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:
The correct answer is:
d. the method produces direct-reading results.
Explanation:
Integrated air sampling is a widely used technique in industrial hygiene and environmental monitoring to assess airborne contaminants over a period of time. This method helps to determine the average concentration of pollutants such as gases, vapors, dust, or fumes in a workplace or environment.
Let’s analyze each option:
a. It involves the passage of a known volume of air through an absorbing or adsorbing medium.
This is true. Integrated sampling requires drawing a specific volume of air through a collection medium, such as a filter, sorbent tube, or impinger, which traps the contaminants. The volume of air is carefully measured to calculate the concentration of contaminants per unit volume of air.
b. The desired contaminants are removed from the air during a specified period of time.
This statement is correct. The air is passed continuously or intermittently over the sampling period, and contaminants are captured or absorbed by the medium. This duration can vary from minutes to hours, depending on the monitoring goal.
c. The contaminants of interest are collected and concentrated over a period of time.
This is accurate. Integrated sampling collects contaminants cumulatively, allowing for detection even when airborne concentrations are low. The collection over time concentrates the pollutants onto the medium, making it possible to analyze small amounts effectively.
d. The method produces direct-reading results.
This is incorrect. Integrated sampling does not provide immediate (direct-reading) results. Instead, the sampling media collected over the period must be sent to a laboratory for analysis, often using techniques like gas chromatography or spectrophotometry. The results reflect the average concentration over the sampling period rather than instantaneous readings.
Summary:
Integrated air sampling is a time-weighted method to measure average airborne contaminant concentrations by collecting pollutants on a medium over time. It requires laboratory analysis after sampling, so it does not produce immediate, direct-reading results. Direct-reading instruments (like real-time gas monitors or photoionization detectors) provide instantaneous readings but are different from integrated sampling method.