Los Angeles once suffered some of the worst smog on Earth

Pineapple research helped scientists solve Los Angeles' smog mystery

In the 1950s, chemist Arie Haagen-Smit applied methods he'd used studying pineapple plant chemistry to smog-filled air—discovering that sunlight reacting with car exhaust produced photochemical smog from hydrocarbons and nitrogen oxides, not factory smoke.

Photochemical smog forms when sunlight reacts with car and industrial emissions

The hazy phenomenon's name is a combination of "smoke" and "fog" and is composed of chemical pollutants that can cause eye irritation, lung damage and harm to crops. Smog buildup is more common in cities with sunny climates, minimal wind and surrounding mountains that trap these chemicals.

The Clean Air Act became the cornerstone of modern air pollution control

Passed in 1970 and strengthened through multiple amendments, the Clean Air Act authorizes the EPA to set national air quality standards, regulate industrial and vehicle emissions, and reduce pollutants such as ozone, sulfur dioxide, and lead.

How LA brought water to its booming population

By the turn of the 20th century, Los Angeles had grown from a dusty, crime-ridden pueblo into a thriving metropolis. The only problem was that it was growing too fast. Here's the story of how the booming town created a massive water infrastructure to redirect area rivers to its residents.

LA used to have one of the best mass transit systems in the country

A century ago, Los Angeles had one of the greatest urban transit networks in America. Today, driving in LA traffic can still be faster than taking the train. The city's rail design, which funnels traffic through a single point, fails to support a city with such a spread-out population.

Volatile chemical contamination can last in burn areas long after urban wildfires

Lead, arsenic, asbestos, and other chemicals have been found trapped in smoke-exposed rugs, couches, pillows, and other furniture that appeared otherwise undamaged from the 2025 LA wildfires. The gradual release of these substances has produced dangerous indoor air concentrations and contributed to increased emergency room visits and abnormal blood tests.

How Los Angeles got its palm trees

Los Angeles is known for its warm weather and palm trees, but the latter haven't always been part of the landscape. As Hollywood's movie industry grew, so did the number of palm trees. As this article points out, most of the city's palm trees were planted in the 1930s through an unemployment relief program.

In 1974, Los Angeles’s Community Analysis Bureau built a smart city

Los Angeles utilized aerial imaging and cluster analysis to gather and interpret civic data, leveraging surveillance technologies developed by the Department of Defense during the height of the Cold War. Instead of being used for military purposes, data insights helped direct social services to high-poverty neighborhoods.

The perplexing Battle of Los Angeles in 1942 generated swaths of UFO conspiracies

On Feb. 24-25, 1942, weeks after the Pearl Harbor attack, a US military radar warned of enemy aircraft. A citywide blackout went into effect, powerful searchlights were lit up, and US forces fired artillery at what they believed to be the enemy. However, no confirmed enemy planes were ever identified. Eyewitnesses reported seeing large objects flying overhead, and much of the public speculated about UFOs and extraterrestrial attacks.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

In the 1930s, New York banned buskers as part of an antinoise campaign

Mayor Fiorello LaGuardia was hoping to modernize the city and believed that street performers only crowded the streets and added to an annoying cacophony. Residents wrote to the mayor to protest the decision, arguing that buskers were appreciated by the public.

Cleveland's Cuyahoga River caught fire over a dozen times

Between 1868 and 1969, the Cuyahoga River in Cleveland caught fire at least 13 times due to oil and industrial waste. The 1969 blaze garnered national attention, prompting federal action and contributing to the creation of the EPA, which ultimately led to a successful cleanup of the river.

The history of Earth's breathable atmosphere, made possible by photosynthetic bacteria

Between 3.2 billion and 2.8 billion years ago, threadlike microorganisms called cyanobacteria began consuming available water vapor, carbon dioxide, and sunlight to produce oxygen. However, molecules released from Earth's interior by volcanoes consumed this oxygen via chemical reactions, preventing it from accumulating until volcanism had sufficiently decreased about 2.4 billion years ago.

The 1969 Santa Barbara oil spill galvanized the modern environmental movement

In January 1969, an oil platform off the coast of Santa Barbara ruptured, releasing roughly 3 million gallons of crude into the Pacific. The spill killed over 10,000 seabirds, dolphins, and seals, coating 35 miles of coastline.

