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SINGAPORE – The smell of something burning is often associated with worsening air quality and cross-border haze, but this is not always the case, the National Environment Agency (NEA) said on Tuesday (March 2). ).
He added that such odors could come from a variety of sources, including local and regional fires, and can be more pronounced during certain periods of the day due to weather conditions.
To better understand air quality and make decisions about whether to engage in outdoor activities, individuals should consult the NEA website or the mist microsite.
The agency was responding to inquiries from The Straits Times.
Last Saturday, air quality in northern Singapore reached unhealthy levels. But this was due to the elevated levels of ozone, a type of odorless pollutant.
And earlier this week, a burning smell was reported in many parts of Singapore after north winds brought smoke from a hot spot in Johor. However, despite the persistent odor and hazy conditions, air quality remained in the “moderate” range.
Q: How is air quality measured in Singapore?
TO: The Pollutant Standards Index (PSI) is used as an indicator of air quality in Singapore.
It is calculated on the basis of six pollutants: particulate matter, fine particulate matter (PM2.5), sulfur dioxide, carbon monoxide, ozone, and nitrogen dioxide.
To derive the PSI, the NEA takes the average concentration levels of each of the six key air pollutants and converts each of them into a formula-based pollutant subscript.
Averages are taken over a 24-hour period for PM2.5, particulate matter, and sulfur dioxide, an eight-hour period for ozone and carbon monoxide, and a one-hour period for nitrogen dioxide. The highest subscript will be the PSI value for that hour, the NEA said.
During foggy periods caused by wildfires in the region, the dominant pollutant is PM2.5.
The PSI is the only air quality measure in Singapore linked to a health advisory. Air quality is considered unhealthy when the PSI is in the range of 101 to 200.
During these periods, healthy people are urged to reduce prolonged or strenuous physical exertion in the open air, while vulnerable groups, including pregnant women, children and the elderly, are advised to minimize such exertion.
When air quality is “moderate”, with PSI readings between 51 and 100, normal activity can continue for all groups.
Q: Should vulnerable people go outside when a burning smell is detected?
TO: There is no good correlation between a burning smell in the air and concentration levels of PSI or PM2.5, the NEA said.
While these odors can sometimes be accompanied by slightly higher PSI or PM2.5 concentration levels, this may not always be the case.
To help people decide whether to continue outdoor activities, such as jogging, the NEA introduced four-band one-hour PM2.5 readings last year.
Band 1 PM2.5 readings, referred to PM2.5 concentrations between 0 and 55 micrograms per cubic meter of air, are normal and all activities can be performed.
When this reading reaches Band 2, PM2.5 concentrations are between 56 and 150 micrograms per cubic meter of air, a concentration considered high. People are urged to cut down on strenuous outdoor activities for the next hour.
On Tuesday, the hourly concentration of PM2.5 entered Band 2 (High) between 6 a.m. M. And 7 a. M. In eastern Singapore before returning to Band 1 (Normal) starting at 8am. M. From that day. However, the overall PSI remained in the moderate range.
Q: What are some possible causes of burning smell and hazy landscapes?
TO: Ongoing dry conditions due to the current phase of the northeast monsoon season are leading to lower rainfall and warm temperatures.
These conditions are conducive to the development of land and forest fires in neighboring countries, as well as local vegetation fires, the NEA said.
Since the second week of February this year, the Singapore Civil Defense Force (SCDF) has responded to some 30 cases of local vegetation fires.
Most involved small pockets of vegetation around Singapore. The largest fire, spanning about the size of a football field, occurred on February 23 along Tembusu Crescent on Jurong Island, the SCDF said.
The NEA said that depending on the direction of the prevailing winds, smoke haze from fires in the region can be blown into Singapore, resulting in an occasional burning smell, light haze and reduced visibility.
Local vegetation fires can also have similar effects, the agency added.
The smell of burning tends to be accentuated at night and early in the morning when milder winds cause a build-up of airborne particles.
But during the day, the winds get stronger and the sunlight that warms the ground causes the air to move up and down, helping to disperse the particles.
Q: Will the fog return soon?
TO: Air quality expert Dr. Erik Velasco noted that in recent days, the number of hot spots in Riau and Sumatra in Indonesia and the southern provinces of Malaysia has increased somewhat due to the current dry conditions.
“We’re in the tail of the northeast monsoon, so the columns from the Malaysian bushfires can set off that burning smell,” said Dr. Velasco.
“If dry conditions continue, we could expect foggy events, but fortunately, rain is forecast for this month.”
But before the rain arrives, there could be a slight haze in the following days, similar to the slight haze seen in recent days, but Dr. Velasco does not anticipate serious episodes.
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