Sacramento Bee article on NYC air hazards, Oct 2001

NYC 9/11 Public Portal Document

UC Davis News & Information :: Printable news Page 2 of 4

Just as the composition of inhaled particles can affect health, so can size.

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

Coarse partides are typically filtered by the nose or coughed out of the throat and upper lungs. They can irritate the mucous membranes, causing coughs and nosebleeds. In some individuals, they can cause allergic reactions sudt as dry eyes; nose, throat and skin irritation; coughing, sneezing and respiratory distress. They can also cause breathing problems or aggravate pre-existing breathing problems, such as asthma.

However, very fine partides can travel deep into human lungs. Such small partides may have no immediate apparent health effects in moderate concentrations, but they typically are removed from the lungs through the bloodstream and 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 "PM2.5" standard, which limits the allowable mass of airborne particles In the size range 2.5 micrometers to 0 micrometers. That standard is based on health studies of typical air samples. In which very fine particles are a small fraction of the total mass.

In contrast. In the World Trade Center samples analyzed at UC Davis, the very fine partides are a large fraction of the total mass.

In a nows conference today, the DELTA researchers described key findings in these categories: very fine particles, coarse particles, metals, asbestos and glass.

Very fine particles

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

In the largest spike, the DELTA Group analysis found 58 micrograms per cubic meter of very fine particles in one 45-minute period - "an extremely high peak," Cahill said.

Cahill said the very fine partides contained high levels of sulfur and sulfur-based compounds, which in early analyses appear to have been dominated by sulfuric add. The very fine partides also contain high levels of very fine silicon, 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 some other parts of Lower Manhattan, since weather data show that typically only part of the dust douds traveled directly over the sampling site.

"Even on the worst air days in Beijing, downwind from coal-fired power plants, or In the Kuwaiti oil fires, we did not see these levels of very fine particulates," Cahill said. The amounts of very fine partides, particularly very fine silicon, decreased sharply during the month of October.

Coarse particles

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

"These particles simply should not be there," Cahill said. "It had rained, sometimes heavily, on six days in the prior three weeks. That rain should have settled these coarse partides." The finding suggests that coarse partides were being continually generated from the hot debris pile. This observation is at least qualitatively supported, for while they are still being analyzed, the coarse partides appear to be coated with combustion products, induding soot, Cahill said.

Metals

Many different metals were found in the samples of very fine particles, and some were found at the highest levels ever recorded in air in the United States.

http://www-pubcomm.ucdavis.edu/default.Iasso?-database=news_db.fmp_&-layc... 2/11/2002

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