Louisiana's 'Cancer Alley' has cancer rates 50% above the national average

Due to its proximity to Gulf oil production, an 85-mile stretch of highway linking Baton Rogue, Louisiana, and New Orleans is home to 25% of the country's petrochemical manufacturing. It's also one of the most polluted regions of the US, with cancer rates at 50% above average.

As of 2024, 13 states have plans to phase out gas-powered cars

In 2022, California adopted the Advanced Clean Cars II Act, which requires all new passenger cars, trucks, and SUVs sold to produce zero emissions by 2035. Other states adopted similar laws, joining more than 50 countries with phaseout plans.

How Monet’s paintings changed the way we see London

Between 1899 and 1901, legendary French Impressionist painter Claude Monet produced over 100 paintings of London consistently shrouded in fog. Art historians claim this series left a permanent mark on how we perceive the capital city, inevitably layered in obscuring and dramatic mist. See some of the paintings and read more here.

The Hollywood sign originally said 'Hollywoodland'

The original sign, which was only intended to be up for 18 months and erected around 1903, advertised a new housing development in the Hollywood Hills. In 1949, the Hollywood Chamber of Commerce shortened it to "Hollywood."

Watch a visualization of New York City's greenhouse gas emissions

About 1.72 tons of carbon dioxide-equivalent gases are released into the atmosphere every second in the Big Apple, enough to fill a balloon 33 feet across at standard pressure and 59 degrees Fahrenheit. After a day, the spheres would pile up into a pyramid whose base spans from the bottom of Manhattan to the south of Central Park.

70 years ago today, city officials in Santa Cruz, California, banned rock 'n' roll to protect its youth from corruption after witnessing a 'provocative' concert the night before.

Abandoned Detroit: the decline of America's car mecca

Detroit, Michigan, began as a fur trading post in the 1700s but would become the world epicenter of car manufacturing in the 1900s after Henry Ford developed his paradigm-shifting assembly line at a plant there. Racial tensions, a lack of economic diversification, and poor leadership would plunge the city into poverty and decay in the late 1900s, culminating in a 2014 bankruptcy. Browse the somber images of the city's abandoned spaces here.

Hundreds of vulnerable Chicago residents died in 1995 during a long-lasting heat wave

Eric Klinenberg wrote a book diving into the specifics of the heat wave. His book, detailing the stories and context fueling more than 700 deaths during just one summer week, helps readers understand how social infrastructure lapses, power outages, and ineffective heat responses led to so many deaths.

An oxygen tank explosion forced Apollo 13 to abort its moon landing

The 1970 mission—intended to be the third lunar landing—forced astronauts Jim Lovell, Jack Swigert, and Fred Haise to focus solely on their survival. They engineered a makeshift filter to handle the carbon dioxide they produced, which exceeded the lunar module's capacity.

Why people hated permanent daylight saving time in 1974

Messing with the amount of daylight each day has consequences, as America found out in 1974 when it first passed all-year daylight saving time. See why it was revoked less than a year later.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

The Airstream surged in a postwar road trip boom

Wally Byam invented the Airstream in the late 1920s, but it took off following World War II, when more affordable automobiles allowed families to venture out into an expanding network of state and national parks. Airstream enthusiasts sometimes traveled in caravans, camping in front of famous scenery, like the Pyramids at Giza.

The first sushi bar in the US opened in the 1960s in Los Angeles

Kawafuku opened in the city’s Little Tokyo neighborhood in 1923 and installed its sushi bar in the mid-1960s. The restaurant primarily sourced local seafood, including abalone, though it also imported fish from Japan, attracting many Japanese expatriates.

The Punch: Tomjanovich and Washington both still feel the pain from that terrible moment

In the NBA of the 1970s, cocaine use was prevalent and fights were a regular occurrence. On one early December in 1977, a fight broke out between the Lakers and the Rockets. Read this gripping LA Times story from 1985 that recounts a near-fatal punch thrown by Laker forward Kermit Washington and the devastating consequences paid by Houston Rocket forward Rudy Tomjanovich.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

See the most iconic photos from four decades of LIFE magazine

When a Paris department store hesitated to sell Estée Lauder's perfume, she 'accidentally' broke a bottle, causing the smell to spread throughout the store and shoppers to start asking to buy the scent.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

View the ten deadliest tornadoes in US history.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Graffiti dates back to at least ancient Pompeii, where citizens scrawled messages to one another on public walls

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

Dorothy's famous entrance into Oz in 'The Wizard of Oz' relied on analog tricks, including a body double and sepia-toned paint, as much as it did on technology

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.