From 27 September to 3 October, the Communicable Diseases Agency reported that 44 % of respiratory samples tested positive for influenza, the highest weekly rate since the agency began tracking data in February 2024.

The surge comes as haze from regional fires has pushed PM2.5 levels into the unhealthy range. These tiny particles can slip past the nose’s natural filters and reach deep into the lungs, where they trigger inflammation.

A six‑year study by Duke‑NUS Medical School and Singapore General Hospital found that for every 10‑point rise in PM2.5, emergency‑department visits for respiratory problems increase by about 3 %. The effect may become visible a couple of days after the air‑quality spike.

Doctors warn that poor air quality can worsen existing breathing problems, especially for older adults, young children, pregnant women and anyone with chronic lung or heart disease. However, the Communicable Diseases Agency says there is currently no strong evidence that haze makes influenza itself more severe.

Health authorities recommend that people in vulnerable groups keep their flu shots up to date, avoid staying outdoors when air quality is poor, use prescribed asthma preventer inhalers, stay home if they feel sick, wear a mask and seek medical help if symptoms get worse.