The Pollution Control Department (PCD) has warned people not to insert used face masks into plastic drinking water bottles after more than 20 people became infected with Covid-19 in Nakhon Ratchasima.
The PCD blames the infection on virus-contaminated water bottles.
PCD director-general, Atthapol Charoenchansa, said large numbers of face masks have been used during the pandemic and the Ministry of Natural Resources and Environment has issued a set of guidelines for proper disposal of used face masks.
However, some households place used masked in drinking water bottles, mistakenly believing that this would be for the sake of the safety of rubbish collectors, Mr Atthapol said.
"This is a misunderstanding," he said.
If the bottles are not incinerated, rubbish collectors have to remove the used masks from the bottles, putting them at serious risk of contracting the disease, he said.
A 73-year-old man who made a living by collecting and selling recyclable waste in Muang district was reportedly infected with Covid-19 after coming into contact with plastic bottles contaminated with the virus.
The man reportedly spread the disease to 20 people, including family and neighbours.
As many as 4.4 billion drinking water bottles are manufactured annually, and uncontaminated bottles are recycled, according to the PCD.