Which monitoring method is commonly used for NOx and O3, and what do they measure?

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Multiple Choice

Which monitoring method is commonly used for NOx and O3, and what do they measure?

In ambient air monitoring, different pollutants are measured with methods tailored to what those gases do. For nitrogen oxides (NOx), chemiluminescence is used because NO reacts with ozone to produce light, and the brightness of that light is proportional to the amount of NO (or total NOx after converting NO2 to NO). For ozone (O3), UV photometry is standard because ozone strongly absorbs ultraviolet light around 254 nm; the amount of light blocked is proportional to the ozone concentration. So the combination of chemiluminescence for NOx and UV photometry for O3 is the typical pairing. The other methods mentioned are for particulate matter or are not the standard ambient method for NOx or O3.

In ambient air monitoring, different pollutants are measured with methods tailored to what those gases do. For nitrogen oxides (NOx), chemiluminescence is used because NO reacts with ozone to produce light, and the brightness of that light is proportional to the amount of NO (or total NOx after converting NO2 to NO). For ozone (O3), UV photometry is standard because ozone strongly absorbs ultraviolet light around 254 nm; the amount of light blocked is proportional to the ozone concentration. So the combination of chemiluminescence for NOx and UV photometry for O3 is the typical pairing. The other methods mentioned are for particulate matter or are not the standard ambient method for NOx or O3.

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