Haze is more than a visibility problem. The fine particles suspended in hazy air can enter deep into the lungs, aggravate existing health conditions and cause respiratory symptoms even in otherwise healthy people.
Understanding the risks, and knowing how to protect yourself, is especially important for children, older adults, people with heart or lung conditions, and those who spend long hours outdoors.
How does haze affect the lungs?
One of the main pollutants of concern during haze is PM2.5. These particles measure 2.5 micrometres or less—approximately 30 times smaller than the diameter of a human hair.
Because of their extremely small size, PM2.5 particles can travel deep into the lungs and reach the alveoli, the tiny air sacs where oxygen enters the blood. Some of the smallest particles, or their chemical components, may also enter the circulation.
Exposure may cause:
- Throat irritation and coughing
- Wheezing
- Chest tightness
- Shortness of breath
- Worsening of asthma or other respiratory conditions
- Worsening of cardiovascular disease
The level of risk depends on the concentration of pollutants, how long and how often a person is exposed, and the composition of the haze.
Children, older adults, and people with existing heart or lung disease are particularly vulnerable. Outdoor workers—including food delivery riders, construction workers and others who spend extended periods outside—may receive substantially greater exposure.
Which masks provide protection from haze?
For protection against PM2.5, a well-fitting particulate respirator such as an N95, KN95 or KF94 offers better protection than a surgical mask.
These respirators are designed to filter fine airborne particles, provided that they are:
- Genuine and obtained from a reliable source
- Appropriately certified
- The correct size and shape for the wearer
- Worn properly, with a close fit to the face
A surgical mask may filter some particles, but it does not provide the same level of protection. Its loose fit allows polluted air to enter through gaps around the sides.
Why is fit so important?
Even a high-quality respirator cannot provide its intended protection if it does not fit properly. Air follows the easiest available path. If there are gaps between the respirator and the face, polluted air can bypass the filter.
A respirator should fit closely around the nose, cheeks and chin. Facial hair in the sealing area can interfere with the fit.
Workers who are required to wear respirators should undergo a formal respirator fit test. This is particularly important for people who spend prolonged periods outdoors because of their occupation.
What if wearing a respirator makes breathing difficult?
Respirators increase breathing resistance and may feel uncomfortable. For some people, particularly those with respiratory or cardiovascular conditions, they may make breathing more difficult.
If you cannot breathe comfortably while wearing a respirator, do not simply force yourself to continue using it or switch to an unsuitable form of protection. Seek medical advice, as significant breathing difficulty may be dangerous.
People with health conditions who must wear respiratory protection for work should be assessed by a respiratory physician or occupational health doctor. The doctor can consider the person’s medical condition, work requirements and ability to use a respirator safely. Employers should also consider measures that reduce or avoid outdoor exposure.
There is no single alternative mask that will necessarily be safe and effective for everyone who cannot tolerate a respirator. Medical assessment, proper fit testing and adjustments to work duties may therefore be necessary.
Seek urgent medical attention if you experience severe breathlessness, chest pain, confusion, fainting, or rapidly worsening symptoms.
Avoid outdoor exercise during haze
Wearing a respirator does not make strenuous outdoor exercise safe during haze. Exercise increases breathing rate and effort, causing a person to inhale more air, and potentially more pollutants. Exercising while wearing a respirator also increases the work of breathing.
During periods of poor air quality, postpone outdoor exercise and choose indoor activities in a cleaner environment instead.
Masks are only one part of protection
Respirators can reduce exposure, but they should not be the only precaution. During severe haze:
- Monitor local Air Pollutant Index readings and official health advisories.
- Reduce unnecessary outdoor activities.
- Avoid strenuous outdoor work and exercise where possible.
- Spend more time in cleaner indoor environments.
- Keep doors and windows closed when outdoor air quality is poor, where appropriate.
- Minimise indoor pollution from smoking, open burning, candles and other combustion sources.
- Continue prescribed medication and keep reliever medication readily available if advised by your doctor.
- Seek medical care if respiratory symptoms develop or worsen.
The most effective approach is to reduce exposure wherever possible and use a genuine, well-fitting respirator when outdoor exposure cannot be avoided.
This article is based on an interview with Universiti Malaya occupational health and public health medicine specialist Prof Dr Victor Hoe. The interview was published by The Star on 25 September 2026. The information provided is for public education and does not replace individual medical advice.
You must be logged in to post a comment.