BANGKOK -- The severe air pollution blanketing the Thai capital has caught one of Japan's big electronics producers flat-footed and left one of Thailand's major retailers without enough designer air purifiers from the U.K.

Economic losses from the smog are estimated at 6 billion baht ($192 million) in January alone. But the haze, which has been coloring Bangkok's skyline since early January, has also been a boon to makers of face masks, Southeast Asia's largest ride-hailing service and to city's notorious sidewalk vendors.

"Simply put, sales (of air purifiers) are booming," said Masanori Iwanaga, managing director of Hitachi Sales (Thailand), the local unit of the Japanese electronics conglomerate.

Thailand's air purifier market is relatively small, but with Thais now worried about what they are breathing, many stores have run out of the appliances.

"Our sales are running at twice the levels of ordinary years," Iwanaga said. "We are ramping up production but are struggling to meet surging demand."

The Central Group, one of Thailand's main retail conglomerates, has also seen a rise in sales, according to President Yol Phokasub. Central Group stores have run out of air purifiers made by Dyson of the U.K., the senior executive said.

Face mask sales are also hot. So-called N95 respirators, masks approved by the National Institute of Occupational Safety and Health, are particularly popular. N95 certification is given to masks that can block at least 95% of 0.3-micron particles. Stores have sold out of N95 masks made by U.S. manufacturer 3M, and fakes are appearing along Bangkok streets.

Grab, Southeast Asia's leading coordinator of ride-hailing and food delivery services, was a bulk buyer of these masks. With demand for food deliveries on the rise, Grab Thailand in January distributed 3,000 N95 masks to motorcycle taxi drivers for a second consecutive year.

"We are committed to taking good care of our driver-partners," said Monrawee Ampolpittayanant, head of Public Affairs, Grab Thailand.

Grab is responding to Bangkok residents who have decided to forego eating at the inexpensive food stalls that dot the city and have their meals delivered to them. The Singapore-based company says the number of meal orders it handles has tripled since Bangkok's air became much more visible. The food delivery service operated by the Thai unit of Line has seen a 20% pickup in orders, according to local media.

The N95 masks may not be enough. The main building block of the capital's brown haze is PM2.5, atmospheric particulate matter with a diameter of less than 2.5 micrometers. These tiny particles pose the greatest danger to health due to their ability to lodge into people's lungs. They come from automobile and factory emissions as well as smoke from the burning of fields.

PM2.5 levels in the Thai capital started rising sharply in January and have remained well above World Health Organization limits in recent days.

The Thai government is attempting to chase some of the soot away by trying to generate artificial rain and asking factories to cut back their operations. But there has been no noticeable improvement, and experts say the particulate matter will remain until wind and rain chase it away.

The toxic smog prompted public elementary and junior high schools in Bangkok to close for a few days at the end of January. Authorities also urged people to curb the use of incense and refrain from celebrating the Lunar New Year, which came earlier this month, with fireworks.

Despite its poor air quality, Bangkok emerged as the top destination for Asia-Pacific travelers during this year's string of holidays, as measured by online booking agent Agoda. The Thai capital overtook Tokyo, which fell to No. 2 on the travel site's list of favored Chinese New Year destinations.

But the quality of Bangkok's air seems to have surprised some of the season's arrivals.

"I fled bad air in Beijing," said Zhou Ting Juan, a 32-year-old Chinese tourist who this year made her sixth trip to the kingdom, "and I didn't expect to see it in Bangkok. I am about to shorten my trip here and switch to Bali."

Chairat Trirattanajarasporn, president of the Tourism Council of Thailand, is concerned that the prolonged smog problem could harm an industry which accounts for 20% of the country's gross domestic product.

"In some countries," Chairat said, "they even order all trucks to wash away dust from wheels in order to prevent bringing more dust into the city. We should do so to protect people's health and protect our tourism industry."

Kasikorn Research Center, a research arm of Kasikornbank, warns that "if the air pollution problem persists, international tourists may decide to spend their holidays in other countries."

Kasikorn estimated economic losses in the form of opportunity costs -- benefits missed out on by choosing an alternative -- of at least 14.5 billion baht in the month of January. The University of Thai Chamber of Commerce estimated that the foul air cost the Thai economy 6 billion baht during January. It also expects these losses to increase if the problem air persists.

Scientists warn that Bangkok can expect the hazardous smog to at least return next year and likely for several years to come, especially if no long-term measures are taken.

"We have been warned of an incoming El Nino this year," said Pisut Painmanakul, an environmental scientist at Chulalongkorn University. "This means the weather will be very dry, and that means more bush fires will worsen the situation this year and next year."

Pisut added that El Nino patterns usually last for a few years.

El Ninos are irregular climatic changes in the equatorial Pacific region that have drastic knock-on effects across a wide swath of the globe.

The environmental scientist said Bangkok's traffic congestion and the city's large number of aging diesel-powered vehicles spew a lot of particulate matter. He added that Thailand has no laws barring these vehicles from operating in the city.