In the midst of what the World Health Organisation calls an "infodemic" of fake news around the COVID-19 coronavirus outbreak, British tabloid newspapers published images they suggested was evidence of corpse burning in Wuhan.
Although the conditional tense was used, they inferred "satellite images" from the windy.com showed high levels of sulphur dioxide (SO2) in Wuhan and Chongqing, both cities quarantined at the epicentre of the outbreak.
The Sun newspaper ran a story suggesting Beijing was "burning the evidence". The headline read: with China accused of major coronavirus cover-up as chilling satellite pics 'show extent of corpse burning in Wuhan’.
But both suggested that these high levels of SO2 could have come from an unusual crematorium activity in both cities. Other media followed suit.
The claim pushed China's air quality office to issue a statement via China's Ministry of Ecology and Environment.
It said: "After careful confirmation, we found that the SO2 rise published by windy.com was a 'serious distortion' and its statistics could not be trusted."
According to their data, a concentration of between 4 and 8 μg/m3 was recorded on Sunday and not 1,300 μg/m3 as shown by the application.
Where did the sulphur dioxide claim come from?
A tweet from Twitter account @inteldotwav, with just over 16,000 followers, posted a thread including what looked like an impressive image on February 8.
It claimed to show dangerously high levels of SO2 near Wuhan and Chongqing.
The person behind the tweet left interpretation of what the high levels of SO2 meant open to the reader,
It was suggested it could be a power plant, burning garbage or animal carcasses, and "the third and most morbid: that bodies are being burned on the outskirts of the city, that the numbers of victims are much higher than what the Chinese Communist Party is reporting, and that things are really, really bad."
The tweeter confirmed he saw the rumours on the internet and decided to do his own "investigation". However, his method proved to be misleading.
In recent days, some media have reported that Wuhan's crematoria are operating 24/7 based on an interview with an employee, interviewed reportedly obtained by The Epoch Times, a conservative and anti-communist media of the Chinese community in the US. Other experts outside China also question the accuracy of the official death toll.
So what's the truth?
It is true that data on windy.com shows extremely high levels of SO2 in both cities.
But little or nothing allows us to establish a relationship with the alleged unbridled activity at the city's crematoria.
Sulfur dioxide is naturally emitted by volcanoes. According to the WHO, the main human source of SO2 emissions is the combustion of sulphur-containing fossils used for domestic heating, electricity generation and motor vehicles as well as the burning of waste and the decomposition of organic matter.
Models used for forecasts are not "satellite measures"
The data on windy.com is not based on satellite images, as claimed by the Sun tabloid newspaper in its headline.
Instead, they are based upon forecasts based on NASA's GEOS-5 model, which, according to the US agency itself, often give significantly higher results than observations.
The models are not updated to take into account episodes like the coronavirus. They're based on "emissions inventories", for example, the probability of pollution levels based on known sources of emissions.
They take into account the usual sources of emissions of an area: factories, power and heating plants, and cross-references them with meteorological variables. In other words, NASA would have had to introduce a "burning human bodies in crematoria" parameter. This is very unlikely.
NASA has not responded to Euronews' requests for comment on this.
This type of forecast uses satellite data, but, in general, satellites are not able to detect small sources of sulphur dioxide such as factories or crematoria. They do accurately measure more intense phenomena such as volcanic eruptions.
So, if there were an intense, unusual emissions activity due to crematoria, it wouldn't be shown on these models.
Wuhan and Chongqing always have high levels of SO2 using the NASA model
The earth.nullschool application uses the same GEOS-5 NASA model. But it also has an archive of measures. At random, we went to February 14, 2019 - long before the world knew about the existence of a new type of coronavirus - and obtained even more impressive values of 1,583 µg/m3.
The values change depending on where we place the cursor.
The same goes for Chongqing, where, at random, we get levels of over 1,000 μg/m3 last year, or even in 2018.
This means the "forecasts" of these platforms are an interesting and useful indicator, and, certainly, Chongqing and Wuhan suffer from poor air quality, but this is approximative data to be taken into perspective, not a scientific measure or proof.
An Italian chemistry professor has made a rough calculation for the website open.online, and he estimates that to get to those levels of SO2 Wuhan would have to burn about 30 million bodies. That's unlikely, to say the least.
Factories and atmospheric conditions
Experts consulted by Euronews believe that the levels observed are not particularly alarming in one of the world's most polluted country.
They say that high concentrations in a particular place may be related to atmospheric conditions. Indeed, last weekend in Wuhan it was cold, about 4-5 degrees — increasing the probability of people using heating — and not very windy, which can increase concentrations.
East of Wuhan, where the large cloud of SO2 was shown, there is a large coal-fired power plant that is identified in NASA's catalogue of sources of sulphur dioxide emissions, as researcher Iolanda Ialongo told us.
Anu-Maija Sundström, an air quality expert from the Finnish Meteorological Institute, pointed out that at a quick glance, neither the air quality indices nor the SILAM model showed anything exceptional in the SO2 levels of Wuhan.
In short, this looks like just another more example of the difficulty of separating rumours and misinformation in a subject as sensitive as the coronavirus. Many take advantage of the traditional opacity of the Chinese authorities to multiply the most gruesome speculations.
The World Health Organization itself or the major social networks and Internet platforms have created special pages to try to stop false rumours about COVID-19.