Haze, Allergic Rhinitis and Sinus Flare-Ups: What to Know

Haze irritates the lining of your nose and sinuses. If you have allergic rhinitis, expect more sneezing, blockage and runny nose, and in some people a sinus infection. For most people, haze irritation settles when the air clears. Symptoms that last, get worse or come with a fever need a doctor.

For causes of haze in Singapore and PM2.5, see our guide to haze and your health.

For protection steps such as masks and air purifiers, see our haze season tips.

How does haze affect your nose and sinuses?

Your nose is the first line of defence. It warms, humidifies and filters the air you breathe. Haze particles irritate its lining, which can cause a runny or blocked nose, sneezing and a scratchy throat. In healthy people, this irritation usually settles on its own (Ministry of Health, Singapore, 2016).

Your sinuses are air-filled spaces that drain into the nose. When the nose lining swells, drainage can slow down and the sinuses feel blocked or pressured.

People who breathe through the mouth, often because of long-term nasal blockage, miss out on the nose’s filtering. Fine particles then reach the throat and lungs more easily.

If you have allergic rhinitis, will haze make it worse?

It can.

Allergic rhinitis is inflammation of the nose lining that is triggered by allergens, and in Singapore a common trigger is the house dust mite. The lining is already hypersensitive, so haze particles can lead to stronger symptoms that flare more often and take longer to settle.

Typical symptoms are sneezing, an itchy, runny or blocked nose, and sometimes itchy, watery eyes.

Evidence on haze itself is limited, but studies of air pollution point the same way:

• A prospective study in China followed people with allergic rhinitis and found that exposure to higher levels of ambient air pollutants was linked to worse symptoms (Sun et al., 2024).
• A study of 225 children aged 6 to 15 with allergic rhinitis in Taichung, Taiwan, found that air pollutants, including PM2.5, were linked to poorer quality-of-life scores in boys who were sensitised to the dust mite Blomia tropicalis. This link was not seen in boys sensitised to other mites (Quek et al., 2019).

When is allergic rhinitis "uncontrolled"?

Allergic rhinitis is considered poorly controlled if it affects 4 days a week. A specialist review is recommended if you do not get better despite medicine from your family physician.

Can haze trigger a sinus infection?

Haze does not directly infect your sinuses. But uncontrolled rhinitis can block sinus drainage, and trapped mucus can lead to congestion, facial pain and infection (sinusitis).

Studies that link PM2.5 to long-lasting sinus inflammation (chronic rhinosinusitis) look at years of exposure, so they do not show that a few weeks of haze causes it.

See a doctor if your sinus symptoms:

• last longer than about 10 days
• get worse after an initial improvement
• come with facial pain or pressure, thick discoloured nasal discharge or a fever

Get urgent care for:

• swelling or redness around the eye
• double vision or reduced vision
• a severe headache or stiff neck
• confusion or a high fever

Which other conditions can haze flare up?

Haze particles do not stop at the nose. They travel down into the airways and settle on the surface of the eye, so several other conditions can flare up. The ones below are the most common, and for asthma and COPD the evidence is strongest. They are also the conditions most easily mistaken for a simple haze reaction, which is why it helps to know their signs.

In addition to allergic rhinitis, these are:

Asthma

Haze can inflame the airways and trigger attacks. Wildfire smoke is linked to asthma flare-ups, emergency visits and admissions (Wilgus & Merchant, 2024). Across eight countries and territories, every 1 µg/m³ rise in wildfire PM2.5 was linked to 0.48% more asthma hospitalisations (Zhang et al., 2025). In Singapore, every 10-unit rise in the 24-hour PSI was linked to 3.1% more asthma admissions (Ministry of Health, Singapore, 2016).

Bronchitis

Irritated airways can swell and produce extra mucus, causing a cough with phlegm, wheeze, chest discomfort and breathlessness. Haze can bring on these bronchitis-type symptoms.

Chronic obstructive pulmonary disease (COPD)

People with COPD are more vulnerable to flare-ups (Wilgus & Merchant, 2024). In the same eight-country analysis, every 1 µg/m³ rise in wildfire PM2.5 was linked to 0.38% more COPD hospitalisations (Zhang et al., 2025).

Conjunctivitis and red, itchy eyes

Haze can irritate the surface of the eye, causing red, itchy, watery eyes. People with dry eyes or allergic conjunctivitis may be more affected. SingHealth lists an allergic reaction to smoke as a cause of sore eyes (SingHealth, n.d.).

Upper respiratory tract infection

Haze irritation can look like a common cold, and haze may make infections more likely. Across eight countries and territories, every 1 µg/m³ rise in wildfire PM2.5 was linked to 0.42% more hospitalisations for acute upper respiratory infection (Zhang et al., 2025). The evidence here is less settled than for asthma and COPD.

Is it haze irritation or an infection?

Irritation from haze tends to ease when you are away from the smoke or when the air clears. An infection is more likely if you have a fever, or if symptoms last or get worse.

How can I manage my nose and sinus symptoms during the haze?

If you already have allergic rhinitis, the aim is to keep it controlled before and during haze:

• Keep using your prescribed nasal steroid spray or antihistamine as directed. If you stopped, ask your doctor about restarting.
• Rinse your nose with saline to flush out irritants and mucus. Use sterile, distilled or previously boiled and cooled water, and clean the device after each use.
• Avoid rubbing itchy eyes, and ask your doctor about eye drops if they are bothersome.
• Keep up measures against house dust mites, your usual trigger.
• See a doctor if symptoms stay uncontrolled. Frequent, severe cases may benefit from review by an ENT specialist.

For protection steps such as staying indoors, masks, air purifiers and air-conditioner filters, see our haze season tips.