FAQs on Haze Health Advisory

IMPACT OF HAZE ON HEALTH

1.     What are the key air pollutants of concern during haze period?

The key air pollutant of concern during the haze period is particulate matter (PM). Short term exposure (i.e. continuous exposure to unhealthy daily average Pollutant Standards Index (PSI) levels over a period of a few days) to these air pollutants can cause respiratory symptoms and aggravate existing heart or lung disease.

Exposure to particulate matter may also cause irritation of the eyes, nose and throat in healthy individuals.

2.     What is the short term effect of the haze on my health?

Among healthy individuals, short term exposure (i.e. continuous exposure to unhealthy daily average PSI levels over a period of a few days) to high levels of haze particles may cause irritation of the eyes, nose, and throat in healthy individuals. Such irritation resolves on its own in most cases.

Haze particles can sometimes affect the heart and lungs, especially in people who already have chronic heart or lung disease e.g. asthma, chronic obstructive pulmonary disease (COPD), or heart failure.

There may be up to one to three days of time between exposure to haze and health effects/ symptoms.

3.     Since Singapore experiences short-term exposure to haze, what local studies have been conducted to assess and quantify the short-term effects?

MOH has conducted studies to assess the short-term effects of air pollution on the health of the general population, using air quality data from 1994-2012.

One study found that an increase of 10µg/m³ daily concentration of PM10 and PM2.5 was associated with a 1.1% increase in hospital admissions for respiratory diseases. Another study on the health effects of previous haze episodes (1994, 1997, 2006 and 2010) showed that a 10-unit increase in 24-hr PSI was associated with 3.1% increase in hospital admissions for asthma.

The estimates obtained from the local studies were within the range of estimates from international studies.

4.     What are the long term effects of the haze?

Singapore is not affected by the haze throughout the year.

Any exposure is short-term in nature (i.e. continuous exposure to unhealthy daily average PSI levels over a period of a few days) and such exposure may vary from year to year.  As international studies are based on long term exposure to air pollution, there is little robust data on the longer-term effects of episodic short-term exposures to haze like the pattern seen in Singapore.

Studies have shown that persons living overseas with continuous exposure over several years to high ambient pollution from fine particles (i.e. particulate matter 2.5 (PM2.5); particles smaller than 2.5 micrometres), may have a higher risk of (i) cardiovascular effects, such as heart attacks, (ii) reduced lung development, as well as (iii) the development of chronic respiratory diseases, such as asthma, in children.

5.     Although Singapore is not affected by haze throughout the year, it may keep recurring. Will we then be studying the long-term effects of short-term exposure to haze?

There is currently no data both locally or internationally, which looks into the long term health impact of short-term, episodic exposure to haze.

Researching this would be highly challenging. Any results would be based on observational studies only, which would not be able to show a definite cause-and-effect relationship. It would be difficult to study the direct long-term health effects due to the episodic exposure to haze, as there could be many other contributing factors to the long-term health outcome we are measuring. For example, it would be difficult to be sure that intermittent exposure to haze twenty years ago caused the chronic obstructive pulmonary disease (COPD) in a person today, since COPD could also have been caused by other factors such as smoking, previous lung infection, or existing lung diseases.

Although there are overseas studies on long-term health impact, these have been based on long-term exposures, which are different from the pattern of exposure here. These studies showed that continuous, long-term exposure to air pollutants over several years may result in lung function abnormalities in children and subsequently, in adulthood. This could lead to greater susceptibility to the effects of ageing, infection and other pollutants, such as tobacco smoke, in adults.

6.     How is the air quality forecasted? Why is the health advisory based on 24-hour PSI forecast?

During haze episodes, the National Environment Agency (NEA) will provide an air quality forecast for the next 24 hours. NEA will look at all relevant factors, including weather conditions, in determining this forward projection.

Health impacts are related to concentrations as well as duration of exposure, in addition to the health status and level of activity of the individual. The health advisory issued in the daily haze situation update is based on 24-hour PSI forecast as scientific and epidemiological studies on the health effects of particulate matter have been based on 24-hour PSI.

Please refer to the MOH health advisory.

7.     Which groups of people are more sensitive to haze? 

In general, children, elderly, and people with chronic lung disease or heart disease are more sensitive to the health effects of haze, and should adopt the preventive measures in the MOH health advisory when air quality is poor.

Individuals are advised to consult their doctor should they develop breathing difficulties. In addition, it is advised that pregnant women reduce exposure to haze for the health of their unborn baby.

8.     What is MOH’s advice to the public?

The public is recommended to adhere to the MOH health advisory. In most cases, it is still safe to carry on with outdoor activities. However, drinking plenty of water may help symptoms such as a dry or itchy throat.

Individuals with existing chronic heart and lung conditions should ensure that your medications are on hand and readily available.

