraq following the cease-fire, a severe sandstorm occurred that lasted all day. The sand and dust was so dense that [we] could not see objects even 30 meters distant…our guns were deployed 35 meters apart, and we could not see the guns on either side of our position

- Gulf War veteran[7]

Sand and dust storms are problematic year round in Kuwait and Saudi Arabia, but are worse during the summer when the northwesterly shamal winds occur with greater frequency and intensity.[8]Because sand and dust can irritate the skin and sensitive membranes of the eyes, nose, and throat, and aggravate sinus and asthmatic conditions, it was necessary for US personnel in the Gulf to protect themselves against wind blown sand. Consequently, standard personal protective items available to most US personnel included goggles and large kerchief-type cloths or similar protection for the airways. Various directives and policy statements directed or advised the use of these items.[9]

Many US personnel trained, operated, and lived in the desert, causing military health personnel concern about the possible adverse health effects of exposure to high levels of blowing and suspended sand. The grain size of the sand was characteristically small, and some personnel with pre-existing respiratory problems experienced aggravated symptoms.

In addition to respiratory symptoms attributed to the high PM levels, some military personnel also developed viral infections as a result of community living conditions. A study conducted on 2,598 personnel stationed in northern Saudi Arabia found that the type of structure in which an individual slept might have been as important a determinant for developing respiratory complaints as exposure to outdoor air pollutants. Personnel who slept in air-conditioned buildings were much more likely to develop a cough and sore throat than those billeted in tents and warehouses. The study suggests that it was unlikely that all respiratory complaints experienced during the Gulf War were solely the result of exposure to high PM levels.[10] Personnel living in tightly constructed buildings were more likely to pass respiratory infections among each other, and the respiratory infections observed in the Kuwait theater of operations (KTO) during the Gulf War were caused by well-known, common viral and bacterial agents.[11] Similar findings have been observed in US military training bases where recruits living in modern, energy-efficient barracks with closed ventilation systems were found to be at higher risk from respiratory-transmitted infections.

The rates of outpatient treatment were slightly higher early in the Gulf War deployment, when personnel tended to be crowded together in transport aircraft, ships, ports of debarkation, and rally or assembly areas. Respiratory disease rates showed a rapid decline as forces dispersed into field positions, but rose again when the weather turned cold. These acute respiratory illness patterns are similar to what is typically seen at military installations in the US.[12]

The health issues surrounding the short- and long-term exposures to PM10 are discussed in Section V of this report.

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