2010 March 16: NY: PM2.5 interpreted
beyond OC – A Method to Extract & Interpret Additional Aerosol Organic Carbon Fractions from Thermal Optical Analysis of Filter-based and Continuous Data
Carbonaceous aerosols, a subset of particulate matter, are small solid or liquid particles suspended in the air, consisting predominantly of organic substances such as carbon, hydrogen, and oxygen ("organic carbon," or OC), and various forms of elemental carbon (EC), sometimes referred to as black carbon (BC) or soot. Carbonaceous aerosols have been linked to significant human health impacts, including increased respiratory symptoms, decreased lung function, aggravated asthma, chronic bronchitis, irregular heartbeat, nonfatal heart attacks, and premature death in people with heart or lung disease. They also impact global warming in numerous ways, and are intensely studied for their importance to this critical issue.
Particulate matter is categorized by size. Many human health impacts are ascribed to fine particles, referred to as PM
2.5 (those particles with a diameter of 2.5 μm or smaller). In the Eastern U.S., carbonaceous aerosols generally comprise the largest or second largest portion of fine particles, with sulfates the other major portion. To protect human health, the U.S. Environmental Protection Agency (U.S. EPA) established National Ambient Air Quality Standards (NAAQS) for PM2.5 and PM10 (particles with a diameter of 10 μm or smaller). Portions of southern New York are designated as nonattainment areas for failing to meet these standards.
Carbonaceous aerosols are produced by a variety of natural processes and human activities, including fossil-fuel combustion, forest fires, agricultural practices, and industrial manufacturing. They can also result from atmospheric transformations of hydrocarbons from gaseous to condensed forms, known as secondary organic aerosol production. The complexity of this air chemistry presents a major challenge to measurement, modeling, and policymaking.
Although data on carbonaceous aerosols are collected by air sampling stations (the Speciation Trends Network, or STN) located throughout the State, analysis of the collected samples only divides the aerosol carbon into empirical fractions, rather than producing truly speciated data. More thorough analysis of these existing data could reveal much about the composition and source of carbonaceous aerosols in New York State’s air, as well as the associated atmospheric processes.
Source: E&S Environmental Chemistry, Inc.
Carbonaceous aerosols make up a large fraction of PM
2.5 in most areas of the country. These fine particles negatively impact human health, cause environmental damage and contribute to global warming. Currently, portions of New York State are designated nonattainment areas for failing to meet U.S. EPA air quality standards for airborne particles. In order to reduce carbonaceous aerosol levels in nonattainment areas of New York State, policymakers must better understand the sources and evolution of these aerosols. This project will aid in understanding the types and volatility of compounds that make up carbonaceous aerosols, and will result in improved techniques to aid in their categorization. The results will benefit efforts to improve air quality and address climate change in New York State. Specifically, this study may help policymakers cost-effectively target the specific sources of PM2.5 in New York State’s air.
To date, the project team has characterized the response of 17 carbon compounds using four different temperature programs, and has developed a new temperature program that improves results for some of the tested compounds, especially for the PAH compounds fluoranthene and benzo[a]pyrene. The project team has also identified periods of interest from New York City data.
With the combination of additional laboratory measurements and additional analysis and interpretation, the project team expects to better characterize measured ambient aerosols, and shed light on their sources.