PSI is RIGGED!!!!!!!
- Thread starter dash
- Start date
Re: PSI is RIGGED!!!!!!!
I m personally disappointed with the reaction from the government agencies in this crisis. I think they need to start being proactive.
MOH should have reacted faster to the n95 situation by either distributing them faster to retail agencies or distributing thru the RC etc.They shd have preempted the shortage of N95 mask at the endpoint.
I feel that the private sector could do more as well.
I m personally disappointed with the reaction from the government agencies in this crisis. I think they need to start being proactive.
MOH should have reacted faster to the n95 situation by either distributing them faster to retail agencies or distributing thru the RC etc.They shd have preempted the shortage of N95 mask at the endpoint.
I feel that the private sector could do more as well.
jonleeck
Well-Known Member
Re: PSI is RIGGED!!!!!!!
I was at KK yesterday to get n95 masks for my boys!!!...................
View attachment 51672
IS KK HOSPITAL!.........
I was at KK yesterday to get n95 masks for my boys!!!...................
View attachment 51672
IS KK HOSPITAL!.........
vegadonovan
Well-Known Member
Re: PSI is RIGGED!!!!!!!
Why is everything the government's fault ? Is there no one/thing else to blame?
when I see people reselling masks to make some quick bucks? where did they get it from? a simple case of hogging and profiting. These people will blame you for not fast hand fast leg in this their defense.
Our fellow citizens, friends and what not, have a part in this shortage of masks. Sigh....
naan1974;1007017 said:
Why is everything the government's fault ? Is there no one/thing else to blame?
when I see people reselling masks to make some quick bucks? where did they get it from? a simple case of hogging and profiting. These people will blame you for not fast hand fast leg in this their defense.
Our fellow citizens, friends and what not, have a part in this shortage of masks. Sigh....
vegadonovan
Well-Known Member
Re: PSI is RIGGED!!!!!!!
and nowadays I see rumors about cancer inducing nonsense and toxic rain..... sigh....
and nowadays I see rumors about cancer inducing nonsense and toxic rain..... sigh....
rattyunicorn
Well-Known Member
Re: PSI is RIGGED!!!!!!!
Psst... preorder lai.... give u discount.... $40/kitty. *wink wink*
Hahaha jk.
I see many people unable to sell then and one seller even include free ronald kitty... orbeegoot kind. And then there are the lucky ones whom managed to sell at >30 bux....
seanskye;1007036 said:
Psst... preorder lai.... give u discount.... $40/kitty. *wink wink*
Hahaha jk.
I see many people unable to sell then and one seller even include free ronald kitty... orbeegoot kind. And then there are the lucky ones whom managed to sell at >30 bux....
wobbles
Well-Known Member
Re: PSI is RIGGED!!!!!!!
I agree. Let's not heap blame on the government for everything - especially for things beyond their control, like the haze. The response is somewhat uncoordinated & lacking (and this after they've just given themselves a big fat pat on the back for the decade post SARS - hubris, sheer hubris), and while I DISAGREE with the approach (WTF, subsidizing clinic visits - there are already Polyclinics for that purpose - money is better spent subsidizing the PREVENTION: ie, MASKS availability & releasing the 9 million masks they've got stockpiled), I cannot disagree with their intention (ie. to help).
If anything at all, we have to accept that, with climate change and economic/financial considerations trumping ecological/ethical concerns, this may be a permanent feature in our immediate future. My catchphrase again: SUCK IT IN BOYS, and take it up where the sun don't shine.
vegadonovan;1007034 said:
I agree. Let's not heap blame on the government for everything - especially for things beyond their control, like the haze. The response is somewhat uncoordinated & lacking (and this after they've just given themselves a big fat pat on the back for the decade post SARS - hubris, sheer hubris), and while I DISAGREE with the approach (WTF, subsidizing clinic visits - there are already Polyclinics for that purpose - money is better spent subsidizing the PREVENTION: ie, MASKS availability & releasing the 9 million masks they've got stockpiled), I cannot disagree with their intention (ie. to help).
If anything at all, we have to accept that, with climate change and economic/financial considerations trumping ecological/ethical concerns, this may be a permanent feature in our immediate future. My catchphrase again: SUCK IT IN BOYS, and take it up where the sun don't shine.
Re: PSI is RIGGED!!!!!!!
since the SARS incident Moh has been stockpiling the n95 mask for emergencies. They could have used the SAF to distribute to the RC or cc to sell in controlled numbers to ppl. Instead I believe they were trying to liase w retail pharmacies to distribute their stock to ppl. The bottomline is we need the agencies involved to react fast.
