ETC Air Quality & Emissions Monitoring 3

Question 1

Which precursor pollutants combine in sunlight to form ground-level ozone (O3)?

Accepted Answer

Volatile organic compounds (VOCs) and nitrogen oxides (NOx)

Answer

Ground-level ozone forms when VOCs and NOx react in the presence of sunlight through photochemical reactions, making these two pollutants the primary regulatory targets for ozone control.

Question 2

EPA Method 6 is used to determine the concentration of which pollutant in stack gas?

Accepted Answer

Sulfur dioxide (SO2)

Answer

EPA Method 6 is the reference method for determining SO2 emissions from stationary sources using a midget impinger collection system followed by barium-thorin titration.

Question 3

What is the primary purpose of a high-volume (Hi-Vol) air sampler in ambient air monitoring?

Accepted Answer

To collect a large volume of air through a filter to determine PM10 or TSP mass concentrations

Answer

Hi-Vol samplers draw large volumes of air (typically 1,100–1,700 m³ over 24 hours) through a weighed filter to gravimetrically determine TSP or PM10 mass concentrations.

Question 4

Under what condition would an environmental technician report an air monitoring instrument as 'out of calibration'?

Accepted Answer

When the instrument reading drifts more than the allowable tolerance from the certified reference standard value during a calibration check

Answer

An instrument is out of calibration when its response to a known reference gas or standard falls outside the acceptable drift tolerance specified in the QA/QC plan or method.

Question 5

What does an air dispersion model (such as AERMOD) primarily calculate?

Accepted Answer

Predicted pollutant concentrations at receptor locations downwind of emission sources

Answer

AERMOD and similar Gaussian dispersion models use source emission rates, meteorological data, and terrain to predict ground-level pollutant concentrations at specified receptor locations.

ETC - Environmental Technician Certification Practice Test

ETC - Environmental Technician Certification Practice Test

ETC Air Quality & Emissions Monitoring 3