ct of Haze on health
Find out what are the key air pollutants of
concern, short and long term health effects, as well as advice on activity
level.
What are the key air pollutants of concern?
The key air pollutants of concern include particulate
matter (PM), sulphur dioxide, ozone, nitrogen dioxide and carbon monoxide.
Short-term exposure (i.e. continuous exposure to unhealthy daily average 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 and sulphur dioxide may also cause irritation of the eyes,
nose and throat in healthy individuals.
In Singapore, the main air pollutant in the event
of haze is particulate matter (PM). Singapore experiences haze from time
to time, usually caused by forest fires in the region. It can be made worse by
dry seasons, changes in wind direction, and when rainfall is low.
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 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 1-3 days of time between
exposure to haze and health effects/ symptoms.
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 short-term exposure 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.
What is the revised Pollutant Standard Index? How
is it different from PSI reporting last year?
The new, integrated air quality reporting index
incorporates PM2.5 in addition to sulphur dioxide (SO2), particulate matter
(PM10), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone. Previously,
health advisories issued by the Government were based on both 24-hour PSI and
24-hour PM2.5, whichever was worse. Under the new air quality reporting system,
the health advisory will be based on the new 24-hour PSI as it now directly
takes into account PM2.5.
Why is the health advisory based on 24-hour PSI,
rather than the 3-hour PSI? Why does Singapore calculate the Particulate Matter
(PM) in air pollution based on the 24-hour measurement? Why not use sub-daily
measurement?
The health impact of exposure to particulate matter
in the air depends on the concentration and duration of the exposure, as well
as the health status and level of activity of the individual. The health
advisory is based on the 24-hour PSI (incorporating 24-hour PM2.5
concentration), as most scientific studies on the health effects of short-term
exposure to PM use 24-hour averages, and have demonstrated good links with
24-hour PM averages. The use of 24-hour averages for PM is also consistent with
international guidelines, such as the US Environmental Protection Agency’s
(EPA) National Ambient Air Quality Standards and the World Health
Organization’s Air Quality Guidelines. Fewer studies have investigated shorter
(sub-daily) exposure timeframes. In fact, a US EPA study in 2011 concluded that
there was insufficient basis to establish a national standard with a
shorter-than-24 hour averaging time. MOH will continue to monitor research in
this area.
Which groups of people are more sensitive to
haze?
In general, children, elderly, and people with
chronic lung disease, 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.
What is MOH’s advice to the public?
The public is recommended to adhere to the MOH haze
health advisory. In most cases, it is still safe to carry on with outdoor
activities. However, do drink plenty of water to stay well hydrated.
Individuals with existing chronic heart and lung conditions should ensure that
your medications are on hand and readily available.
Is the health advisory applicable to everyone?
While
the health advisory provides generic precautionary advice, individual
reactions to pollutants may vary. For instance, some vulnerable people, such as
those with heart and lung conditions, may experience increased symptoms at PSI
levels below 100. Such individuals are advised to be cautious and seek
appropriate medical attention as needed.
How will the haze impact patients in nursing homes and
subsidised wards with natural ventilation?
These
patients are indoors and sedentary. The healthcare institutions, such as
hospitals and nursing homes, will monitor patients closely, and ensure ample
circulation of clean air indoors.
Where can I get more information on haze?
Please
refer to the following websites:
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