Two days ago, a man in his seventies came to the booth with two younger men, probably his children or grandchildren, to exchange Omani rials into baht," he said, adding the man he saw matched the news description of the infected patient.
When he heard the news of the Mers infection yesterday through social media, Mr Tanid was immediately worried, as he had handled the money given to him by the man.
Meanwhile, Nattada Devamat, a travel agent working in the same street, said she disinfected her office several times yesterday, especially after dealing with clients. She also plans to purchase a surgical mask.
"I wouldn't walk through crowded streets in that area these days," she said, adding jokingly that she even feared walking past Bumrungrad Hospital, where the infected patient was admitted on Monday before being transferred to Bamrasnaradura Infectious Diseases Institute in Nonthaburi on Thursday.
According to Ms Nattada, most tourists from the Middle East currently in Thailand are medical tourists. The remainder have returned home for Ramadan.
"The disease could spread very easily, even outside the Nana area," she said, adding that she wishes more information would be given to the public.
Her comments echoed those of Mr Tanid, who would like to see signs providing all information about Mers being put up in the area. He considered Nana particularly at risk since many travellers staying there come from the Middle East.
"I hope the Ministry of Public Health is giving us accurate information as well, and that it doesn't hide the truth," Mr Tanid said.
Each day, over 100 customers come to the currency exchange booth, said Mr Tanid, who says he feels particularly exposed. If the disease spreads, we might even have to shut down temporarily, he said.
Australian tourist Tracy Julian said she was not even aware of the infection. "But now that I know, I feel concerned," she added. The owner of the hotel where the infected Omani traveller is said to have stayed refused to comment.