I appreciate why u guys are saying the all the demands made by the ppl are not reasonsble. But I still feel the reaction is just too slow...our crisis mgt is poor look at the mrt breakdowns etc.. We need to start looking the real issues.. Yes there fires burning etc but these are beyond our control.. What was crucial is safeguarding the health of ppl. We shd hv reacted fast by stopping all outdoor activities for school.. Ensured the n95 is distributed to everyone...there are still workers who painting across my house... MOM shd have issued directives to companies earlier.. Reaction is too slow and muted, so ppl are feeling on the ground a sense of neglect.
since the SARS incident Moh has been stockpiling the n95 mask for emergencies. They could have used the SAF to distribute to the RC or cc to sell in controlled numbers to ppl. Instead I believe they were trying to liase w retail pharmacies to distribute their stock to ppl. The bottomline is we need the agencies involved to react fast.
I appreciate why u guys are saying the all the demands made by the ppl are not reasonsble. But I still feel the reaction is just too slow...our crisis mgt is poor look at the mrt breakdowns etc.. We need to start looking the real issues.. Yes there fires burning etc but these are beyond our control.. What was crucial is safeguarding the health of ppl. We shd hv reacted fast by stopping all outdoor activities for school.. Ensured the n95 is distributed to everyone...there are still workers who painting across my house... MOM shd have issued directives to companies earlier.. Reaction is too slow and muted, so ppl are feeling on the ground a sense of neglect.
Re: PSI is RIGGED!!!!!!!
Singaporeans are good at another thing apart from complaining....adapting.
After we are done with the complaining, we adapt n soon everything becomes a way of life...or as many say "complain no use, just bear with it lor..."
Re: transport fare hikes, petrol and PUB price increase, building old folks home, childcare centre within HDB estates, workers dorm in landed property areas, demolishing heritage-able buildings/areas for MRT or condos etc etc...the list goes on.
Haze will be same. Soon N95 masks will be available everywhere. Soon everything will be in place. Haze continues...Singaporeans get used to it and soon we will have innovative stuffs for sale...perhaps aircon masks or simi Haze Sale.
Our govt knows this. This is the true Singapore Spirit. Adaptability. Nothing else
Singaporeans are good at another thing apart from complaining....adapting.
After we are done with the complaining, we adapt n soon everything becomes a way of life...or as many say "complain no use, just bear with it lor..."
Re: transport fare hikes, petrol and PUB price increase, building old folks home, childcare centre within HDB estates, workers dorm in landed property areas, demolishing heritage-able buildings/areas for MRT or condos etc etc...the list goes on.
Haze will be same. Soon N95 masks will be available everywhere. Soon everything will be in place. Haze continues...Singaporeans get used to it and soon we will have innovative stuffs for sale...perhaps aircon masks or simi Haze Sale.
Our govt knows this. This is the true Singapore Spirit. Adaptability. Nothing else
Re: PSI is RIGGED!!!!!!!
I'm laughing as I'm reading this. Singaporeans really are good at complaining and shifting blame. Take my hats off to those who bothered to take precautions than sit and wait for garmen
I'm laughing as I'm reading this. Singaporeans really are good at complaining and shifting blame. Take my hats off to those who bothered to take precautions than sit and wait for garmen
dash
Well-Known Member
Re: PSI is RIGGED!!!!!!!
A link circulating around...
dunno if its a repost...
here it is
NEA
Singapore’s 3-hourly Pollutant Standards Index (PSI) smashed the previous record of 371 set on Thursday (20 Jun) to hit a new high of 401 yesterday (21 Jun) at 12pm.
On Wednesday, the record was 321, set at 10pm. On 3 consecutive days, the PSI set 3 records which means the haze is not only the worst in Singapore’s history, it is getting worse by the day!
To add insult to injury, the National Environment Agency (NEA) in charge of measuring the amount of pollutants in the air appears to be ’smoking’ (pun intended; Singlish for bluffing, deceiving, misleading) Singaporeans.
Using PM10 instead of PM2.5 to calculate PSI
NEA currently bases its “PSI readings” on PM10 only. As it says on its website, “The 3hr PSI readings are calculated based on PM10 concentrations only” (‘NEA’s PSI webpage‘).
