NEW DELHI — A grayish haze filled the park as the yoga practitioners gathered for their daily exercise early Thursday morning. Anywhere else the haze might have been fog or mist, but Delhiites know better: For the second time in as many weeks, the smog was so severe that the city took the emergency step of closing schools.

But the yoga devotees saw no reason to stay home — and no reason to wear anti-pollution masks. “I’ll look like a fool if I wear a mask,” said R.L. Khattar, ­a ­92-year-old resident of a nearby ­lower-income neighborhood, prompting laughter from the others. Delhi’s bad air had given him a recurring cough and feelings of breathlessness. But a mask makes Khattar feel “claustrophobic.”

Standing nearby, Prem Gupta, 52, concurred. No one in his family wears a mask, including his children. “Pollution won’t stop if you wear a mask, so what’s the point?” he asked.

Despite living with some of the world’s worst air, very few residents of India’s capital wear anti-pollution masks, which can filter the vast majority of harmful particles if worn correctly. The paucity of such masks stands in stark contrast to cities such as Beijing, another megacity known for acute smog, where it is not unusual to see people wearing them.

But Delhi’s doubts about masks may be fading.

Pollution here spikes every autumn as a toxic stew of pollutants — industrial emissions, road dust, car exhaust and soot from agricultural fires — settles over the city. Despite various efforts to combat pollution, Delhi just recorded its longest stretch of hazardous air quality since public records began, according to IQAir, a purifier and monitoring firm. Authorities have closed schools for four days this month and banned half the city’s cars from the roads every other day.

The reasons people in Delhi are reluctant to wear masks are complex. For many of the city’s poorer residents, even the cheapest disposable pollution mask, which costs around $1.25, may be prohibitive. But other factors are also at play, including a lack of awareness of the health risks posed by air pollution. Even those who know the dangers say masks are uncomfortable, socially awkward or inadequate to the enormity of the problem.

Now there are signs that such attitudes are beginning to shift. This year, for the first time, the Delhi state government announced that it would distribute 5 million anti-pollution masks to students across the city. The masks — dark gray with red adjustable straps — began arriving in schools at the start of the month. Disposable pollution masks are showing up at small general stores, companies have offered them as part of sales promotions, and some employers are giving them to their staff.

“For the first time ever, people are dialed in and listening,” said Jai Dhar Gupta, 47, a businessman who distributes the Vogmask brand in India. He said that he had sold more than 100,000 masks this year, exhausting the company’s India inventory and forcing them to get stock from China.

Gupta got into the mask business in 2014 after he suffered a collapsed lung, something he blames on air pollution. The least expensive mask he sells retails for about $23. “As far as I am concerned, I am solving the rich man’s problem,” said Gupta, who is also active in a citizen initiative to combat pollution. “I feel guilty, but at least I am solving some part of the problem.”

Still, mask wearers remain the exception. On Wednesday, as the city’s air quality began to deteriorate once again, legal journalist Murali Krishnan wrote on Twitter that he was standing in a corridor of the Supreme Court wearing a pollution mask and drawing stares. The particulate matter most harmful to human health had just jumped to more than 20 times the limit recommended by the World Health Organization. “Hello, I should be staring at people for not wearing a mask,” he wrote.

Shikha Adlakha, the mother of two daughters in Delhi’s public schools, said the local government had taken a good step by distributing masks to students. But her eighth-grader doesn’t find hers comfortable and wears it only when her mother is around. Adlakha said her younger daughter, who is in second grade, does wear her mask, as “she listens to me [and] thinks wearing it is cool.”

Researchers at the University of Chicago conducted surveys around mask-wearing behavior among 3,500 of Delhi’s poorest residents. They found that the awareness of the harm pollution causes is still relatively low and that social norms may discourage people from wearing masks.

Even if local and federal authorities take strong actions to combat Delhi’s bad air, it “would take a number of years for pollution to come down,” said Kenneth Lee, one of the researchers. “In the meantime, defense is sort of important.”

One of the reasons for the higher prevalence of pollution masks in China is experience, said Christopher Dobbing, who lived in Beijing for seven years and founded Cambridge Mask, a company that makes anti-pollution masks that retail in India starting a $10 a piece. In China, people wear surgical masks when they are ill to prevent their germs from spreading, a practice that intensified during outbreaks of the SARS virus. The concept of wearing masks in public is “already ingrained in the culture,” he said.

Meanwhile in Delhi, a sense of futility and despair enters the conversation around pollution on days like Thursday. Early in the morning, Shrikant Malik, 21, a national medalist in track and field, was training with several other sprinters in Delhi’s Lodhi Garden. A musty haze hung over the park, and the air quality index was in the “hazardous” category as measured by the U.S. Embassy. None of the young athletes were wearing masks.

Masks are too uncomfortable, Malik said. He added that when the pollution is extreme, he feels a burning in his throat and begins to cough. Living in Delhi, “you feel like you’re closed in a room,” Malik said. It is only after leaving the city that “you feel like you’ve gone outside.”

Tania Dutta contributed to this report.