Airborne Fine and Ultrafine Particles Near the World Trade Center Disaster Site

摘要

Documentation of the airborne fine and ultrafine particles produced by the terrorist attack on the World Trade Center (WTC),particularly while fires were burning,was essential for evaluating the risk of adverse health effects in people who live and work in this area.We collected airborne particles for 3 months at a site about 400 m east of the former WTC.Ultrafine particles were collected by deposition onto small detector chips for morphometric analysis by atomic force microscopy.Some chips were coated with an iron nanofilm for detection of strong acids.A condensation nucleus counter and two impactors measured particle number concentrations and size distributions.Collected particles exhibited a variety of globular forms,and most appeared to be agglomerates.No ultrafine acid particles were detected.Particle number concentrations ranged from below Ixl0~4 cm~(-3) to about 5xl0~4 cm~(-3).Occasional peaks reached values over 7 x 10~4 cm~(-3).The average total mass concentration was about 17 mug/m~3 in mid-October,about half that value in November,and as low as 5 mug/m~3 in mid-December.Particle size distributions were mostly bimodal.The mass concentration of very fine particles (0.1 mum to 0.29 mum) ranged from 4.3 mug/m~3 to 0.7 mug/m~3,and the ultrafine (d < 0.1 mum) ranged from 1.46 mug/m~3 to nondetectable after 5 November 2001.Some backup filters from the October sampling sessions were analyzed for organic and elemental carbon (OC/EC) and polyaro-matic hydrocarbons (PAH).About 70 of the total carbon was organic.The PAH levels ranged from 10 to 1500 ng m~3.Overall,our data for particle mass and number concentrations did not differ substantially from data we had collected in Manhattan the previous year.The dominant organic compounds found in these samples are those most common in urban environments.These data do not suggest,but cannot rule out,an unusual risk of adverse health effects from the number,or mass,of the fine ambient particles.