Atmospheric Aerosols

What are atmospheric aerosols?

Aerosols describe the ubiquitous presence of condensed species (liquid or solid) suspended in air. While they are always present, the concentration of aerosols ranges from very low on crisp clear days with dark blue skies and good visibility, to very high on extremely polluted days when even the sun is obscured by high aerosol concentration. Another term for atmospheric aerosols is "Particulate Matter" or PM. The units used to measure PM are micrograms of condensed species (or particles) per cubic meter of ambient air. The United States EPA or Environmental Protection Agency (and similar agencies in most other countries) has determined that high levels of PM are harmful to human health, causing heart and lung problems in susceptible populations. EPA has established a mass‐based National Ambient Air Quality Standard for PM to protect human health.

History of atmospheric aerosols at Whiteface Mountain

Aerosol research was a major focus of ASRC activity in the 1960's and 1970's, and there were measurements at Whiteface Mountain as well as locations around the world. Some work included the measurement of condensation nuclei, or Aitken nuclei at Whiteface Mountain summit and/or lodge locations. Under the guidance of Ray Falconer, ASRC for a time carried out a project that involved daily monitoring of the condensation nuclei number concentrations at some fourteen locations across New York State, including Whiteface. Collection of filter samples of particulate matter at Whiteface started in 1975 by researchers at NYSDOH (New York State Department of Health). This sampling program of Total Suspended particles (TSP) continued until 2020 and produced an invaluable archive of the history of this airshed.

In 1997 the EPA established an air quality standard for PM2.5, defined as those particles with aerodynamic diameter less than 2.5 micrometers that are captured and measured gravimetrically. Shortly after the establishment of this new standard, NYSDEC (New York State Department of Environmental Conservation) installed a Federal Reference Method (FRM) filter sampler at the Marble Mountain lodge site. This is the "cleanest" site in their measurement network, and provides a baseline reference for clean background mass concentrations of PM2.5. The measurements continue to the present, currently on a 1 in 6 day schedule. The lodge site also hosts filter sampling for chemical speciation, on the same 1 in 6 day sampling schedule as the FRM filters. In addition to the integrated filter samples, continuous PM2.5 mass concentration is measured with an oscillating microbalance monitor, and semi‐continuous PM2.5 sulfate is measured using a sulfate aerosol analyzer.

Whiteface Mountain was one of the sites chosen by ASRC for its project award under Phase Two of the EPA PM Supersites program. The ASRC program was called "Particulate Matter Technology Assessment and Characterization Study‐New York" (PMTACS‐NY). The study included a month long intensive at the lodge location with upwards of 20 new measurement systems for PM and gaseous species. This study produced much knowledge about atmospheric aerosols in a remote mountainous location and the measurement methods required to fully characterize them.

Why is it important to study atmospheric aerosols?

As noted on the main Scientific Research page, aerosols impact nearly all areas of atmospheric science. They have been proven to have a negative effect on human health, so studying aerosols and determining how to lower their concentration and corresponding health impact is a major motivating factor in this activity. Their direct and indirect impact on climate through their role in reflecting and absorbing incoming solar radiation is another critical area of study. Aerosols also act as seed particles for cloud droplet and eventually rain droplet growth. This interaction with meteorological processes such as precipitation and cloud formation and lifetime is one more reason to understand all we can about the physics and chemistry of atmospheric aerosols.