KUALA LUMPUR: Muhammad Syahir Azali still remembers the fear of watching his nine-year-old daughter struggle to breathe.
Puteri Hannah Amelia had started with a cough and inflamed throat, but within days her condition worsened into chest pain and breathing difficulties.
Syahir rushed her to hospital, where she remained for five days after being diagnosed with a mycoplasma infection and bronchitis that doctors linked to haze exposure.
“At first, she had been coughing for two days, so I took her to a nearby clinic to consult a doctor and get some medication,” the 35-year-old said.
“However, her condition did not improve. By the third day, it had worsened, and she began experiencing breathing difficulties and chest pain.”
The episode was the first time Hannah had been hospitalised because of a haze-related illness. She missed school during her recovery, and doctors advised the family to make sure she wore a face mask even indoors.
For Syahir, the experience stripped the haze of its familiar, almost seasonal quality. What can look like little more than a grey sky or distant smell of smoke can become something far more serious when a child is already vulnerable.
When exercise becomes exposure
Healthy adults can be affected, too, particularly when exercising outdoors.
Running enthusiast Syahirah Atikah, 36, recently took part in a city marathon after checking that the Air Pollutant Index (API) reading remained below 100. She felt confident enough to continue, but the haze thickened as the morning went on.
“After completing my run, I experienced chest tightness and difficulty breathing,” she said. The following day, she took sick leave after developing a headache and severe cold.
Paediatric respiratory physician Dr Noor Zehan Abdul Rahim said prolonged or repeated exposure to haze can inflame the respiratory tract because fine particles such as PM2.5 penetrate deep into the lungs.
Children are particularly vulnerable because their lungs are still developing, while older adults may have less capacity to clear inhaled particles.
Symptoms can include persistent coughing, wheezing, mucus production, chest tightness and breathlessness. For children with existing respiratory conditions such as asthma, repeated exposure can also trigger flare-ups and worsen symptoms.
Exercise brings another problem: the harder people work, the more deeply they breathe.
Tolullah Oni, chair of Global Public Health and Sustainable Urban Development at the University of Cambridge, said runners may inhale greater quantities of polluted air simply because their breathing becomes faster and deeper during exercise.
The route matters, too: running beside busy roads can increase exposure to vehicle pollution, while even small changes in distance from traffic can reduce the amount inhaled. Transboundary haze is harder to escape, however, because it can cover a much wider area.
“Under severe haze conditions, exposure would undoubtedly be worse. It is not something I would recommend for outdoor running,” Oni said.
Knowing when to stay indoors
The health ministry has already reported increases in some haze-related illnesses, including upper respiratory tract infections and conjunctivitis. But for individuals and families, the more immediate question is often how to judge when an ordinary day outside is no longer worth the risk.
Respiratory physician Dr Syed Ajmal Syed Ali advises limiting outdoor exposure when air quality deteriorates, avoiding strenuous exercise, staying hydrated and continuing prescribed medication for existing respiratory conditions.
Anyone who experiences worsening breathlessness, wheezing or chest tightness should seek medical attention rather than wait for the haze to clear.
Weather can bring temporary relief, with rainfall helping reduce pollutants in the atmosphere. But changing winds can also carry smoke from forest and land fires in neighbouring countries back across Malaysia, meaning conditions can shift quickly.
For families like Syahir’s, that uncertainty makes the haze more than an inconvenience. Once you have watched a child fight for breath, checking the air outside becomes less about whether the sky looks hazy - and more about whether it is safe to step out at all.