Each individual’s reaction to pollutants may vary, and the amount of physical activity or exertion that can be performed differs according to your health status or physical capacity. Should you encounter symptoms or discomfort, please take additional measures to prevent further exposure.

Although the general advice to the public when the forecasted air quality is good or moderate (PSI≤100) is to maintain normal activities, vulnerable persons, especially those with chronic heart and lung conditions who develop symptoms or feel unwell, should seek medical attention promptly.

USE OF MASKS

9.     Do I need to wear a N95 mask?

N95 masks are not needed for short exposure, like commuting from home to school or work, travel from bus-stop to shopping mall. N95 masks are also not needed in an indoor environment.

A healthy person who has to be outdoors for several hours when the forecasted air quality is in the hazardous range (PSI >300) may reduce exposure by wearing a N95 mask. 

10.    What about vulnerable groups of people? Should they wear masks to protect themselves?

The best form of protection for people with chronic lung or heart disease, elderly, and pregnant women is to avoid or minimise outdoor activity when the forecasted air quality is unhealthy (PSI > 200). If they have to be outdoors for several hours, they may reduce exposure by wearing a N95 mask.

You should take a break from using a N95 mask if you feel uncomfortable. Elderly, pregnant women and people with severe lung or heart problems who have difficulty breathing at rest or on exertion should consult their doctor as to whether they should use the N95 mask.

Women in the second and third trimesters of pregnancy may already have reduced lung volumes or breathing issues. They should stop using a N95 mask if they feel uncomfortable. 

11.    Is the N95 mask an adequate protection against haze? Does it protect against PM2.5?

N95 masks work only if there is a good fit with the face of the wearer. This way, most of the air that the wearer breathes in has to go through the filter and not through the gaps between the mask and the wearer’s face.

Haze can contain fine particles that are 2.5 microns or smaller (PM2.5), and studies have shown that N95 masks do provide good protection against particle pollutants as they are at least 95% efficient against fine particles that are about 0.1 – 0.3 microns. 

12.    What are the effects of wearing a N95 mask?

The use of N95 masks increases effort in breathing. For some people, the use of N95 mask may cause discomfort in breathing, tiredness or headache. This may be due to the mask causing increased resistance to breathing, and a reduction in the volume of air breathed. For most people this is not serious.

Some elderly people, people with lung or heart conditions, and women in the later stages of pregnancy may already have reduced lung volumes or breathing issues.

You should take a break from using a N95 mask if you feel uncomfortable. Elderly, pregnant women and people with severe lung or heart problems who have difficulty breathing at rest or on exertion should consult their doctor as to whether they should use the N95 mask.

Women in the second and third trimesters of pregnancy may already have reduced lung volumes or breathing issues. They should stop using a N95 mask if they feel uncomfortable. 

13.    How do I get a mask? 

Masks are available at major pharmacies and supermarkets. The national stockpile of N95 masks may be released to the major pharmacies and supermarkets if more are needed.

Employers of workers who are required to work outdoors for prolonged period are encouraged to maintain a seven-day stock for immediate use when necessary. Procurement of additional masks can be made through the major pharmacies and supermarkets. 

14.    Are there different types of N95 masks in the market?

There are different brands of N95 masks in the market which have the same functionality. They come in different colours, shapes and sizes. Please also refer to Annex A. 

15.    What are EN-149: 2001 masks? Are they equivalent to the N95 masks? 

EN-149 is one of the European Standard for masks while N95 masks are certified by the US National Institute for Occupational Safety and Health (NIOSH). Both types of masks are designed to reduce wearer’s respiratory exposure to airborne contaminants such as particles, gases or vapours.

The EN-149 masks are classified in three classes depending on the ability to separate air-borne particles according to the FFP (Filtering Face Pieces):

• NIOSH
• the type of approval (e.g. N95)
• the manufacturer’s name

A list of NIOSH certified N95 masks is available on the NIOSH website. Please also see Annex B for some examples.

EN149 is the European Standard for respiratory mask designed to reduce wearer’s respiratory exposure to airborne contaminants such as particles, gases or vapours. Masks are classified in three classes depending on the ability to separate air-borne particles according to the FFP (Filtering Face Pieces). A European standard certified mask will have the following text printed on it:

• the CE mark
• EN 149:2001; the classification of the mask (e.g. FFP2)
• the manufacturer’s name

17.    How does a consumer choose which mask to purchase?

Both the NIOSH-certified N95 masks or the EN-149 masks are designed to reduce wearer’s respiratory exposure to airborne contaminants such as particles, gases or vapours.

Consumers should perform a fit check to ensure a good fit. 

18.    How do I learn to fit my N95 mask?

For best effect, N95 masks need to be fitted properly for each user. To check for proper fit, please check that the available mask is appropriately sized and covers the nose and mouth comfortably without leak.

