Identifying unknown airborne chemicals in industrial hygiene with real-time FTIR
Real-time FTIR lets an industrial hygienist identify and measure unknown gases directly in workplace air, so confirmatory sampling can focus on the compounds that are present. Industrial hygiene often starts with a simple question: What are employees being exposed to?
In many workplaces, the answer is not always obvious. Safety Data Sheets (SDSs) provide useful information about chemicals used in a process, but they do not necessarily describe every substance that could be present in the air. Formulations can contain multiple components, and processes such as heating, curing, coating, or other forms of manufacturing can release additional compounds into the workplace atmosphere
Why is it hard to sample for unknown gases in workplace air?
Traditional exposure assessment works well when potential hazards are already known. If a process is known to produce a particular solvent, metal, dust, or other substance, the appropriate sampling method can be selected in advance.
The situation is more difficult when the composition of a material or process is not fully known. For example, a gas detector might identify a few substances in production while leaving other components undisclosed or unspecified. An industrial hygienist may know that something is present in the process, but not necessarily which compounds could be released into the workplace air. This uncertainty can make the initial sampling process more complicated.
Instead of selecting one sampling method, several may be needed. Pumps can be set up with different sampling media for different groups of chemicals, and samples then need to be sent to a laboratory for analysis. The approach can be thorough, but it can also take time and become expensive when there are many potential contaminants to investigate.
This is where real-time FTIR can be useful as a screening tool.
How does real-time FTIR screening work?
Fourier-transform infrared spectroscopy (FTIR) works by measuring how infrared light is absorbed by molecules in a gas sample. Different compounds produce characteristic infrared spectra, like a fingerprint, which can be compared with reference spectra to determine which substances may be present.
Depending on the instrument configuration and available reference library, FTIR can measure multiple compounds at the same time and several gases can be analyzed from the same spectrum.
For example, Gasmet’s GT5000 Terra can quantify up to 50 gases at the same time, and identify over 5000 gases from the same sample data.
For an industrial hygienist, one of the practical advantages of this is that the measurement can be performed directly in the workplace, and results can be seen while the sampling is taking place. Instead of waiting for laboratory results before deciding what to investigate next, the screening measurement shows which compounds are present.
This can be particularly useful when investigating processes where chemical compositions are proprietary, evolving, or not fully disclosed, such as manufacturing sectors, pharmaceuticals, and emerging technology fields like semiconductor production.
Can FTIR replace conventional exposure sampling?
No. Real-time FTIR complements established exposure sampling methods. Used early in an assessment, it shows which compounds are present, so confirmatory sampling can be targeted.
A typical workflow could look like this:
Screen first → identify potential compounds → investigate further → confirm with established sampling methods.
A single measurement can answer a specific question, but repeated FTIR screening can provide a broader picture of a workplace process. Measurements taken at different production areas, under different operating conditions, or at different times can be compared to identify recurring patterns. If the same compounds repeatedly appear around a particular process, that information can help focus further exposure assessments.
This is also where real-time measurements differ from traditional laboratory sampling or simple detectors. Conventional samples provide detailed results for a defined sampling period and location, while real-time FTIR instruments can show how concentrations change while a process is running and results can also be reviewed and compared later. That can help answer questions such as:
- Does a chemical appear only during a particular part of a process?
- Does the concentration change when production conditions change?
- Is a reading isolated or does the same pattern occur repeatedly?
- Where in the process does the highest concentration occur?
That additional context helps when deciding what to sample and where, and it is what makes exposure sampling more targeted. Screening narrows down which substances need further investigation, instead of sampling for every chemical that is suspected. This reduces unnecessary sampling, saving time and resources.
For example, an industrial hygienist may use real-time FTIR to screen several locations around a process, identify a small number of compounds of interest, and then perform conventional personal or area sampling specifically for those compounds. This can also make laboratory resources easier to manage and potentially reduce the cost of investigations where broad initial sampling would otherwise be required.
Limitations and where FTIR fits in the industrial hygienist’s toolbox
There are also practical considerations. Using FTIR and interpreting the results require trained users who understand both the technology and the industrial hygiene context. Results are read against occupational exposure limits, process conditions and the limitations of the measurement itself. The table below summarizes the complementary roles of real-time FTIR screening and conventional sampling:
| Conventional sampling | Real-time FTIR screening | |
| Best for | Quantifying compounds you already know to look for | Finding out which gases are present when composition is unclear |
| Results | After laboratory analysis | On site, while sampling takes place |
| Compounds covered | Defined by the selected sampling method | Many gases at once, matched against a reference library |
| Output | Average over the sampling period | Concentration over time as the process runs |
| Formal assessment | Used for exposure assessments and compliance measurements | Complements established methods; guides confirmatory sampling |
Gasmet has taken these notions into account in the design of the GT5000 Terra and Calcmet software: the analyzer is designed for straightforward set-up and operation, while the simplified Calcmet Easy version lets less experienced personnel run measurements and view results, while the interpretation stays with the industrial hygienist.
Conclusion
Real-time FTIR monitoring removes the guesswork of identifying airborne chemicals. For workplaces where the chemical composition of emissions is uncertain, real-time FTIR can help bridge the gap between not knowing what gas components to look for and knowing what needs to be investigated further.
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Gasmet’s solution for industrial hygiene: ambient gas analyzer GT5000 Terra The portable and rugged design makes the GT5000 Terra ideal for identifying unknown airborne chemicals in industrial environments. Because FTIR measures multiple gases simultaneously in real time, industrial hygienists can quickly see what is present in the air without knowing in advance which compounds to look for. This helps reduce the risk of worker exposure to harmful substances, while easy operation supports continuous monitoring of workplace air and compliance with occupational exposure limits. As the range of chemicals used in industry continues to expand, fast and reliable screening will only grow in importance, with the GT5000 Terra playing a crucial role in safeguarding workers. |
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