50 free Pollution trivia questions with answers — science & nature quiz, new questions added Aug 2026.
Pollution killed about nine million people in 2019, one death in six, and most of that was the air. It is also older than you think: soot on cave ceilings, Roman lead in Greenland ice, and a 1306 royal ban on burning coal in London. These 50 questions cover the science and the history: point versus nonpoint sources, PM2.5, photochemical smog, acid rain's pH, biomagnification and ocean acidification, forever chemicals and microplastics, plus the disasters that built environmental law: the Great Stink and the Great Smog, Donora, the burning Cuyahoga, Minamata, Love Canal, Bhopal, the Exxon Valdez, Lake Karachay and the Montreal Protocol. A few questions on the economics, too: externalities, Pigouvian taxes and the world's dirtiest industries. Every answer is cited to a page we checked. Play it solo, or print it for an environmental science class or Earth Day round.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Pollution coming from one concentrated site, like a factory, is called what?
Point source
Agricultural runoff and microplastics are the classic nonpoint sources.
Q 02Roughly how many people did pollution kill worldwide in 2019?
Nine million
That was about one in six deaths that year, roughly three-quarters of them from air pollution.
Q 03Which type of pollution caused about three-quarters of pollution deaths in 2019?
Air
Outdoor air pollution from fossil fuels alone is blamed for roughly 3.6 million deaths a year.
Q 04Before the 1860s, what did the word 'pollution' usually refer to?
Desecration of something sacred
Air pollution was instead called 'the smoke nuisance', 'the smoke evil' or even 'the smoke plague'.
Q 05PFAS compounds are informally known by what nickname?
Forever chemicals
Scientists in 2022 called PFAS pollution a newly crossed planetary boundary.
Q 06Photochemical smog forms when nitrogen oxides and hydrocarbons react with what?
Sunlight
That is why Los Angeles, sunny and car-choked, became the smog capital by the 1940s.
Q 07Particulate matter labeled PM2.5 is measured in what unit?
Micrometres
The number refers to particle size; PM10 is the coarser fraction.
Q 08Thermal pollution most often comes from using water as what?
Coolant in a power plant
Warm discharge changes the temperature of rivers and lakes downstream.
Q 09Which natural feature is among the most significant natural sources of pollution?
Volcanoes
Eruptions release carbon dioxide, sulfur dioxide, hydrogen sulfide and particles carrying arsenic, lead and mercury.
Q 10Which volcanic gas can kill humans at concentrations below one part per thousand?
Hydrogen sulfide
Sulfur dioxide harms animals and the ozone layer; hydrogen halides cause acid rain.
Q 11Americans are under 5% of the world's people but produce roughly what share of its CO2?
25%
They also generate approximately 30% of the world's waste.
Q 12In 2007, which country overtook the United States as the biggest producer of CO2?
China
Per capita it still ranked only 78th among nations at the time.
Q 13What are polychlorinated dibenzodioxins commonly called?
Dioxins
TCDD, one of them, contaminated Love Canal in New York for decades.
Q 14Which heavy metal is found in rechargeable batteries and is a frequent soil contaminant?
Q 21Which two pollutants are the main causes of acid rain?
Sulfur dioxide and nitrogen oxides
They react with water in the atmosphere to form sulfuric and nitric acids.
Q 22In environmental economics, pollution from manufacturing is an example of what?
A negative externality
Because the polluter doesn't pay the full cost, the good tends to be overproduced and underpriced.
Q 23What is a carbon tax an example of, in economic terms?
A Pigouvian tax
It prices the externality so the market reaches the socially optimal level of pollution.
Cadmium
Chromium, lead, arsenic and benzene round out the usual suspects.
Q 15Which 2001 book revealed industrial leftovers being recycled into fertilizer?
Fateful Harvest
The practice left soils poisoned with metals.
Q 16The 2017 Lancet Commission found pollution kills how many times more people than wars and violence?
15
It also found pollution deaths triple those from AIDS, tuberculosis and malaria combined.
Q 17In 2019, air pollution was blamed for 1.67 million deaths in which country?
India
That was 17.8% of all deaths nationally that year.
Q 18By about what percentage did US coal-pollution deaths drop between their 1999 peak and 2020?
95%
Plants closed or installed scrubbers, with the sharp decline starting after 2007.
Q 19What is the term for toxins becoming more concentrated up the food chain?
Biomagnification
Heavy metals like mercury become exponentially more concentrated at each trophic level.
Q 20Dissolved carbon dioxide causes which ongoing change in the world's oceans?
Acidification
It lowers the pH of seawater, threatening shell-building marine life.
Q 24Which industry topped Pure Earth's 2016 list of the world's most polluting?
Lead-acid battery recycling
Mining, lead smelting, tanning and artisanal mining filled out the top five.
Q 25Which English king banned the burning of mineral coal in London in 1306?
Edward I
The fuel was called 'seacoal' because it arrived by sea; 'coal' then meant charcoal.
Q 26What 1858 event on the Thames led to London's sewer system?
The Great Stink
It was one of the earliest extreme cases of urban water quality problems.
Q 27Which two US cities first enacted clean air laws in 1881?
Chicago and Cincinnati
Progressive reformers were also fighting street pollution from three million working horses.
Q 28How many horses worked in American cities in 1900, producing urine and manure?
Three million
The first generation to see cars replace horses called automobiles 'miracles of cleanliness'.
Q 29Which Pennsylvania town suffered a deadly smog event in the late 1940s?
Donora
Along with Los Angeles smog, it was a public reminder of industrial air pollution.
Q 30The Great Smog of 1952 prompted which landmark British law?
Clean Air Act of 1956
The smog killed at least 4,000 people; later estimates put the toll at 10,000 to 12,000.