Which U.S. cities are the smog champions? Take the quiz!


A hazy blanket hangs over a city. It's not mist or fog: It's smog. How much do you know about this form of air pollution? What's in it? What causes it? Which cities have it worst? What city has the cleanest air? Breathe deep -- then take the quiz.

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Question 1 of 20

Where was the term "smog" coined?

Hong Kong
Los Angeles
New York

... During the early 1890s, the word "smog" was used to describe the combination of smoke and fog in London. The contemporary use of "smog" refers to pollutants, primarily ground-level ozone.


Question 2 of 20

Ground level ozone is not natural, like the helpful ozone in the upper atmosphere. At ground level it is created by chemical reactions between VOCs (volatile organic compounds) and _______.

carbon dioxide
carbon monoxide
nitrogen oxide

... Nitrogen oxides and VOCs react, forming ozone in the presence of sunlight. The oxides come from such sources as car exhaust, power plants, chemical plants, refineries and industrial boilers.


Question 3 of 20

The Clean Air Act was passed in 1970. How much have emissions decreased in the last 40 years?

60 percent
40 percent
20 percent
10 percent

... Air pollution has decreased between 1 and 3 percent annually since the act went into effect, resulting in a 40 percent decrease overall.


Question 4 of 20

According to the American Lung Association, for 2012, which American city has the highest level of ozone in the air?

Los Angeles
Washington, D.C.

... The Los Angeles-Long Beach-Riverside area of California is number one on the list. In fact, California has nine cities in the top 10.


Question 5 of 20

Which American city is the cleanest when considering year-round particle pollution (acids, organic chemicals, metals, soil and dust)?

Boise, ID
Colorado Springs, CO
Flagstaff, AZ
Santa Fe, NM

... According to the American Lung Association, in 2012 the Santa Fe-Espanola area of New Mexico had the cleanest air. Cheyenne, Wyoming came in second.


Question 6 of 20

Heavy smog is linked to all of the following EXCEPT ________.

heavy traffic
high temperatures
strong wind

... Smog forms faster from car emissions on hot and sunny days. Calm winds allow smog to hover over a city for days.


Question 7 of 20

Most American cities with populations greater than __________ experience problems with smog.


... To some degree, ground-level ozone has presented problems to American cities with populations of more than 250,000 people.


Question 8 of 20

About how many million Americans live in cities where the ground-level ozone is above the acceptable health safety levels?


... Heavy smog affects about 90 million Americans on a regular basis. It can cause breathing problems, asthma and lowered resistance to colds and respiratory infections.


Question 9 of 20

Which federal department establishes acceptable levels of ozone, nitrogen oxides, and particulates in the air?

Centers for Disease Control
Council on Environmental Quality
Department of Health and Human Services
Environmental Protection Agency

... The Clean Air Act outlines the Environmental Protection Agency's (EPA) responsibilities for improving America's air quality.


Question 10 of 20

Which of the following is NOT a way that individuals may help improve air quality?

combine errands run by car
inflate tires properly
"top off" the gas tank when filling it
use public transportation

... Overfilling a tank can lead to gas spillage, which will evaporate into the air. In addition, overfilling the tank does not leave enough room for gas expansion, which can increase emissions.


Question 11 of 20

Children are in the most danger from ground-level ozone because _________.

their lungs are smaller
their lungs are still developing
their lungs have less capacity
children and adults are equally susceptible to the effects of smog

... Children's lungs are still developing until they are about 10 years old. Also, children generally spend more time outside than adults.


Question 12 of 20

How does wind affect ozone?

It cannot move it.
It can move smog great distances.
It can only move smog short distances.

... Wind can carry smog a significant distance; that's how ozone levels can be high even in the country.


Question 13 of 20

Which of the following tree species is extra-sensitive to ground-level ozone?


... Trees that are especially vulnerable to ozone include cottonwood, black cherry, ponderosa pine and quaking aspen.


Question 14 of 20

Which of the following is an effect that ozone can have on some kinds of vegetation?

damage leaves
decrease defenses against disease
reduce ability to make food
all of the above

... Sensitive plants can be affected in many ways, such as reducing abilities to make and store food, injuring leaves and increasing vulnerability to diseases and insects.


Question 15 of 20

Which of the following building materials has been manufactured to improve air pollution levels?

roof tiles

... Roof tiles are being manufactured that neutralize nitrogen oxides emitted from cars. The tiles contain titanium dioxide, which reacts in sunlight to turn nitrogen oxide into calcium nitrate.


Question 16 of 20

According to the United Nations, urban areas worldwide account for what percentage of harmful emissions?

50 percent
60 percent
70 percent
80 percent

... Although cities cover only 2 percent of all the land on Earth, they are responsible for about 80 percent of emissions.


Question 17 of 20

Building new or widening existing highways creates "__________" traffic.


... When increased access to highways results in induced traffic, many people stop using mass transit, and carpoolers stop sharing rides. Increased traffic brings more smog.


Question 18 of 20

According to a study released at the 2012 World Economic Forum in Davos, Switzerland, which country has the worst air pollution in the world?


... Out of 132 countries, India was rated as having the worst air quality. The study was conducted by Yale and Columbia universities in conjunction with other institutions.


Question 19 of 20

The Chinese government did not formally admit that the country had a smog problem until 2011, though the air pollution had caused __________.

cancellations of national sporting events
flight cancellations
numerous automobile accidents

... Flights out of Beijing International Airport have been canceled due to air quality problems. This has far-reaching effects, since Beijing is a busy hub.


Question 20 of 20

The worst environmental disaster in history occurred in __________.

Kanpur, India
Ahwaz, Iran

... During the "Killer Fog" of 1952, approximately 12,000 Londoners died from smog in just four days. Visibility was reduced to one foot.


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