KEY MESSAGE
When haze levels are unhealthy, reducing exposure to polluted air is the first priority. If a mask is needed, a properly fitted N95 respirator offers better protection against fine particulate matter than a conventional surgical mask.

1. Understanding PSI and PM2.5: Why Should We Be Concerned?

PSI and PM2.5 measure different aspects of air pollution.

• PSI (Pollutant Standards Index) is an index used to communicate overall air quality and associated health concerns. Singapore uses the 24-hour PSI forecast to help people plan their activities.
• PM2.5 refers to fine particulate matter measuring 2.5 micrometres or less in diameter. These tiny particles can penetrate deep into the lungs, and some may enter the bloodstream.

During haze episodes, PM2.5 is particularly important because fine particles can remain suspended in the air and travel considerable distances.

Air quality varies by location and time. Check the latest readings rather than assuming that conditions are the same across Singapore or the wider region. For immediate outdoor activity decisions, Singapore’s NEA advises checking the latest one-hour PM2.5 readings. The 24-hour PSI forecast is useful for planning activities ahead.

Editorial note: Verify and update any dated PSI figures against the latest official NEA advisory immediately before publication.

2. N95 vs Surgical Masks: Which Is More Effective Against Haze?

N95 respirators: Better protection against fine haze particles

An N95 respirator is designed to filter at least 95% of specified airborne test particles under standard testing conditions. When correctly fitted, it can substantially reduce exposure to fine particulate matter, including PM2.5.

Other recognised particulate respirator standards include KN95, FFP2 and KF94, although their certification requirements and fit characteristics differ.

An N95 respirator must fit snugly against the face. Gaps around the nose, cheeks or chin can allow polluted air to bypass the filter.

N95 respirators may be useful when people must spend extended periods outdoors during severe haze conditions. However, they can increase breathing effort and cause discomfort, particularly in people with certain medical conditions.

Surgical masks: Useful for some purposes, but limited against PM2.5

Surgical masks are designed primarily to provide a barrier against larger droplets and to reduce the spread of respiratory secretions from the wearer.

They may offer some protection against larger airborne irritant particles, but their loose fit and design mean they do not provide reliable protection against fine haze particles such as PM2.5.

A surgical mask should not be considered an equivalent substitute for a properly fitted N95 respirator when protection against fine haze particles is needed.

Source: Consult current Singapore Ministry of Health, NEA and Health Sciences Authority guidance for local recommendations.

3. When Should You Consider Wearing an N95 Mask?

Wearing an N95 mask is not automatically necessary every time the sky looks hazy. Consider air quality, duration of outdoor exposure, physical activity and individual health status.

• Healthy individuals: When the forecast PSI is in the Hazardous range (above 300), consider an N95 respirator if you must remain outdoors for several hours.
• Older adults, pregnant women and people with chronic heart or lung conditions: When the forecast PSI is in the Very Unhealthy range (above 200), an N95 respirator may help reduce exposure if prolonged outdoor activity is unavoidable.
• People with asthma or other chronic respiratory conditions: Follow the relevant health advisory, minimise exposure and seek medical advice when needed.
• Short outdoor journeys: An N95 is generally not required for brief exposure, such as travelling between home and a bus stop. Follow current advisories and take extra precautions when PM2.5 readings are elevated.

These are general Singapore recommendations, not universal thresholds for every country. Follow the latest local health advisories wherever you live.

An N95 does not make unnecessary outdoor exercise or prolonged outdoor work safe during severe haze. Reducing exposure remains the priority.

4. How to Wear an N95 Respirator Correctly

1. Choose an appropriate respirator. Purchase a genuine, properly certified product from a reputable supplier. Check the manufacturer’s instructions and expiry information.
2. Inspect the respirator. Do not use one that is damaged, dirty, damp, distorted or has deteriorated straps.
3. Position it correctly. Cover your nose and mouth completely, position it according to the manufacturer’s instructions and secure the straps properly.
4. Adjust the nosepiece. Mould the nosepiece gently around the bridge of your nose to minimise gaps.
5. Check the seal. Follow the manufacturer’s user seal-check instructions. If air leaks around the edges, readjust the respirator. Facial hair in the sealing area can interfere with a proper fit.
6. Monitor your comfort. An N95 can increase breathing effort. If you experience discomfort, stop the activity and move to cleaner air. Seek individual medical advice if you have significant heart or lung problems, are elderly, or are pregnant and unsure whether an N95 is appropriate.

N95 respirators should not be shared. Reuse during haze should follow the manufacturer’s instructions. Replace the respirator if it is damaged, dirty, damp or unable to maintain a good fit.

