BENGALURU, India — For people across South Asia, especially in northern India, Diwali celebrations coincide with the return of hazardous winter air, raising concerns about how to celebrate safely.

Winter also brings severe smog to parts of Pakistan and China, where warmer air can act as a lid, trapping colder air and pollution near the ground. In eastern Europe, burning coal and wood to heat homes also adds to winter pollution. Western Hemisphere countries, meanwhile, face their own seasonal air-quality problems, as summer wildfires send smoke across vast areas of the United States and Canada.

Experts say no matter where you live or when you face pollution, simple steps such as checking the air quality index, wearing a well-fitting mask and using air purifiers can reduce exposure to harmful pollutants.

An estimated 1 billion people worldwide celebrate Diwali, a holiday of Hindus and Jains with ties to ancient epics such as the Ramayana. Fireworks traditionally set off during the holiday, which starts Sunday, can make polluted air more dangerous.

As Diwali approaches, here are ways to reduce exposure to polluted air.

Fireworks add a sharp burst of pollution to a much bigger problem. Across India, Pakistan and other parts of South Asia, traffic, factories, dust from construction and burning of crop residues and waste foul the air. Weak winds and stagnant winter air allow that pollution to build up.

“Poor air quality is our all-year-round problem in our country,” said Shweta Narayan, a public health expert at the Global Climate and Health Alliance. Narayan said firecrackers add to the problem.

India’s air quality index turns pollution measurements into a health warning. AQI readings of 201–300 mean “poor,” 301–400 “very poor” and 401–500 “severe.” Severe levels can harm even healthy people.

Check pollution levels on government or privately run websites before heading outdoors. Look for data from a nearby monitoring station and the time of its last update. A citywide average can conceal a polluted neighborhood.

The problem is especially bad in Delhi, where fine particle pollution averaged about 19 times the World Health Organization’s annual guideline last year. Air pollution monitors have reached the maximum reading they can display multiple times in recent years.

City authorities have responded with temporary construction, industrial and vehicle restrictions. Public health experts said such measures often fail to address the root causes. The city of more than 20 million people is also implementing a long-term plan to promote use of electric vehicles.

Dr. Arvind Kumar, a chest surgeon at Medanta hospital near Delhi and founder trustee of the Lung Care Foundation, recommends using properly fitted N95 or N99 masks outdoors during periods of heavy pollution. These masks are available at pharmacies, hardware stores and online retailers.

N95 filters are designed to capture at least 95% of airborne particles; N99 filters are made to capture at least 99%. The particle respirator masks do not filter harmful gases.

Cover your nose, mouth and chin. Shape the nose clip and check the seal every time. Facial hair can break that seal. The aim, Kumar said, is to ensure “all the breathing is through the mask and not around the mask.”

Replace disposable masks when dirty, damaged or hard to breathe through. Never put a mask on a child younger than 2. People with heart or lung disease should seek medical advice about mask use.

Loose surgical masks, cloth masks and scarves offer unreliable protection against fine particles.

Kumar said pollution can cause persistent coughing, inflame the airways and trigger asthma-like attacks. He also cited increased risks of pneumonia, heart attacks and strokes, while linking prolonged exposure to impaired lung development in children and lung cancer.

Kumar said people should avoid strenuous exercise outdoors during heavy pollution, including early mornings, when pollution levels can be high.

Using the right air purifiers indoors can help. The devices draw in air to filter out pollutants, then recirculate the cleaner air.

A purifier needs enough capacity to clean the air of the room where it runs. Look for a high-efficiency particulate air, or HEPA, filter. Then check its clean air delivery rate, which is the volume of filtered air it supplies.

Place the purifier where you spend the most time, such as the bedroom. Keep its airflow clear and run it consistently.

HEPA filters trap particles. Substantial activated-carbon filters can remove some gases. No purifier removes every pollutant. Avoid machines that deliberately produce ozone, which irritates the lungs.

Cleaner indoor air reduces exposure, but a purifier cannot eliminate pollution’s health risks, Kumar said.

Kumar said it’s important to avoid incense, mosquito coils and candles. Their particles can linger indoors for hours, especially in poorly ventilated rooms, while fireworks pollution can persist overnight, depending on the weather. When many households set off fireworks, their combined emissions can worsen air quality across neighborhoods and entire cities, exposing people who are not taking part. Electric lights can be another way to celebrate Diwali, avoiding toxic gases and smoke from firecrackers.

“If one wants to celebrate and really enjoy the festival of Diwali, avoid bursting firecrackers,” said Narayan, the public health expert.

India’s health ministry also recommends reducing smoky cooking and using a kitchen exhaust that vents outdoors. Damp-mopping floors and wiping dusty surfaces, instead of dry sweeping, can avoid stirring up particles that worsen air quality.

Personal precautions have limits. Narayan said people who earn their livelihoods outdoors cannot simply stay home. Many families also cannot afford air purifiers.

She called for sustained action on pollution sources and affordable health care for those already suffering. Masks and filters can reduce exposure, but lasting protection requires governments to clean the air.

“It’s our responsibility to hold our governments accountable,” Narayan said. “There’s no other way about it.”

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Sibi Arasu can be followed on X at @sibi123. Reach him at sarasu@ap.org.

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