Please refer to Annex C for a step-by-step guide on how to wear N95 masks properly.

The use of N95 masks to filter out pollutants in the air is not identical to the use of N95 masks for infection control in a healthcare institution during a disease pandemic situation. For use during a haze incident, even if the mask is not perfectly fitted, it can still be useful in filtering out pollutants for those who need to wear it. 

19.    Can I reuse my N95 mask used for protection against Haze?

Yes, the N95 can be reused unless it gets soiled or distorted in shape. There is no absolute duration of use before discarding, but generally should not be reused for more than 5 separate occasions.  

20.    Are surgical masks useful?

Normal surgical masks are not effective in filtering fine particles (i.e. tiny particles that are 2.5 microns or less in width), although they can reduce the discomfort cause by haze by providing a barrier between the wearer’s nose and mouth, and larger irritant particles in the air. 

21.    Are surgical masks the same as N95 masks?

Surgical masks and N95 masks are different and were made for different purposes. Surgical masks were designed to protect the surrounding environment from the user’s own spit or mucous. Healthcare professionals use them (e.g. in an operating theatre) to prevent their own germs from infecting the patient.

N95 masks were designed to protect the wearer from airborne particles. Studies have shown that they are at least 95% efficient against fine particles that are about 0.1 – 0.3 microns, assuming good fit on the wearer’s face. 

22.    Are the AIR+ Smart Masks safe?

The mask has been tested according to European Standard EN 149:2001=A1:2009 to benchmark its quality and performance and is certified to be safe for use in adults. 

23.    What are the findings of the clinical trial on the impact of the AIR+ Smart Mask on children?

The key precaution for children during haze is to minimize prolonged or strenuous outdoor physical exertion when the forecasted air quality is unhealthy (24-hr PSI>100), and avoid outdoor activity when the forecasted air quality is in the hazardous range (24-hr PSI>300). 

There are currently no international certification standards for use of masks in children. Certification standards apply to use in adults only.  

The clinical trial conducted by the manufacturer (i.e. Innosparks Pte Ltd) on the impact of the AIR+ Smart Mask on children aged 7 to 14 years found that the AIR+ Smart Mask, with and without the micro-ventilator, can be used safely in children with no existing heart and lung conditions. To be effective, the mask needs to maintain a well-fitted seal at all times. If the child experiences breathing discomfort while using the mask, it should be removed. 

24.    What level of activity can be conducted when wearing the AIR+ Smart Masks?

Children who wear the mask with or without the micro-ventilators can carry out light physical activity such as brisk walking. Children are not advised to carry out greater levels of physical activity when wearing the mask, even with the micro-ventilator.  

25.    Should children with pre-existing respiratory conditions (e.g. asthma) use the AIR+ Smart Mask?

The key precaution for persons with pre-existing lung and heart disease is to avoid prolonged or strenuous outdoor physical exertion when the forecasted air quality is unhealthy (24-hr PSI>100), and avoid outdoor activity when the forecasted air quality is in the very unhealthy and hazardous range (24-hr PSI>200). Children with chronic heart and lung conditions may respond differently to the mask. Please consult your child’s doctor if there is any doubt or if your child experiences discomfort.

26.    How will the haze impact patients in nursing homes and subsidised wards with natural ventilation?

The healthcare institutions will institute specific measures to manage particulate matter (PM) levels in indoor spaces, taking reference from NEA’s guidelines on indoor air quality. The healthcare institutions will also monitor patients closely, and ensure ample circulation of clean air indoors.

27.    Can face masks used for COVID-19 be used against haze exposure?

During the current COVID-19 situation, the use of a face mask is mandatory when people go outside their homes. This continues to apply should the forecasted air quality be in the Hazardous range (PSI >300);

Normal surgical masks, unlike N95 masks, are not effective in filtering fine particles (i.e. tiny particles that are 2.5 microns or less in width) present in haze; and

In general, a healthy individual who has to be outdoors for several hours may wear a N95 mask instead of a conventional face mask to reduce exposure when the forecasted air quality is in the Hazardous range (PSI >300). N95 masks are not needed in indoor environments, and not needed for short exposure when outdoors, like commuting from home to school or work, travelling from bus-stop to shopping mall.

28.    Can KF94 masks be used to protect against Haze?

Yes, the KF94 and N95 are largely similar, filtering a nearly identical percentage of airborne particles (KF94 94% vs N95 95%). Therefore, KF94 masks can be used to protect against haze as well as N95.

29.    Can KF94 masks be used to protect against Haze?

Yes, N95 masks (or equivalent*) with or without valves may be worn to protect against haze.            

*with similar filtration capability, for example, the KF94 and KN95 masks