A power plant burns coal containing sulfur. Which gas forms from that sulfur and leaves directly in the stack gas?

A car idles inside an attached garage with the door closed. Which pollutant from incomplete combustion can build up indoors?

Fuel burned at high temperatures in buses and utility boilers emits which ozone-forming precursor?

Small piston-engine planes are the largest source of one criteria air pollutant in the US. Near an airport used heavily by these planes, which pollutant is of greatest concern?

Wind carries dust from an unpaved road beside a construction site. What pollutant is directly added to the air?

A furniture factory uses solvent-based coatings. Which class of emissions can evaporate from the coatings and help form ozone?

On a hot sunny afternoon, NOx and VOC emissions react over a city. Which pollutant is likely to increase?

Smoke rises from a wildfire near a community. Which criteria pollutant is a major component of the smoke?

Air monitoring is placed beside a battery-recycling facility. Which pollutant should the monitors specifically measure?

A poorly vented gas stove operates in a home. Which combustion pollutant can be released into the indoor air?

An industrial boiler burns heavy fuel oil with a high sulfur content. Which pollutant is expected directly from this fuel combustion?

A diesel truck produces visible soot in its exhaust plume. What type of air pollutant does the soot represent?

Ground-level ozone forms after NOx and VOCs react in sunlight. Is it a primary or secondary pollutant?

A coal plant releases sulfur dioxide from its stack. Is the emitted sulfur dioxide primary or secondary?

Sulfate particles form in the atmosphere after sulfur dioxide reacts with other chemicals. Are the sulfate particles primary or secondary?

Tailpipe exhaust releases carbon monoxide from incomplete combustion. Is that carbon monoxide primary or secondary?

Dust is blown directly from an unpaved road into the air. Is this particulate matter primary or secondary?

Nitric acid forms after nitrogen oxides react in the atmosphere. Is the nitric acid primary or secondary?

Over a forest, VOCs released by trees react with ozone and form tiny particles in the air. Are these particles primary or secondary?

A smelter emits lead-containing dust directly into the air. Is that airborne lead primary or secondary?

Which pollutant forms carboxyhemoglobin in blood and reduces the body's oxygen intake?

During a summer photochemical smog episode, an athlete develops shortness of breath and more frequent asthma attacks. Which pollutant most directly causes this effect?

Which pollutant is linked to cardiovascular harm, including heart attacks and strokes, as well as asthma attacks?

Acid deposition damages buildings and other materials downwind of coal-burning power plants. Which emitted pollutant is a principal cause?

A child with asthma has respiratory symptoms near a busy highway. Which traffic-related pollutant is especially associated with respiratory effects?

Which air pollutant is associated with lowered IQ and behavioral problems in children?

A national park has reduced visibility because of haze. Which pollutant is the main cause of this visibility impairment?

A community reports increased asthma symptoms near fossil-fuel combustion sources. Which pollutant is a respiratory irritant associated with these symptoms?

Sensitive leaves in a forest are damaged during the growing season by a pollutant carried in photochemical smog. Which pollutant caused the damage?

A generator runs in an enclosed space, and people report headache, dizziness, and confusion. Which pollutant explains these symptoms?

Emissions from cars react in the atmosphere and contribute to acid deposition that harms lakes and materials. Which precursor pollutant is involved?

A person breathes wildfire smoke and has an asthma attack. Which pollutant in the smoke is most likely to have caused the respiratory harm?

In PM2.5, what does the 2.5 indicate?

An air monitor collects only particles 10 micrometers in diameter or smaller. Which pollutant category does it measure?

Which particle would be classified as PM10 but not as PM2.5?

One monitor reads 16 µg/m³ PM2.5 and another reads 10 µg/m³. By how much is the first reading higher?

A sample contains 0.020 mg of particulate matter per cubic meter of air. What is this concentration in µg/m³?

Why do PM2.5 particles generally pose a greater health risk than larger particles?

Use the bar graph. Which monitoring site has the highest PM2.5 concentration?

Use the line graph. On which day was the PM2.5 concentration lowest?