Ultrafine Particles: introduction

Particulate matter has long been noted as an atmospheric pollutant. As early as Roman times, residents of what had become the largest city in the world were well aware of the problem of “pestilential vapors and soot" now referred to as air pollution (Kahl, 1997). The emission sources for many of these pollutants were leather tanning facilities (Tanneries), smelting operations and home and municipal heating (Hughes, 1994).

Generally, the pollutant of concern with respect to particulate matter has been the larger diameter particles. At the turn of the century until approximately the early 1950’s, particulate matter related air quality issues were generally considered to be a function of the inefficient coal burning activities of industry and home heating (Stradling, 2003). Most of the effort during this period was focused on control technology (in the form of fuel modification) with some development in terms of particulate measurement (Stradling, 2003).

In the 1950’s and early 1960’s, particulate matter became a direct human health issue with the advent of radioactive fallout from above ground nuclear tests in the United States and abroad (Lalit, 1974). . The particulate matter in the air helped to foster a better understanding of the impacts that particulate matter has on human health and the environment.

The 1960’s and 1970’s saw rapid development of technology and policy leading to eventual improvements in United States air quality. As the science and technology of air quality measurement and human health impacts evolved, the characteristics of particulate matter and their impacts on human health became a greater issue for scientists and policy makers. The improvements include the ability to measure concentrations and particles at more refined levels of detection and the ability to assess human health in terms of environmental stressors.

Our ability to measure particles less than one micron (1µm) has also revealed a new potential human health concern related to particles and air quality. This fraction of particulate mater in the ambient air are characterized as ultrafine particles and are considered to be a significant human health concern because of the variable composition and the ability of these particles to penetrate deeply into the respiratory tract. Ultrafine particle research is an emerging topic and is a relatively new field of investigation. Ultrafine particles (UFP) were overlooked by the majority of investigators as a significant factor in respiratory tract health and health of other organs until 1994 when Oberdorster and Utell, (2002), introduced the hypothesis that UFP could cause toxicity to the human respiratory tract.

This discussion is focused on the various issues related to human health exposure and ultrafine particles. The discussion includes sections on the following:

Characteristics of Ultrafine Particles
Transport and Fate in the Environment
Measuring Exposure
Exposure Pathways
Risk Assessment
Prevention or Control of Exposures
Human Health Effects of Ultrafine Particles
Works Cited

This information is provided as a survey of the topic and is not intended as an authoritative source on the issue. The reader is directed to the literature cited in this document for further information on this topic.