5. Protecting Children, Older Adults and Other Vulnerable Groups

Haze does not affect everyone equally. Children, older adults, pregnant women and people with chronic heart or lung conditions may be more vulnerable to its effects.

For these groups, the best protection is often to reduce exposure rather than rely on a mask alone.

• Reduce or avoid outdoor activities according to the latest local health advisory.
• Postpone outdoor sports, strenuous exercise and unnecessary trips when air quality deteriorates.
• Keep windows and doors closed when outdoor air is polluted, where appropriate.
• Use a suitable air purifier with an effective particle filter, if available.
• Monitor anyone with asthma or other respiratory conditions for worsening symptoms and follow their prescribed treatment plan.
• Seek medical advice if symptoms persist or worsen.

Children require special consideration because an adult-sized N95 may not fit their faces properly. Do not assume that an adult respirator will protect a child effectively. Consult local health guidance and a healthcare professional about age-appropriate protection.

People with severe heart or lung disease, or those who experience difficulty breathing at rest or during activity, should consult their doctor before using an N95 respirator. Those in the later stages of pregnancy should also seek individual advice before prolonged use.

6. What Should Workplaces, Caregivers and Healthcare Facilities Do?

At STS Academia, we believe infection prevention and health protection depend on practical knowledge, sound decisions and consistent action.

For workplaces

• Monitor official air quality updates and communicate relevant advisories to staff.
• Reduce prolonged or strenuous outdoor work when air quality is unhealthy.
• Reschedule outdoor activities where possible.
• Assess the need for suitable respiratory protection for staff whose duties require extended outdoor exposure.
• Ensure workers understand how to use any provided respirators correctly.

For caregivers and eldercare facilities

• Replace outdoor activities with indoor alternatives when appropriate.
• Pay particular attention to residents with asthma, chronic lung disease or heart disease.
• Maintain a comfortable indoor environment and use suitable air filtration where available.
• Observe residents for coughing, wheezing, breathlessness or other signs of deterioration.
• Escalate concerning symptoms promptly and follow the facility’s clinical protocols.

For healthcare and community care providers

• Integrate haze preparedness into existing health and safety plans.
• Communicate clearly with staff, residents, patients and family members.
• Review local advisories and ensure that protective measures are appropriate to the setting and the individual’s risk.

These precautions complement, rather than replace, established infection prevention practices.

7. Beyond Masks: Five Ways to Reduce Haze Exposure

• Check official air quality readings. In Singapore, use NEA’s myENV app or the official haze website before planning outdoor activities.
• Reduce outdoor exertion. Move exercise indoors and avoid unnecessary outdoor activity when the haze is severe.
• Improve indoor air quality. Keep windows closed during polluted periods where appropriate, and use an air purifier with an effective particle filter if available.
• Keep your indoor environment comfortable. Maintain suitable ventilation and cooling without unnecessarily drawing polluted outdoor air inside.
• Know when to seek medical attention. Get medical help for worsening breathing difficulties, chest pain or other concerning symptoms. Seek emergency assistance for severe breathing difficulty or significant chest pain.

A mask does not filter every air pollutant. N95 respirators protect against particles, not all gases or vapours that may be present in smoke.

Conclusion: Make Informed Choices, Breathe More Safely

When haze affects Singapore and Southeast Asia, knowing the difference between an N95 respirator and a surgical mask can help you make better decisions.

An N95 respirator generally offers better protection against PM2.5 when correctly fitted. A surgical mask, although useful for certain purposes, is not a reliable substitute for fine-particle protection.

Nevertheless, no mask should create a false sense of security. Monitoring air quality, reducing outdoor exposure, protecting vulnerable individuals and maintaining good indoor air quality remain essential.

At STS Academia, we believe that knowledge empowers people to take meaningful action. By understanding haze risks and applying practical health protection measures, we can help protect ourselves, our families, our workplaces and the communities we serve.

Stay informed. Reduce exposure. Protect your health.

Photo Credit: British Chambers of Commerce, Singapore

Authoritative Resources

• Singapore Ministry of Health — Haze health advisories: https://www.moh.gov.sg/others/haze/
• National Environment Agency — Haze updates and air quality information: https://www.nea.gov.sg/

Sim Tianseng

STS is the principal trainer and founder of STS Academia, specializing in healthcare training in Infection Control, Quality, and Patient Safety. With over a decade of experience as the Chief Infection Control Officer at a leading private hospital group in Singapore and 10 years as an Adjunct Lecturer for Flinders University’s Master of Health Administration programme, He brings deep practical expertise to every course.He is committed to helping everyone, including healthcare professionals, build strong, evidence-based competencies they can apply immediately in their work environment.