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Learn when is it best to wear and N95 mask and how to understand PSI readings when it comes to haze
Is the haze back again? Let’s take precautions. Haze is an atmospheric condition where particles, smoke, dust and moisture suspended in the air, obscuring visibility. Slight haze usually disperses when the winds pick up strength. However, at times, it can linger for days or months. In Singapore, we may experience haze, particularly during the Southwest Monsoon Season (June - September).
Related: How to Buy a Mask That Fits
You are encouraged to use published PSI readings to plan your activities during hazy conditions. Reducing outdoor activities and physical exertion against escalating PSI values can help limit the ill effects from haze exposure.
The National Environment Agency (NEA) publishes two types of readings:
Use this to...
1 Hour PM 2.5 readings
Make decisions on immediate activities, such as going for an outdoor run.
The 1-hour PM2.5 concentrations reflect the PM2.5 levels averaged over one hour and can give you an indication of the current air quality.
24-hour PSI forecast
Plan for tomorrow’s activity
The existing scientific evidence supports the use of our health advisory for future planning.
The 3-hour PSI reading was phased out with effect from 7 Dec 2016
Plan your day in accordance to these activity guidelines:
Elderly, Pregnant Women & Children
Persons with Chronic Lung or Heart Disease
0 - 50(Good)
51 - 100(Moderate)
101 - 200(Unhealthy)
Reduce prolonged or strenuous outdoor physical exertion
Minimise prolonged or strenuous outdoor physical exertion
Avoid prolonged or strenuous outdoor physical exertion
201 - 300(Very Unhealthy)
Minimise outdoor activity
Avoid outdoor activity
Related: When a Mask is a Must
Do adhere to the MOH haze 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.
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. Individuals with existing chronic heart and lung conditions should ensure that your medications are on hand and readily available.
Practical tips to reduce indoor exposure to haze particles at home during a haze episode include:
When you have to be outdoors for several hours, an N95 mask can help filter out haze particles, including PM2.5 particles. Here’s a guide:
Wear an N95 mask when...
Have chronic lung or heart disease,
PSI > 200
Are elderly or pregnant,
Both the NIOSH-certified N95 masks and the EN-149 masks are designed to reduce a wearer’s respiratory exposure to airborne contaminants such as particles, gases or vapours.
Do note that 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.
Follow these tips when buying and using an N95 mask:
You can get live updates on PSI readings on:
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This article was last reviewed on
Tuesday, December 21, 2021
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