What is PM10? Airborne pollutants come in big sizes and small. The big particles are between 2.5 and 10 micrometres in size i.e. 25 to 100 times thinner than a human hair. These particles are called PM10 (pronounced “P M ten”) which stands for Particulate Matter up to 10 micrometres.
Particulate matter – also known as atmospheric particulate matter or simply particulates – are tiny pieces of solid or liquid matter associated with the earth’s atmosphere.
The symbol for micrometre is µm (a symbol found on NEA’s website). 1 micrometre or 1 micron is one-millionth of a metre.
PM10 is also called “respirable suspended particle” or RSP since RSP are particles with a diameter of up to 10 µm.
What is PM2.5? You guessed it, PM2.5 (pronounced “P M two point five”) as in Particulate Matter up to 2.5 µm in size are the relatively small airborne pollutants.
PM2.5 is also known as fine particles since fine particles have a diameter of 2.5 µm or less.
Difference between PM10 and PM2.5
Fine particles i.e. PM2.5 are lighter and stay in the air longer and travel further than PM10. PM10 can stay in the air for minutes or hours while PM2.5 can stay in the air for days or weeks. PM10 can travel as little as 1 km or as much as 50 km. PM2.5 can travel much further – many hundreds of kilometers.
Here is the important question. Which is more dangerous: PM2.5 or PM10?
When you inhale, you breathe in air along with any particles that are in the air. The air and the particles travel into your respiratory system i.e. your lungs and airway. Along the way, the particles can stick to the sides of your airway or travel deeper into your lungs.
The further the particles go, the worse the effect.
Bigger particles are more likely to stick to the sides or get wedged into one of the narrow passages deep in the lung. Smaller particles can pass through the smaller airways. Because PM2.5 travels deeper into the lungs and is made up of substances that are more toxic e.g. heavy metals and cancer causing organic compounds, it is far more dangerous than PM10. PM2.5 particles are so fine they can even enter the bloodstream.
So, because PM2.5 can penetrate deep into the lungs and is more toxic, measuring it is considered a more accurate reflection of air quality than simply measuring PM10.
The PSI readings that are updated every hour, on the hour, on NEA’s website do not take into account PM2.5 but are based solely on PM10. The hourly PSI readings that appear in the media, such as the screaming headline in Thursday’s (20 Jun) edition of The Straits Times: “RECORD PSI AT 10 PM 321 Plans in place if haze worsens” are, make no mistake, PM10 readings.
Is PSI obsolete?
PSI is just a name for an air quality index. The name is not as important as the computation behind it. In Singapore’s case, the computation is obsolete. Singapore’s PSI is based on an American model developed in the late 60’s. In 1999, with advances in technology and knowledge, the Americans replaced the PSI with the Air Quality Index (AQI) to incorporate new PM2.5 and ozone standards.
The Chinese experience
To illustrate how unpopular and antiquated the PSI is, consider that even China has switched to providing PM2.5 AQI readings [Link].
In the past, China gave only PM10 PSI readings, which the Chinese citizens rejected because they knew from the air they were breathing that the reading had to be much higher. So the Chinese people turned to the website of the American Embassy in Beijing for both hourly PM2.5 readings and hourly AIQ numbers based on those readings. This caused the Chinese government no end of embarrassment, so finally they too issued PM2.5 readings and AQI numbers according to their interpretation. Beginning early 2012, hourly air quality updates are now available online for more than 70 Chinese cities.
To be sure, the Chinese AQI interprets data somewhat less stringently than the American AQI, but it is still way better than the relic which is the PSI for the simple reason that the AQI incorporates PM2.5 whereas the PSI does not.
The Chinese experience mirrors what Singaporeans felt on Thursday morning (22 Jun) when they knew instinctively that the PSI could not be so low (‘Netizens accuse NEA of grossly understating PSI readings‘).
So this is the first way NEA ’smokes’ Singaporeans, by using an antiquated and inferior air quality indicator.
Giving 3-hour average numbers instead of 1-hour spot numbers
The second way NEA ’smokes’ Singaporeans is by giving out 3-hour average numbers instead of 1-hour spot numbers. This has the effect of smoothening out PSI numbers so that the real high is never known to the public. When the PSI hit a supposed high of 401 at 12pm yesterday (21 Jun), you can bet your last N95 mask that the real number was even higher.
How much higher you might ask? For the answer, we have to look at the actual 3-hour PSI posted on NEA’s website and study the “math” behind it.
