High sulphur dioxide levels at the centre of the coronavirus outbreak could be a sign of mass cremations, it has been claimed.
Satellite maps in recent days have shown alarming levels of SO2 around Wuhan, the Chinese city where the outbreak began.
In addition, there were high sulphur dioxide levels in the city of Chongqing which is also under quarantine.
Scientists say that sulphur dioxide is produced when bodies are cremated, and also when medical waste is incinerated.
A Twitter user who investigated the maps suggested that dead bodies could be being burned on the outskirts of the city.
China has decreed that the bodies of coronavirus victims should be cremated in low-key funerals to prevent large public gatherings.
The country's National Health Commission said earlier this month that bodies should be 'cremated close by and immediately'.
On top of that, there have been repeated claims - albeit unverified - that officials are concealing a higher-than-reported death toll with mass cremations.
The high sulphur dioxide levels in Wuhan would be consistent with a high number of cremations in the city.
One map from Czech-based weather service Windy.com showed sulphur dioxide levels in Wuhan at a staggering 1,350 micrograms per cubic metre (µg/m3) over the weekend.
For comparison, the World Health Organisation (WHO) says that a dosage of 500 µg/m3 should not be exceeded for more than 10 minutes.
The UK government considers a 15-minute concentration of 533 µg/m3 to be 'high'.
According to the map, the SO2 levels were lower today but Wuhan and Chongqing still stood out compared to much of China.
Parts of Wuhan still showed concentrations above 500 µg/m3 on Monday, the map suggested.
Scientists say that cremating bodies releases SO2 along with other pollutants including nitrogen oxides.
The US Environmental Protection Agency says that burning medical waste can also cause sulphur dioxide emissions.
However, it is not certain that the high SO2 levels are related to the coronavirus crisis. The colourless gas is also produced by the burning of fossil fuels and other chemical processes.
The areas around Beijing and Shanghai, which are not in lockdown, also displayed high levels of SO2 today, although they were not as high over the weekend.
Wuhan remains in lockdown with 11million people in quarantine, meaning reports from the city are hard to verify.
The World Health Organisation says that high or prolonged exposure to sulphur dioxide can cause 'serious risks to health'.
The gas can play a role in health problems such as asthma, lung inflammation and reduced lung function, experts say.
'SO2 can affect the respiratory system and the functions of the lungs, and causes irritation of the eyes,' the WHO says.
'Inflammation of the respiratory tract causes coughing, mucus secretion, aggravation of asthma and chronic bronchitis and makes people more prone to infections of the respiratory tract.
'Hospital admissions for cardiac disease and mortality increase on days with higher SO2 levels.
'When SO2 combines with water, it forms sulphuric acid; this is the main component of acid rain which is a cause of deforestation.'
The death toll from the virus rose by 97 yesterday, the deadliest day since the outbreak began.
Another 3,062 cases were reported in China yesterday - an increase of 15 per cent compared to Saturday which put an end to a series of daily declines.
The latest surge in figures has dampened hopes that China's public health response might be working.
The rise in China's death toll comes as millions of people return to work today after an extended Lunar New Year holiday.
Roads in Beijing and Shanghai had significantly more traffic than in recent days and the city of Guangzhou was resuming normal public transport today.
However, the American Chamber of Commerce in Shanghai said 60 per cent of its member companies were planning mandatory work-from-home policies.
Tens of millions of people in Hubei province were not returning to work, as the province at the centre of the outbreak remained under lockdown.
China has built two hospitals for virus patients in Wuhan and sent thousands of extra doctors, nurses and other health care workers to the city of 1 million people.
Most access to Wuhan was suspended on January 23 and restrictions have expanded since then to cities with a total of 60million people.
China said today that 27 foreigners had been infected with the virus in the country, including two of the country's 908 deaths.
Two people have died outside mainland China, one in Hong Kong and the other in the Philippines, taking the global toll to 910.
More than 360 cases of the virus have been confirmed outside China, bringing the total to at least 40,531.
The fatality toll has passed the 774 people believed to have died in the 2002-03 SARS outbreak, another viral outbreak that originated in China.
The total of more than 40,000 confirmed cases of the new virus vastly exceeds the 8,098 sickened by SARS.
This article has been adapted from its original source.
© Associated Newspapers Ltd.