Background

One of the most basic forms of air pollution - haze - degrades visibility in many American cities and scenic areas. Haze is caused when sunlight encounters tiny pollution particles in the air, which reduce the clarity and color of what we see, and particularly during humid conditions. Since 1988 the federal government has been monitoring visibility in national parks and wilderness areas.

PM2.5 concentrations measured at the urban site in the NCR (Haines Point) are well correlated with those at more rural sites (i.e., Dolly Sods) to the west. This indicates that the Haines Point measurements can be taken to represent regional PM2.5 trends in a relative sense, although Dolly Sods measurements were 25 to 200% lower for any given measurement on an absolute basis. In addition, a web-enabled camera was established at the Netherland Carillion (GWMP) in 2003 to track visibility of the Washington Monument. This "optical monitoring" can help validate the nephelometer and PM2.5 measurements, identify the sensitivity of the NCR viewshed to particulate pollution, and provide a basis from which to model future visibility impairment or improvements for the region. Trends in PM2.5 can be tracked using the IMPROVE website for access to the Haines Point measurements.

Objectives

• Assess seasonal and annual status and trends of fine particle concentrations in the National Capital Region Network as they pertain to visibility impairment and human health.
• Track and interpret visual impairment with cameras.

Reports
2009 Annual Air Report
2008 Annual Air Report
2006 Annual Air Report
2005 Annual Air Report

Links
Monitoring Protocol
Visibility Data and Trends
Washington, DC Web Cam

Contacts
Patrick Campbell
NCRN Network Coordinator
202.342.1443 ext. 229
202.342.1443 ext. 214

Measures

Particle monitoring is conducted by the Maryland Department of Natural Resources, District of Columbia, Virginia Department of Environmental Quality and NPS. The NPS monitoring is part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) program, a national program focused on monitoring visibility in national parks and wilderness areas. In addition to particle data, optical data are collected at a number of IMPROVE sites. Optical monitoring helps validate the particle data, and through the use of digital photos and web-enabled cameras, provides a means of providing and interpreting visibility data to the public. IMPROVE posts site-specific and programwide data on the VIEWS website. NPS ARD will provide fine particle trend data annually for parks with IMPROVE monitoring. As appropriate, NCRN will supplement information obtained from ARD with data summaries, interpretations and graphics available on the VIEWS website. Monitoring specialists at the NPS ARD are developing guidance on downloading information from the VIEWS site in ways that will be most useful to report on status and trends in visibility in Network parks.

Status

The NPS Air Resources Division has been collecting visibility data in the National Capital Region for nearly 20 years. PM2.5 concentrations are measured at the urban site in the NCR (Haines Point) and a web-enabled camera was established at the Netherland Carillion (GWMP) in 2003 to track visibility of the Washington Monument. The NCRN has been working with ARD and the regional air resources specialist to interpret, summarize and report the data collected.