BBC Homepage
  • Skip to content
  • Accessibility Help
  • Your account
  • Notifications
  • Home
  • News
  • Sport
  • Weather
  • iPlayer
  • Sounds
  • Bitesize
  • CBBC
  • CBeebies
  • Food
  • More menu
More menu
Search BBC
  • Home
  • News
  • Sport
  • Weather
  • iPlayer
  • Sounds
  • Bitesize
  • CBBC
  • CBeebies
  • Food
Close menu
BBC News
Menu
  • Home
  • InDepth
  • Israel-Gaza war
  • War in Ukraine
  • Climate
  • UK
  • World
  • Business
  • Politics
  • Culture
More
  • Tech
  • Science
  • Health
  • Family & Education
  • In Pictures
  • Newsbeat
  • BBC Verify
  • Disability
  • BBC Trending

Chemtrails: What's the truth behind the conspiracy theory?

  • Published
    23 July 2022
Share page
About sharing
Aircraft vapour trails over Jerusalem in 2021 (file image)Image source, AFP
Image caption,

Aircraft vapour trails - there's nothing sinister about them

By Alistair Coleman
BBC Monitoring, Disinformation specialist

The word "chemtrails" has trended on sunny mornings this summer - but what's the truth behind the conspiracy theory?

Look up at a clear blue sky and you might see puffy white trails behind aeroplanes.

They are made up mostly of water and are called contrails or vapour trails, but a growing number of people falsely believe they are evidence of something sinister going on.

Some think malign forces are spraying the population with dangerous chemicals - so-called chemtrails - for purposes that are neither entirely clear nor consistent.

A surge in conspiratorial thinking following the Covid pandemic along with the summer travel season and clear skies mean the once obscure chemtrails theory is now being promoted by major influencers.

What are contrails?

Contrails are formed when water vapour and fine soot particulates from burning jet fuel freeze into ice crystals. In low air humidity, the crystals just dissipate. In higher humidity, they persist, and end up creating visible vapour trails over large areas of sky.

Those humidity differences explain why some aircraft are seen producing vapour trails while others do not.

High humidity means that vapour trails can last for long periods and become thin layers of cirrus clouds, Met Office meteorologist Aidan McGivern told the BBC. Cirrus clouds are short, detached and hair-like and are found at high altitudes. It is unlikely that any of these purported chemicals in the clouds would even reach ground level because they are at such high altitudes, he said.

One persistent belief among followers of the theory is that early morning chemtrails encourage greater cloud cover later in the day - but this can be explained by the natural process of convection. This is the result of the sun warming the ground, causing warm air to rise and condense into clouds later in the day, the Met Office says.

How did the conspiracy theory begin?

The idea that governments or shadowy forces are routinely spraying the planet with chemicals from scheduled passenger flights took hold in the 1990s.

Initially, believers claimed sprays containing a toxic metal, barium, were being used to either pacify or reduce populations.

But the idea evolved along the way, meaning today there are several strands of the chemtrail theory.

Vapour trails behind an Airbus A-380 airliner over the Netherlands in 2019 (file image)Image source, Getty Images
Image caption,

A scheduled passenger aircraft, showing vapour trails from its jet engines

In recent years, followers have expanded their accusations, claiming the contrails are being used to spread Covid-19, external, distribute vaccines, external, initiate "mind control", reduce the population or vaguely promote a "new world order".

False allegations have trended so frequently this year that fact-checking charity Full Fact has posted 10 debunks since April, external.

A bowl of white vinegar
Image caption,

Bowls of vinegar are left out by some followers of the theory

Chemtrail influencers are highly active on platforms such as Facebook and Telegram, where they discuss the day's alleged "spraying" and track aircraft. Some suggest putting a bowl of white vinegar outside, saying that this clears "chemtrailed" skies.

Chemtrail social media groups also often contain anti-vaccine posts and promote climate change denialism, feeding off an increase in conspiracy thinking during the Covid-19 pandemic, external, and the rise of the QAnon conspiracy theory during the Trump presidency.

  • The people who think governments control the weather

  • The truth behind the new climate change denial

  • How our climate has changed since the 1976 heatwave

The phenomenon is international, with followers across UK, Europe, Australia and the Americas - in fact, anywhere under which commercial or military aircraft fly. And it is backed by a few celebrities and popular social media influencers.

Aircraft vapour trails of scheduled services flying into Heathrow over the former BBC Monitoring building in Reading
Image caption,

Vapour trails on a summer morning over Caversham Park in Reading, caused by ice crystals condensing

What's the truth?

Like many persistent conspiracies, the chemtrails idea comes with a kernel of truth.

In the 1950s and 1960s, decades before the conspiracy theories were born, much of Britain was sprayed with airborne chemicals, external in a series of secret germ warfare tests. And in 1950, San Francisco was sprayed with a chemical agent from a ship to gauge the effects of a bioweapon attack on a populated area, external.

Chemtrails conspiracy theorists point to such secret experiments to bolster their cause. But their claims blow the historical record out of all proportion, as they claim we are constantly - and very visibly - being deliberately sprayed with tonnes of dangerous chemicals, for an ever-shifting variety of reasons.

