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UC Davis News & Information Trade Center Air Held Unprecedented Amounts... Page 2 of 4

The team analyzed the particles by size in eight ranges from coarse (12 micrometers to 5 micrometers in dk fine (0.24 micrometers to 0.09 micrometers In diameter). Most of the ultrafine mode (partides less than 0.1 n was not cdlected.

Coarse particles are typically flltered the nose or coughed out of the throat and upper lungs. Thc^ cat Irrll mucous membranes, cau^ng coughs and nosebleeds. In some individuals, they can cause allet^c reaction! eyes; nose, throat and sWn Irritation; coughing, sneezing and respiratory distress. They cat also cause brea or aggravate pre-existing breathing problems, such as asthma.

However, very fine particles can travel deep Into human lungs. Such small particles may have no immediate health effects in moderate concentrations, but they typically are removed from the lungs through the bloodsti heart, increasing the possibility of health impacts.

There are no established safe limits for inhaled very fine particles. The closest reference is the U.S. EPA "Pf whtoh limits the allowable mass of airborne particles in the size range 2.5 micrometers to 0 micrometers. Th; based on health studies of typical air sample, in which very fine particles are a small fraction of the total ma

In contrast. In the World Trade Center samples analyzed at UC Davis, the very fine particles are a large frac mass.

In a news conference today, the DELTA researchers described key findings in these categories; very fine pa particles, metals, asbestos and glass.

Very fine particles

There were numerous events when bursts of wind lasting six to eight hours carried unprecedented amounts particles to the sampling site.

tn the largest sfMke. the DELTA Group analysis found 58 microgtams per cubic meter of very fine particles in period - "an extrarnely high peak," Cahill said.

Cahill said the very fine particles contained high levels of sulfur and sulfur-based compounds, which in early appear to have been dominated by sulfuric add. The very fine partides also contain high levels of very fine s potentially from the thousands of tons of glass in the debris.

Cahill noted that even those large amounts were likely to be smaller than those present at Ground Zero and parts of Lower Manhattan, since weather data show that typically only part of the dust clouds traveled directI sampling site.

"Even on the worst air days in Beijing, downwind from coal-fired power plants, or In the Kuwaiti oil fires, we t these levels of very fine particulates," Cahill said. The amounts of very fine particles, particularly very fine sill decreased sharply during the month of October.

Coarse particles

Sitnila to the high concentrations of very fine particles, virtually all the air samples from the trade center site concentrations of coarse particles - those about 12 micrometers to 5 micrometers in dlamefer.

"These particles simply should not be there," Cahill said. "It had rained, sometimes heavily, on six days in tb weeks. That rain should have settled these coarse particles." The flndirrg suggests that coarse particles wen continually generated from the hot debris pile. This observation Is at least qualitatively supported, for while ti being analyzed, the coarse particles appear to be coated with combustion products, including soot, Cahill sa

Metals

Many different metals were found In the samples of very fine particles, and some ware found at the highest h recorded In air in the Uifited States.

However, there are few established safety guidelines for airborne metals. One metal for which there is a guk was present at low levels in fine arto very fine particles.

Some of the metals for which there are no guidelines that were present In very fino particles In relatively higt concentrations were iron, titanium (some associated with powdered concrete), vanadium and nickel (often a:

http;//www-pubcomm.ucdavis.edu/defeult.lasso?-database=news_db.frnp_&-Iayc... 25/11/2002

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