AQS Data Collection & Analysis 3

Question 1

What is the correct isokinetic sampling rate condition required during EPA Method 5 particulate matter stack sampling?

Accepted Answer

Sample flow rate must equal stack gas velocity at the probe tip ±10%

Answer

Isokinetic sampling requires the gas velocity entering the probe nozzle to equal the local stack gas velocity within ±10%, preventing size-selective particle bias.

Question 2

In the design of a passive diffusion tube network for NO2 monitoring, what exposure period is typically used?

Accepted Answer

2–4 weeks

Answer

Passive NO2 diffusion tubes are typically deployed for 2–4 weeks to collect a time-integrated sample representative of average ambient concentrations over that period.

Question 3

Which quality control parameter defines the maximum allowable difference between collocated monitor measurements expressed as a percentage?

Accepted Answer

Relative percent difference (RPD)

Answer

Relative percent difference (RPD) is the standard QC metric for comparing collocated measurements, calculated as the absolute difference divided by the mean of the two values times 100%.

Question 4

What is the primary advantage of using a continuous emissions monitoring system (CEMS) over periodic stack testing?

Accepted Answer

CEMS provide real-time, 24/7 emissions data for operational control and compliance

Answer

CEMS continuously record emissions around the clock, enabling real-time operational adjustments and providing a complete compliance record unlike periodic stack tests that only capture a snapshot.

Question 5

A wind rose diagram is primarily used in air quality studies to show:

Accepted Answer

The frequency and speed of winds from each compass direction

Answer

A wind rose is a circular statistical chart displaying the frequency distribution of wind directions and associated wind speeds at a monitoring site over a specified period.

(AQS) Air Quality Specialist Certification Practice Test

(AQS) Air Quality Specialist Certification Practice Test

AQS Data Collection & Analysis 3