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

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. 

    Trump says no deal but 'progress made' after Ukraine talks with Putin

    • 15000 viewing15k viewing
  • No ceasefire, no deal. What summit means for Trump, Putin and Ukraine

    • Published
      2 hours ago
  • 'A long way for nothing?' BBC correspondents on Alaska meeting

    • Published
      1 hour ago

More to explore

  • 'Putin is a master of persuasion' - BBC correspondents discuss summit strategy

    Anthony Zurcher on the left and Steve Rosenberg on the right.
  • 'Ukraine's fate in their hands' and 'Praying for peace'

    A composite image of the front pages of the Daily Mail and the Daily Mirror on 16 August 2025
  • PC catches 'icky' catcallers on undercover jogs

    Image shows two females running. One is dressed in all black. She has a black short-sleeved top and black leggings on with a grey running vest over the top. She has black Nike trainers on. Her hair is in a bun. The second officer has turquoise trainers on. Burgundy shorts and a brown long-sleeved tight fitting top. She has a grey running vest over the top. Her hair is in a ponytail. They are in a carpark with four cars parked alongside them. Behind them are a number of trees, grass and a main road.
  • Bowen: Netanyahu is presiding over a divided Israel - the fault lines are now chasms

    Two images: Benjamin Netanyahu on the right and on the left, relatives and supporters of Israeli hostages held captive hold their portraits during a protest in Tel Aviv
  • He found a bomb under a playground - and there were 176 more

    A composite image of Steven Parkinson and some of the bombs he discovered under a playground in Scotts Park
  • 'Tell someone about abuse' urges victim of prolific catfishing sex offender

    A mugshot of Max Hollingsbee is superimposed onto a graphic comprised of blue zero and one binary code numbers on a black background. Hollingsbee is a young man with wavy brown hair
  • Weekly quiz: Why were Italian restaurants in a rage about pasta?

    A woman with black nail varnish uses her fork to twist spaghetti in a bowl
  • 'We were never friends': A massacre on the eve of WW2 still haunts China-Japan relations

    An elderly man wearing a suit with an ear piece in his ear wipes tears off his face. Behind him more elderly men can be seen, slightly blurred
  • Government turns to TikTokers to advise on cosmetic surgery abroad

    A woman and a man in a split composite image showing TikTok influencers, the woman in a red spotty dress and the man in blue NHS uniform.
loading elsewhere stories

Most read

  1. 1

    No ceasefire, no deal. What summit means for Trump, Putin and Ukraine

  2. 2

    UK trade envoy resigns over northern Cyprus visit

  3. 3

    'Ukraine's fate in their hands' and 'Praying for peace'

  4. 4

    Blackpink: K-pop band make 'epic Wembley dream' come true

  5. 5

    The 104-year-old WW2 veteran who moved the Queen to tears

  6. 6

    Far-right Israeli minister taunts prominent Palestinian prisoner

  7. 7

    Topshop returns to the High Street, but can it get its cool back?

  8. 8

    Court temporarily bans arrivals at asylum hotel

  9. 9

    Iceland offers £1 reward for reporting shoplifters

  10. 10

    Sonic boom heard after RAF scrambled to incident

BBC News Services

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

Best of the BBC

  • The inside story of Rupert Murdoch’s empire

    • Attribution
      iPlayer
    The Rise of the Murdoch Dynasty
  • A galactic concert of planets and lightsabers

    • Attribution
      Sounds
    Proms 2025
  • New drama from writer Jimmy McGovern

    • Attribution
      iPlayer
    Unforgivable
  • A vigilante matriarch with her own dark secrets

    • Attribution
      Sounds
    Crime Next Door: The Ballad of Big Mags
  • 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.