BEIJING, Feb. 12 (Xinhua) -- The China National Environmental Monitoring Center (CNEMC) on Wednesday refuted data on a foreign weather website that allegedly pointed to heightened levels of sulfur dioxide around Wuhan, the epicenter of the coronavirus outbreak, as "seriously distorted."
Data provided by Windy.com, a Czech company providing weather forecasting services, reportedly showed that sulfur dioxide levels in so-called "contaminated zones" of Wuhan had topped 1,500 micrograms per cubic meter early on Sunday.
Some foreign media reports picked up the incorrect data, used it as an indicator of mass cremations of bodies or medical waste, and accused China of a major cover-up.
After cross-checking Windy's off-the-charts data with those collected by monitoring centers in Wuhan run by third-party companies, the CNEMC found that the sulfur dioxide concentration in the reported areas did not even exceed 8 micrograms per cubic meter during that time.
Satellite data also showed Wuhan's peak reading of the pollutant did not surpass 11.5 micrograms per cubic meter from Feb. 3 to 9, and the city did not see a spike in the substance when compared with surrounding areas.
Instead, the city registered a marked drop in key air pollutants. From Jan. 24 to Feb. 10, the concentration of small and breathable particles known as PM2.5 dropped by 38 percent year on year, while PM10 and sulfur dioxide plunged by 42 percent and 22 percent, respectively.
An unnamed CNEMC official highlighted Windy's data deviation when it comes to measuring sulfur dioxide levels in other Chinese cities.
For example, a monitoring center in Dongsi in downtown Beijing showed an average reading of 15 micrograms per cubic meter on Tuesday, while data offered by Windy.com averaged 212 micrograms per cubic meter.
Data gathered by techniques such as satellite retrieval and model simulation, both non-standardized monitoring methods, should be checked with actual monitoring on the ground and is meaningful only when its margin of error falls within a limited range, the official said.
"Windy's ground-level sulfur dioxide data was not calibrated with the actual data gathered by on-site monitoring in China, leading to figures 10 times or even 100 times greater than the actual amount," he said. "It is anything but precise."