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 commonly used method in occupational and environmental hygiene for assessing air quality, especially for detecting contaminants like gases, vapors, and particulates. It allows for an accurate estimation of average exposure over a specific period of time. However, one of its limitations is that it does not provide direct-reading results. Let’s analyze why each option is or isn’t correct:
Option a: It involves the passage of a known volume of air through an absorbing or adsorbing medium.
This statement is true. Integrated air sampling typically uses filters, sorbent tubes, or impingers to trap airborne contaminants. A calibrated pump draws a specific volume of air through the sampling medium, which captures the contaminants of interest.
Option b: The desired contaminants are removed from the air during a specified period of time.
This is also correct. The sampling process occurs over a defined time (e.g., 8 hours), and during this period, contaminants are continuously collected from the air onto or into the sampling medium.
Option c: The contaminants of interest are collected and concentrated over a period of time.
This is true and is one of the primary benefits of integrated sampling. By collecting air over time, even low concentrations of contaminants can be detected after analysis, because they have been concentrated on the medium.
Option d: The method produces direct-reading results.
This is false, and therefore the correct answer. Integrated air sampling does not provide immediate results. After the air sampling period ends, the collected samples must be sent to a laboratory for chemical analysis using techniques such as gas chromatography, mass spectrometry, or spectrophotometry. This process can take hours or even days before results are available.
In contrast, direct-reading instruments (e.g., photoionization detectors, real-time aerosol monitors) provide instantaneous readings of air contaminants but may be less precise or less sensitive over long sampling periods.
Summary:
While integrated air sampling is excellent for accurate, time-weighted exposure assessments, it does not provide real-time or direct readings, making option d the correct exception.