As millions of people across South Asia, particularly in northern India, prepare to celebrate Diwali, concerns are growing over worsening air pollution as the festival coincides with the onset of hazardous winter air conditions.
Winter also brings severe smog to parts of Pakistan and China, where warmer air above colder layers traps pollutants close to the ground. In eastern Europe, coal and wood burning for household heating further contribute to seasonal pollution. Meanwhile, countries in the Western Hemisphere face their own air quality challenges as summer wildfires spread smoke across large areas of the United States and Canada.
Experts say people can reduce their exposure to harmful pollutants, regardless of where they live, by taking simple precautions such as monitoring air quality levels, wearing properly fitted masks and using indoor air purifiers.
An estimated one billion people worldwide celebrate Diwali, a festival observed by Hindus and Jains and rooted in ancient epics such as the Ramayana. However, the traditional use of fireworks during the festival, which begins Sunday, can further worsen already polluted air and increase health risks.
As the festival approaches, here are some practical ways to protect yourself from polluted air.
Check air quality before going outdoors
Fireworks contribute an additional surge of pollution to an already serious air quality problem. Across India, Pakistan and other parts of South Asia, vehicle emissions, industrial activities, construction dust, crop-residue burning and waste disposal are major sources of air pollution. Weak winds and stagnant winter conditions allow pollutants to accumulate near the ground.
"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, adding that firecrackers make the situation worse.
India uses the Air Quality Index (AQI) to translate pollution measurements into health warnings. An AQI reading of 201–300 indicates "poor" air quality, 301–400 means "very poor," while readings between 401 and 500 are classified as "severe." At severe levels, pollution can affect even healthy individuals.
Experts recommend checking pollution levels through government or private monitoring websites before going outside. People should look for readings from nearby monitoring stations and check when the information was last updated, as citywide averages may not reflect conditions in individual neighbourhoods.
The situation is particularly alarming in Delhi, where average fine particulate pollution last year was around 19 times higher than the World Health Organization's annual guideline. Air quality monitoring stations have also repeatedly recorded readings beyond their maximum display limits in recent years.
Authorities have introduced temporary restrictions on construction activities, industrial operations and vehicles to tackle the problem. However, public health experts say such measures often fail to address the underlying causes of pollution. The city, home to more than 20 million people, is also pursuing a long-term strategy to encourage the use of electric vehicles.
Ensure your mask fits properly
Dr Arvind Kumar, a chest surgeon at Medanta Hospital near Delhi and founding trustee of the Lung Care Foundation, recommends wearing properly fitted N95 or N99 masks outdoors when pollution levels are high. These masks are available at pharmacies, hardware stores and online outlets.
N95 masks are designed to filter at least 95 per cent of airborne particles, while N99 masks can filter at least 99 per cent. However, these respirators do not protect against harmful gases.
For effective protection, a mask should cover the nose, mouth and chin. Users should adjust the nose clip and check the seal every time they wear it. Facial hair can interfere with a proper seal.
The objective, Kumar said, is to ensure that "all the breathing is through the mask and not around the mask."
Disposable masks should be replaced when they become dirty, damaged or difficult to breathe through. Masks should never be placed on children under two years of age. People suffering from heart or lung diseases should consult a doctor before using them.
Loose surgical masks, cloth masks and scarves do not provide reliable protection against fine particulate pollution.
Kumar warned that exposure to polluted air can cause persistent coughing, inflammation of the airways and asthma-like attacks. He also pointed to increased risks of pneumonia, heart attacks and strokes, while prolonged exposure can affect lung development in children and increase the risk of lung cancer.
He advised people to avoid strenuous outdoor activities during periods of heavy pollution, particularly in the early morning when pollutant concentrations can also be high.
Choose an air purifier suitable for your room
Using an appropriate air purifier indoors can help reduce exposure to harmful pollutants. These devices draw in surrounding air, filter out contaminants and circulate cleaner air back into the room.
However, the purifier must have sufficient capacity to clean the space where it is being used. Experts recommend choosing a device equipped with a high-efficiency particulate air (HEPA) filter and checking its Clean Air Delivery Rate (CADR), which measures the volume of filtered air supplied by the machine.
The purifier should be placed in areas where people spend most of their time, particularly bedrooms. Its airflow should remain unobstructed, and the device should be operated consistently.
HEPA filters capture airborne particles, while sufficiently large activated-carbon filters can help remove certain gases. However, no air purifier can eliminate every type of pollutant.
People should also avoid devices that intentionally generate ozone, as the gas can irritate the lungs.
Kumar said cleaner indoor air can reduce exposure to pollutants, but air purifiers cannot completely eliminate the health risks associated with pollution.
Celebrate Diwali with less smoke
Kumar advised people to avoid burning incense sticks, mosquito coils and candles, as these can release particles that remain indoors for hours, particularly in poorly ventilated spaces.
Pollution from fireworks can also linger overnight, depending on weather conditions. When large numbers of households set off firecrackers simultaneously, the combined emissions can significantly worsen air quality across neighbourhoods and entire cities, affecting even those who do not participate in the celebrations.
Using electric lights is a safer alternative for celebrating Diwali, as they do not produce the smoke and toxic gases associated with firecrackers.
"If one wants to celebrate and really enjoy the festival of Diwali, avoid bursting firecrackers," said Narayan.
India's Health Ministry also recommends limiting smoke from cooking and using kitchen exhaust systems that release fumes outdoors. Damp-mopping floors and wiping dusty surfaces instead of dry sweeping can help prevent dust particles from becoming airborne and further worsening indoor air quality.
Personal precautions are not enough
Experts caution that individual precautions have limitations. People who depend on outdoor work for their livelihoods cannot simply remain indoors to avoid pollution. Similarly, many low-income families cannot afford air purifiers.
Narayan stressed the need for sustained government action to tackle major sources of pollution and ensure affordable healthcare for people already suffering from pollution-related illnesses.
While masks and air filters can help reduce exposure, she said lasting protection depends on governments taking effective measures to improve air quality.
"It's our responsibility to hold our governments accountable," Narayan said. "There's no other way about it."
