Sign In or Create an Account.

By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy

Climate

Wednesday Was the Worst Day for Wildfire Pollution in U.S. History

The finding by Stanford researchers confirms the danger — and lack of precedent — for the East Coast’s ongoing wildfire smoke crisis.

The Chrysler Building.
Heatmap Illustration/Getty Images

Wednesday, June 7, was by far the worst day for wildfire smoke exposure in American history, subjecting more people to greater amounts of soot and ash than any previous day on record, according to a new and rapid analysis conducted by Stanford researchers.

The finding confirms the danger — and lack of precedent — for the ongoing wildfire smoke crisis, which has smothered the northern and eastern United States in an acrid haze. Since Monday, a strong low-pressure system has fanned dozens of wildfires in northern Quebec, then blown the resulting smoke into North America’s most densely populated corridor, covering New York City, Philadelphia, Washington, D.C., and Toronto.

Even as the smoke moved in, it made history. Tuesday became the country’s third-worst day for wildfire smoke on record, according to research from the same Stanford team. Only two days in September 2020 — when vast wildfires sheathed California, Idaho, and the Pacific Northwest in smoke — had exposed more Americans to higher intensities of toxic particulate matter.

Wednesday smashed those records. By the late afternoon, New York and New Jersey’s sky had turned a pungent orange, and their air quality fell to “very unhealthy” or even “hazardous” levels for all groups, the worst category. The rest of the Northeast and Mid-Atlantic faced similar or only slightly better conditions, and wildfire smoke at least somewhat afflicted virtually everywhere between Minneapolis, Atlanta, and Boston.

Stanford chart.Stanford.

The vast geographic sweep of the smoke — and the fact that it was so intense in the country’s biggest city — obliterated the old record. The country’s previous worst day for smoke exposure was September 13, 2020, when nearly 35 million Americans were exposed to more than 50 micrograms per cubic meter of microscopic soot and ash. That is five times worse than what the World Health Organization considers safe.

But on Wednesday, roughly 62 million Americans — nearly one in five — were exposed to such high levels of particulate matter.

Get one great climate story directly in your inbox every day:

* indicates required
  • It was “just a massive, awful event, with highly populated areas getting hit with unprecedented levels of pollution,” Marshall Burke, an economist and professor at the Stanford Doerr School of Sustainability, said on Twitter. He leads the school’s Environmental Change and Human Outcomes Lab, which conducted the research.

    The study encompassed data from 2006 to 2023. The researchers studied which days were worst on a population- and exposure-adjusted basis. In other words, on which days in history were the most Americans subjected to the most intense amounts of wildfire smoke?

    Because the U.S. population has grown over time, and because wildfires have enlarged over the past few decades, it is unlikely that any days prior to 2006 saw so many Americans exposed to so much smoke. Most of the record days in the data set have happened since 2018.

    With the new record in place, Tuesday falls to the fourth-worst day for wildfire smoke on record.

    Speaking earlier this week, Burke said that what made this event so distinct from previous ones is that the wildfire smoke hit the country’s largest and most populated cities. “It’s mainly due to the East Coast having so many people. It’s New York, Boston, D.C., Detroit. Out West, our cities are just smaller,” he told me.

    Read more about the wildfire smoke engulfing the East Coast:

    Wednesday Was the Worst Day for Wildfire Pollution in U.S. History

    The 5 Big Questions About the 2023 Wildfire Smoke Crisis

    Nowhere Is ‘Climate Proof’

    When There’s Smoke, Getting Indoors Isn’t Enough

    How Many People Will This Smoke Kill?

    You’re out of free articles.

    Subscribe today to experience Heatmap’s expert analysis 
of climate change, clean energy, and sustainability.
    To continue reading
    Create a free account or sign in to unlock more free articles.
    or
    Please enter an email address
    By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy
    Adaptation

    Why Renters Have to Fight for Their Right to Air Conditioning

    The Pacific Northwest has become the unlikely vanguard in the movement to protect renters from extreme heat.

    Drawing a line on eighty degrees.
    Heatmap Illustration/Getty Images

    Washington State’s 2026 legislative session ended not with a bang, but with an alarm. On a drizzly mid-March evening before adjourning for the year, lawmakers filed out of the capitol having narrowly averted a special session over a data center tax break bill. “Someone or something” had set off the rotunda’s fire alarm, according to a local news outlet; returning after the brief delay, legislators cast their final vote, approving the state’s $79.4 billion spending plan.

    The alarm was, in many ways, a fitting end to the state’s adrenaline-pumping 60-day short session, which saw 1,669 new bills introduced. Most were DOA due to time and ever-present budget constraints. Among the casualties was HB 2265, a bill to “protect tenants from periods of extreme heat” by extending a landlord’s responsibilities to include adequate cooling in rental units alongside the usual standbys of basic habitability, heat and hot water.

    Keep reading...Show less
    Electric Vehicles

    London’s Police Cars Are Going Electric With the Help of AI

    The Metropolitan Police Service signed a deal with BetterFleet to manage the complicated logistics.

    A police car and a lightning bolt.
    Heatmap Illustration/Getty Images

    Police officers can’t be stuck waiting for their black-and-whites to recharge when an emergency call comes in. That urgency makes it especially tricky to transition their fleets away from fossil fuels and the lightning-fast gas fill-ups that get cars back on the road.

    But some cities and departments have begun to make the move, aided by artificial intelligence models to manage their many vehicles and ensure electric cars can do not just the next job, but every job. Around the world, trucking companies, buses, municipal vehicles, and other huge fleets want to go electric to save money on fuel and maintenance, and they’re looking to AI to give them the confidence to take the plunge.

    Keep reading...Show less
    Blue
    AM Briefing

    A Rare Earths Civil War

    On Last Energy’s milestone, California CCS, and RFK Jr. vs. microplastics

    A mining truck.
    Heatmap Illustration/Getty Images

    Current conditions: The summerlike heat in the Northeast is set to drop by double digits as cold Canadian air blows southward, sending temperatures in Boston as low as 50 degrees Fahrenheit by Saturday • Temperatures are nearing 100 degrees in Cordoba, Spain, as Western Europe’s record-breaking heatwave continues • Juba is also nearly 100 degrees as heavy thunderstorms roll into the capital of conflict-riven South Sudan.


    THE TOP FIVE

    1. America’s two rare earths champions are fighting each other

    Last year, in a move so bold it made Biden administration officials jealous, President Donald Trump took an equity stake in MP Materials, making the federal government the largest shareholder in the United States’ only active domestic rare earths producer. The deal became a trend, with the U.S. government taking minority ownership stakes in at least a dozen more companies that produce or process critical minerals, of which China controls the global supply. In January, USA Rare Earth, a manufacturer of rare earth magnets that aims to eventually mine and process fresh ore in Texas, became the second large rare earths-focused company in the Trump administration’s portfolio. Now America’s two champions in the war against China’s metal monopolies are instead battling each other. On Wednesday afternoon, the Financial Times reported that MP Materials had filed a lawsuit against USA Rare Earth, accusing its rival of “stealing” its technology for making the permanent magnets that go into everything from phones and electronics to electric vehicles to fighter jets. “USA Rare Earth has repeatedly failed to meet its commercial and performance targets and is now resorting to stealing technology to dig itself out,” MP Materials alleged in a complaint filed last week in Texas court. In response, USA Rare Earth said: “MP Materials’ complaint has misrepresented our company, our culture, and our people, and we will defend ourselves vigorously.”

    Keep reading...Show less
    Yellow