All of the following is correct regarding integrated air sampling except that …
a. it involves the passage of a known volume of air through an absorbing or adsorbing medium.
b. the desired contaminants are removed from the air during a specified period of time.
c. the contaminants of interest are collected and concentrated over a period of time.
d. the method produces direct-reading results.
The Correct Answer and Explanation is:
Correct Answer: d. the method produces direct-reading results.
Explanation:
Integrated air sampling is a widely used method in industrial hygiene and environmental monitoring for assessing the presence of airborne contaminants. This method involves collecting air samples over a set period of time and analyzing them later in a laboratory to determine the concentration of specific substances. Let’s examine why each statement is either correct or incorrect:
a. It involves the passage of a known volume of air through an absorbing or adsorbing medium.
✅ Correct.
This is a fundamental aspect of integrated air sampling. A calibrated pump is used to draw a specific volume of air through a medium—such as a filter or a sorbent tube—that either absorbs or adsorbs the airborne contaminants.
b. The desired contaminants are removed from the air during a specified period of time.
✅ Correct.
During the sampling period (which may range from minutes to several hours), contaminants in the air are captured by the collection medium. This time-weighted process is important in evaluating average exposure over a work shift or environmental condition.
c. The contaminants of interest are collected and concentrated over a period of time.
✅ Correct.
Integrated sampling collects contaminants gradually, concentrating them on the medium so they can be accurately measured in the lab. This enhances the detection of low-level exposures that might be missed in short-term or instantaneous measurements.
d. The method produces direct-reading results.
❌ Incorrect.
This is the exception and the correct answer. Integrated sampling does not provide immediate results. After sampling, the medium must be sent to a laboratory for analysis using techniques such as gas chromatography, spectrophotometry, or mass spectrometry. In contrast, direct-reading instruments (like real-time gas detectors or particulate monitors) provide immediate on-site readings without lab processing.
In conclusion, while integrated air sampling is highly accurate and useful for time-weighted exposure assessment, it does not produce direct-reading results. This makes it unsuitable for situations that require immediate data, such as emergency response scenarios.