![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Module 6: Air Pollutants and Control Techniques - Ozone - Practice Problems
- Instructions:
- Answer these questions on a sheet of paper and check your responses against those provided below.
-
#1
- State whether each of the following statements about ozone is
true or false.
- Ozone imparts a reddish-brown color to smog.
- Even low ozone concentrations are associated with a variety of
adverse health effects in most people.
- At high concentrations, ozone is very toxic.
- Ozone is odorless.
- Ozone imparts a reddish-brown color to smog.
- Answer: i. False
- Ozone is a component of smog, but it is a colorless gas. Dimers of
nitrogen dioxide in the atmosphere contribute to the brownish color
of smog.
- Answer: ii. False
- Moderate ozone concentrations are usually associated with a variety
of adverse health effects.
- Answer: iii. True
- At high concentrations, ozone is very toxic.
- Answer: iv. False
- Ozone has an "electric discharge" type of odor.
Practice Problems
Formation Mechanisms
- Instructions:
- Answer these questions on a sheet of paper and check your responses against those provided below.
-
#1
- Which compounds are considered to be precursors for ozone in urban air masses?
-
- Answer: Nitrogen oxides, volatile organic compounds, and carbon monoxide are considered to be precursors for ozone in urban air masses. Because ozone forms as a result of photochemical reactions involving these precursor compounds, sunlight is an important and necessary factor in this process.
-
#2
- When are ambient ozone concentrations highest in the Northern hemisphere?
-
- Answer: May through September
- Ambient ozone concentrations are highest in the Northern hemisphere during the warm weather period from May through September.
-
#3
- What is the main factor limiting the formation of ozone in rural areas far from man-made sources of air pollutants?
-
- Answer: The availability of nitrogen oxides is the main factor limiting ozone formation in clean rural areas.
-
#4
- What are some of the major sources of nitrogen oxides, volatile organic compounds, and carbon monoxide that are believed to participate in ozone forming reactions?
-
- Answer: Some of the major sources of precursor gases include fossil-fuel-fired boilers, automobiles, and other mobile sources.
-
#5
- Will the minimization of ozone formation in urban areas by controlling the precursor gases have an adverse impact on the concentrations of beneficial ozone in the stratosphere?
-
- Answer: No
- The reactions responsible for the formation of beneficial ozone in the stratosphere are entirely different than those responsible for the formation of high ozone concentrations in the troposphere.
-
#6
- Are stationary sources and/or mobile sources major emitters of ozone concentrations in the troposphere?
-
- Answer: No
- The dominant sources of ozone in the troposphere are the photochemically initiated reactions between precursor compounds in the atmosphere.
Practice Problems
Control Techniques
- Instructions:
- Answer these questions on a sheet of paper and check your responses against those provided below.
-
#1
- How are ambient air concentrations of ozone controlled?
-
- Answer: Ozone forms in the atmosphere as a result of photochemical reactions of the precursor compounds: nitrogen oxides, volatile organic compounds (VOCs), and carbon monoxide. Therefore, regulations attempt to control the emissions of these precursor compounds from stationary and mobile sources.