Open-Path FTIR (Fourier-Transform Infrared) is a
sophisticated instrument package that allows real-time,
continuous measurement of a broad range of volatile
organic and inorganic compounds.
OP-FTIRs are based on infrared spectrometers used
in chemical labs since the 1960s. However, FTIR
technology as a field application to measure airborne
chemical levels is relatively new since the early 1990s.
FTIR monitors provide both qualitative and quantitative
information; which means they identify the compounds
present and also calculate the concentration of each.
FTIR monitors received the official endorsement
of the Environmental Protection Agency in 1998 when it
published EPA Standard Method TO-16, in which EPA
recommends FTIR as the best technology for measuring
airborne pollutants in residential areas.
“Open-Path” designation means that the infrared
light source and detector are both contained in the same
allows the infrared beam to be directed over variable
distances and directions to a retro-reflector that
returns the beam to the monitor. The actual distance measured is therefore twice the distance
separating the FTIR monitor and the reflector.
This feature also allows the reflector to be
easily repositioned to measure volatile pollutants in
other directions and over varying distances.
FTIR monitors are suitable for field applications, such
as in residential areas near the Intel manufacturing
plant in Rio Rancho, New Mexico, where nearby community
members have had concerns about gaseous toxic chemical
releases from the Intel plant. FTIR monitors are
likewise suitable for monitoring toxic chemicals in the
vicinity of other Intel facilities, such as those
in Chandler, Arizona and
Beaverton, Oregon where volatile organic and/or
inorganic compounds are released.
monitors can measure nearly all volatile compounds,
except for diatomic molecules of the same element, such
as chlorine and fluorine.
Essentially all other volatile chemicals,
including organo-metallic compounds will be detectable
if they are gases. Other volatile acids such as
hydrogen chloride (HCl) and hydrogen fluoride (HF) will
be detectable if Intel is releasing them. A
significant portion of Intel's emissions are volatile
organic compounds (VOCs), of which Intel may be emitting
more compounds and higher volumes than those it reports
to the New Mexico Environment Department.
monitors measure only gaseous compounds, and thus cannot
measure particulate matter (soot, smoke, dust, etc.)
Nonetheless, the FTIR monitors serve as a potent tool
for identifying what gaseous organic and inorganic
chemicals Intel is releasing and what their concentrations are in the
detection limits for most of the organic chemicals
emitted from Intel are in the low parts-per-billion
range, which is excellent for a continuous, real-time
When nearby residents can smell Intel's
emissions, as they report, the concentrations
probably range from the high parts per billion levels to
low parts per million.
monitor will detect most of the chemicals being emitted
by Intel when the wind is blowing from the plant's
stacks/vents toward the FTIR monitoring path.
Because the FTIR monitor includes a weather station,
each measurement incorporates the wind speed and wind
direction at that time. This combination of weather data
and detected compounds makes it relatively easy to
identify the most probable source of the emissions.
One of the CRCAW members is
retrieving collected data from FTIR.
Front view of FTIR
Side view of FTIR
Front view of Retro-Reflector, which allows
it to return the reflected beam to its exact point of