Soroll, Salut, Covid-19

Barcelona is not being fumigated and the trails of the planes have nothing to do with the spread of the coronavirus delta variant

You have sent us an audio saying that many chemtrails are being performed in Barcelona, supposedly, fumigations with chemical substances released by airplanes, and that this coincides with the expansion of delta variant of SARS-COV-2. In this sense, we have also received a photograph that claims to have been taken at the end of June in Pallejà, 20 Km north of Barcelona, where one can see many trails of airplanes in the sky and you wondered why this happened. The trails left by planes depend, mainly, in the atmospheric conditions and have no relation with the pandemic. Moreover, the planes that fumigate (for instance, in agriculture) do not fly so high.

"They are performing a lot of chemtrails (chem, from chemical). This is what they are dropping from planes [...] They have been fumigating this week in Barcelona and they are announcing the delta wave in Barcelona"

Speculation about the trails left by airplanes goes back a long away, but behind these marks we see in the sky there is a physical explanation and a wide consensus within the scientific community that they are not fumigations, but particles of water in the form of ice crystals, which are more or less visible depending on the atmospheric conditions. According to a study from the University of California from 2016, 76 experts in atmospheric chemistry and geochemistry concluded that there is not any evidence about the existence of a large-scale atmospheric programme.

Therefore, it is also false that these traces left by airplanes are related to covid-19 infections. The accumulated incidence per 100,000 inhabitants to 21 July in the metropolitan area in Barcelona is 1,068 cases. According to the studies carried out to date and the experience of the epidemiological evolution of other countries such as the United Kingdom and India, the Delta variant of the virus is more easily transmitted and, therefore, the spread of the virus is higher. Moreover, it has been shown that most infections occur indoors, while it is much more difficult to become infected in open spaces, such as walking in the street. 

What are airplanes condensation trails

The traces left by planes when they fly are known as contrails or condensation trails. According to meteorologist Néstor Gómez, who works for TV3, this effect is caused by the difference in temperature between the particles released by the aircraft and the outside temperature at the altitude at which they are flying. Condensation trails start to form from an altitude of 10 kilometres, the same altitude at which aircraft fly, and at a temperature of between 30 and 40 degrees below zero. In this sense, when airplanes are in operation, they emit kerosene and water vapour at temperatures much higher than the temperature of the atmosphere, and condensation creates "ice crystals" that look like trails from the ground. 

Recently, the World Meteorological Organisation has established that if these condensation trails remain for more than 10 minutes without clearing, they are called homogeneous cirrus clouds, that is, a type of cloud created by humans. Condensation trails, therefore, are not harmful to health, what does have a negative impact on the planet and health are other particles emitted by aircraft. "The condensation trails are simple ice clouds, which cannot poison us" but "aircraft emissions are in themselves a source of greenhouse gases and pollutant particles that cannot be underestimated", according to the same report by the Spanish State Meteorological Agency (AEMET in Spanish).

The pollution generated by airplanes and which is harmful to the planet comes from other particles which are released by aircraft engines. According to the Spanish state Meteorological Agency, aircraft "emit water vapour, carbon dioxide (CO2), small amounts of nitrogen oxides (NOx), hydrocarbons, carbon monoxide, greenhouse gases and particles of silt and metal". Carbon dioxide and nitrogen oxide generated by human activity have increased the concentration of greenhouse gases in the atmosphere over the last two decades, which is causing global warming and climate change, according to an article published in the Journal of Scientific Research & Reports, but it does not influence the creation of condensation trails, as the same AEMET report explains.

The warmer it gets, the longer it takes for the condensation trails to disappear

The length and duration of these trails that we see in the sky vary depending on the wind and the atmospheric conditions in those altitude levels, according to meteorologist Gómez. For example, from an altitude of 5,000 metres we can find winds of over 150 km/hour, known as jet streams, which, if they are strong, the condensation trail will fade more quickly than if the streams are soft.

The atmospheric conditions are also important. If the atmosphere is dry when an airplane passes over it, there will be no condensation trail; however, if the atmosphere is wet, condensation will take place. Another conditioning favouring the formation of trails is the wind direction. With southerly or warmer winds it is much more likely to see contrails, whereas with northerly or colder winds, these trails are less likely to appear. One technique to know when it is more likely to see condensation trails is to look at the sky: when the sky is completely blue the trails will be seen less frequently, while if it is whitish it is more likely to see them. Therefore, when the atmosphere is humid and a long condensation trail has been created and, in addition, there is little or very weak wind, they will last longer, up to 24 hours.

Global warming makes the observation of trails more likely

According to Néstor Gómez, it is true that we can observe more and more trails, but this is due to the human effect: “We are making the atmosphere more and more humid, and this makes the effects of trails last longer”. Moreover, the number of airplane flights has also increased a lot in the last 10 years. From 2010 to 2019 there has been a 72% increase in the number of flights at Barcelona-El Prat airport, including passenger, operational and cargo flights. If we look at the difference between June 2020, marked by the covid-19 restrictions, and June 2021, flights have increased by 78%, but have not yet recovered the frequency with which they circulated before the pandemic.

In this sense, Gómez gives three reasons by which the fumigation theory is not credible. First, if an object is thrown from 10,000 meters high, it will not fall vertically due to the presence of the strong winds found at these altitudes. This was seen in the eruption of the volcanoes in Iceland, when a 10 km high cloud was created and spread across Europe. Secondly, if viruses were to be released, it is very unlikely that they would withstand such low atmospheric pressure. Thirdly, and as an example, the spraying that is done in the agricultural world to prevent pests in the fields is carried out with planes flying at an altitude of approximately 10 metres, because if they were sprayed at 10 km they would not be effective.

In the specific case of Pallejà, Verificat has contacted the town council and the local police and they have confirmed that they have no record of more planes than usual passing through the municipality. There is also no airfield in the area and because of its proximity to El Prat airport it is likely that planes arriving or departing from Barcelona fly over this area. On the airport’s official website, by means of the use of "WebTrak", you can see the activity of planes taking off and landing at Barcelona airport in real time and over the last month. Another website that offers information on flights that are taking place live around the world is Plane Finder, which also has the option of looking at the routes of the last 14 days. In both cases, frequent flights can be spotted flying over the surrounding area.


Aquest article és part del projecte "Les Mentides Amenacen la Salut", el primer portal de fact-checking de rumors sobre la covid-19 de Catalunya.

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