  • The War on Truth podcast: 'Covid was a hoax and so is the Ukraine war'

  • Death by Conspiracy? podcast: Did conspiracies lead to Covid deaths?

Like other conspiracy theorists, chemtrail enthusiasts also latch on to news events to push their agenda, for instance in messages like this posted during the recent UK heatwave:

A tweet alleging that the July heatwave was part of a UK government plot. Used with Twitter account holder's permissionImage source, TWITTER/MAZE OF DECEPTION

There is no evidence the claim in the tweet is true, nor does it explain the record temperatures across Europe at the same time.

The British Airline Pilots Association (BALPA) told the BBC it is aware of these chemtrail theories with "no evidential basis".

"The distraction of these false theories detracts from what really matters and from areas that we believe should be further studied," it added.

There is concern that high altitude jets contribute to long-term climate change - not through any deliberate release of secret chemicals, but instead through contrails in a mechanism known as "radiative forcing", external.

BALPA told the BBC it is campaigning for a comprehensive research trial into the effect aviation has on pollution, not CO2, as well as the impact contrails are having on a changing climate.

Aircraft vapour trails over Reading, UK in 2014

Related topics

  • BBC Monitoring
  • Conspiracy theories
  • BBC Verify
  • Air travel

More on this story

  • How do temperatures compare with the 1976 heatwave?

    • Published
      19 July 2022
    1976 heatwave
  • Is this the new climate change denial?

    • Published
      17 November 2021
    the sun
  • The people who think governments control the weather

    • Published
      31 January 2018
    Chemtrails billboard

Top stories

  • Live. 

    Aid drops a 'distraction' with Gaza starvation deepening, UN agency boss says

    • 3495 viewing3.5k viewing
  • Security tightens as Donald Trump plays golf at Turnberry

    • Published
      34 minutes ago
  • Gregg Wallace 'sorry' but says he's 'not a groper'

    • Published
      13 hours ago

More to explore

  • Why we need to talk about periods, breasts and injuries in women's sport

    Chloe running towards the camera with her arms to her sides, wearing white shorts and white sports bra with her England shirt twirled up in her right hand, screaming with joy, blonde hair flying
  • How reality TV changed the way we think - for the better

    A treated image showing an old TV screen with a close up eye
  • Sleep, exercise, hydrate - do we really need to stick to recommended daily doses?

    A woman wearing black leggings and pink athletic shoes, standing on a set of black steps. One foot is placed on a higher step while the other remains on a lower one, suggesting an exercise or stretching.
  • ​​What is inside the GHF food aid box being distributed in Gaza?

    An image showing a young man carrying an box of aid with the GHF logo emblazoned on it. He is wearing a dark shirt with Nike Air written on it. Several other people are walking alongside him, and the image is imposed over the BBC Verify branding and colours.
  • School-leavers losing their lives for Russia in Putin's war with Ukraine

    Separate photos of two boys, one in a white judo outfit and the other a black tracksuit top
  • French pledge to recognise Palestine is a gamble - so will Starmer follow suit?

    Sir Keir Starmer and French President Emmanuel Macron
  • How Epstein case is tearing apart Maga's online conspiracy wing

    Red hats with Donald Trump's Maga logo are handed out at an event
  • Why is River Island in trouble?

    A group of young people walk past a River Island store with sale signs in the window
  • News Daily: Our flagship daily newsletter delivered to your inbox first thing, with all the latest headlines

    A promo promoting the News Daily newsletter - a graphic of an orange sphere with two concentric crescent shapes around it in a red-orange gradient, like a sound wave.
loading elsewhere stories

Most read

  1. 1

    Security tightens as Donald Trump plays golf at Turnberry

  2. 2

    'My dad started spying on my mum' - the drugs causing sexual urges

  3. 3

    World's thirst for matcha dries up global supplies

  4. 4

    Sleep, exercise, hydrate - do we really need to stick to recommended daily doses?

  5. 5

    Why we need to talk about periods, breasts and injuries in women's sport

  6. 6

    Gregg Wallace 'sorry' but says he's 'not a groper'

  7. 7

    School-leavers losing their lives for Russia in Putin's war with Ukraine

  8. 8

    'We were sure we wouldn't bump into each other at uni'

  9. 9

    Five killed as Ukraine and Russia trade drone attacks

  10. 10

    The Traitors Prom, and WWE Unreal: What's coming up this week?

BBC News Services

  • On your mobile
  • On smart speakers
  • Get news alerts
  • Contact BBC News

Best of the BBC

  • New drama from writer Jimmy McGovern

    • Attribution
      iPlayer
    Unforgivable
  • The Bafta award-winning comedy returns

    • Attribution
      iPlayer
    Such Brave Girls
  • An epic road trip across Vietnam

    • Attribution
      iPlayer
    Top Gear
  • Amol Rajan and Billy Bragg chat politics

    • Attribution
      iPlayer
    Radical with Amol Rajan
  • Home
  • News
  • Sport
  • Weather
  • iPlayer
  • Sounds
  • Bitesize
  • CBBC
  • CBeebies
  • Food
  • Terms of Use
  • About the BBC
  • Privacy Policy
  • Cookies
  • Accessibility Help
  • Parental Guidance
  • Contact the BBC
  • Make an editorial complaint
  • BBC emails for you

Copyright © 2025 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.