Air quality particulate matter guidance, NYC, Oct 2001

NYC 9/11 Public Portal Document

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PARTICULATE MATTER AIR QUALITY: PARTICULATE MATTER

NOTE: This document was designed to assist public health officials in communicating specific air quality issues to the general public. Additional materials (e.g., fact sheets) will be supplied for public distribution.

Air Quality:

The Environmental Assessment Workgroup, comprised of members from the Agency for Toxic Substances and Disease Registry (ATSDR), Centers for Disease Control and Prevention (CDC), Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA), is recommending that people in New York City make an effort to reduce their exposure to air contaminants due to the fires, smoke, and dust (also known as particulate matter) created by the collapse of WTC and on-going response in Lower Manhattan. It is especially important for people with heart or respiratory disease, the elderly and young children to reduce their exposure to smoke and dust since they are likely to be more sensitive to the effects of particulate matter.

Health complaints from the area have been primarily irritant and respiratory in nature (such as coughing, irritation of the eyes, nose and throat, wheezing, difficulty in breathing and shortness of breath). Airborne particulate matter known to cause these types of acute health effects include smoke, fiberglass, and inhalable dust (e.g., cement and gypsum). Certain compounds in airborne particles may be present that may result in chronic health problems, including respirable silica and asbestos. Efforts to measure air quality are focusing on all these types of airborne particles.

Particulate Matter:

The term “particulate matter” (PM) includes both solid particles and liquid droplets found in air. Many human activities and natural events emit PM directly or emit other pollutants that react in the air to form PM. These solid and liquid particles come in a wide range of size. Particles less than 10 micrometers in aerodynamic diameter tend to pose the greatest health concern because they can pass through the nose and throat and be deposited in the lungs. Particles less than 2.5 micrometers in diameter are referred to as “fine” particles. Sources of fine particles include all types of combustion (motor vehicles, power plants, fires, etc.) and some industrial processes. Particles with diameters between 2.5 and 10 micrometers are referred to as “coarse” particles. Sources of coarse particles include crushing and grinding operations, and dust from paved and. unpaved roads. The particle mix in most U.S. cities is dominated by fine particles generated by combustion with smaller amounts of coarse dust. The coarse dust resulting from the collapse of World Trade Center (WTC) buildings and the removal of rubble contains-particles from building materials.

In order to address public health issues associated with PM in air, some characterization of airborne particulate niatter is warranted to provide additional information. The likelihood for particles to produce certain health effects is also related to particle size. Larger particles are less likely to penetrate deeply into the lungs and can be deposited on mucous membranes of the eyes, nose and throat as part of the body’s natural defense system. Particles deposited on these surfaces can cause irritation. As particle size decreases the likelihood for them to reach more deeply into the lungs increases. Particles depositing in the lower regions of the lungs can produce both short term effects, such as coughing and longer term effects such as changes in lung function. Specific characteristics (e.g. chemical composition) of these particles can also influence the types of health effects seen following exposure.

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