An elderly patient hooked up to a tangle of tubes lies struggling for breath in a Bangkok hospital as Thailand battles a "drastic increase" in respiratory problems caused by a spike in air pollution.
His wife holds his hand and strokes his face, with a nurse in blue scrubs listening to his chest through a stethoscope.
Every single breath is an exertion.
About 2.4 million people in Thailand have needed treatment for medical problems linked to air pollution since the start of the year, including nearly 200,000 this week alone, according to health officials.
Bangkok and the northern city of Chiang Mai were among the top 10 most polluted cities in the world on Friday, according to air quality monitoring firm IQAir.
Piamlarp Sangsayunh, a respiratory disease specialist at the Central Chest Institute of Thailand in Nonthaburi, says she has seen a "drastic increase in patients since February".
"The patients usually have respiratory problems like coughing and sore throats," she told AFP on Friday, adding that eye irritation is also common.
Elderly people are among the most vulnerable to air pollution, which can exacerbate existing conditions, sometimes requiring them to be put on oxygen machines, she said.
But she said those working outdoors -- such as Bangkok's vast army of street vendors and motorbike taxi drivers -- were the ones "on the front line" of the crisis.
- Toxic air -
Uraiwan Chantana, who sells fish balls on the street in Bangkok's central shopping district, said breathing in toxic air every day made her exhausted, but she could not shut her stall because she had no other way to earn money.
"I feel a burning pain inside my nose and I regularly cough," she told AFP.
"I feel out of breath when I climb stairs when I normally didn't."
World Health Organisation representative to Thailand Jos Vandelaer said air pollution was not solely a health issue but also dented economic productivity.
"If people are sick they can't go to work, there will be a reduction in economic activity," he told AFP.
The economic cost of air pollution in Thailand in 2019 was equal to $63.1 billion or 11 percent of gross domestic product, according to Kasetsart University environmental economist Witsanu Attavanich.
One of the biggest concerns are tiny particles known as PM2.5, smaller than the diameter of a hair, which can penetrate deep into the lungs and even reach the bloodstream.
According to IQAir, in 2022 the average PM2.5 concentration in Thailand was 3.6 times the WHO's annual air quality guideline limits.
"In the long term, there are more risks for respiratory infections... If people have asthma that can get worse, people can develop chronic lung diseases, even lung cancer," Vandelaer said.
"What is less well known is that this PM2.5 can cause cardiovascular diseases... increase the risk of a stroke or heart attack."
Air pollution was a factor in about 31,000 deaths in 2019 in Thailand according to WHO data.
Smoke from forest fires, farmers burning crop stubble, as well as vehicle emissions and heavy industry-generated fumes, are among the main causes of toxic smog in the kingdom.
The El Nino weather pattern is also exacerbating the haze problem in Southeast Asia, experts say.
Thailand is home to more than 70 million people and its poor air quality is a growing issue ahead of the country's May 14 election, with the incumbent government accused of not doing enough.
"We need to fix the problem at the roots, as a doctor I'm just on the receiving end dealing with the consequences," Piamlarp said.
Vandelaer said more regulation was needed to address fires and polluters, adding that individuals should also think about how their transportation and lifestyle choices affected air quality.
Bangkok motorcycle taxi driver Tip Panyangam, 59, said he often felt unwell from the smog despite wearing a double mask.
"I want the people in power to reduce it because I am worried about my health," he told AFP.