For the mathematically inclined
Suppose:
A = (a + b + c)/3 where A = 3-hr PSI at 12pm, a = 1-hr PSI at 12pm, b = 1-hr PSI at 11am, c = 1-hr PSI at 10am
B = (b + c + d)/3 where B = 3-hr PSI at 11am, b = 1-hr PSI at 11am, c = 1-hr PSI at 10am, d = 1-hr PSI at 9am
C = (c + d + e)/3 where C = 3-hr PSI at 10am, c = 1-hr PSI at 10am, d = 1-hr PSI at 9am, e = 1-hr PSI at 8am
D = (d + e + f)/3 where D = 3-hr PSI at 9am, d = 1-hr PSI at 9am, e = 1-hr PSI at 8am, f = 1-hr PSI at 7am
E = (e + f + g)/3 where E = 3-hr PSI at 8am, e = 1-hr PSI at 8am, f = 1-hr PSI at 7am, g = 1-hr PSI at 6am
NEA is very sneaky because if you want to calculate the 1-hour PSI at any time (what every Singaporean wants to know) from the above, you will find it is mathematically impossible.
A, B, C, D, E are known values, being “PSI readings” published by NEA every hour on the hour. However, a, b, c, d, e, f, g – the 1-hour PSI values – are all unknowns. To calculate exactly the 1-hour PSI values i.e. a, b, c, d, e, f, g, there must be at least as many simultaneous equations as there are unknowns. Unfortunately, there are too few simultaneous equations and too many unknowns. For example, if you take the first 3 equations above involving A, B and C, you get 3 equations and 5 unknowns; if you take all 5 equations involving A, B, C, D and E, you get 5 equations and 7 unknowns. So, what Singaporeans call “the real PSI” remains a secret.
To prove “the real PSI” remains a secret, let us assume that the 3-hour PSI is a constant 180 throughout the day. It is tempting to think that the 1-hour PSI must also be constant i.e. 180 throughout, but no, it could be that as well as a recurring 170, 190, 180, 170, 190, 180, 170, 190, 180, etc.
Nevertheless there is useful information to glean from all the 3-hour PSI readings, such as:
A – B = (a-d)/3
B – C = (b-e)/3
C – D = (c-f)/3, etc
Now C – D = (c-f)/3 implies c – f = 3(C – D). This is where it gets interesting.
Consider the 3-hour PSI readings for yesterday morning (21 Jun) from 4am to 12pm. They are 104 (4am), 96 (5am), 94 (6am), 111 (7am), 158 (8am), 256 (9am), 367 (10am), 400 (11am), 401 (12pm).
Substituting C = 367 and D = 256 into c – f = 3(C – D), we get c – f = 3(367 – 256) = 3(111) = 333. This means there was a big jump in the 1-hour PSI of exactly 333 from 7am to 10am. Although we do not know the exact 1-hour PSI value for 7am (which we have seen is impossible to calculate), since everyone knows the sky was somewhat hazy, we can safely assume it to have been about 138 which means the 1-hour PSI for 11am was 138 + 333 = 471!
So, the 1-hour PSI readings for yesterday morning were likely in the region of 87 (4am), 90 (5am), 105 (6am), 138 (7am), 231 (8am), 399 (9am), 471 (10am), 330 (11am), 402 (12pm). This means the “real PSI” peaked around 471 around 10am!
Data Removal
The third way in which NEA ’smokes’ Singaporeans is by denying them information.
If you visit NEA’s website just after midnight, you will be shocked to find just one 3-hour PSI reading staring you in the face. If you want to know what the PSI reading was an hour ago at 11pm, or 2 hours ago at 10pm, sorry hor, who ask you to click so late, why you never click earlier, you die your business.
You search in vain for the missing data but alas, it has left the public domain and is safely in the pocket of the PAP. Old PSI readings are not archived or cached. This is to emasculate Singaporeans, for knowledge is power.
Confusion
The fourth way NEA ’smokes’ Singaporeans is by confusing them.
Look at NEA’s PSI webpage. See how the large blue words “PM2.5 Readings” take almost centrestage?
You would think from a quick glance that the numbers beneath “PM2.5 readings” are… PM2.5 readings! How deceptive!
It is only upon reading the “fine print” after the numbers that you realise they are “PSI readings based on PM10 concentrations only”.
Another way NEA sows confusion is by calling PSI numbers “PSI readings”. Does NEA even know what it is talking about, one wonders.
Do PM Lee and Ministers Shanmugam and Vivian know what they are talking about? Or are they all charlatans?
PSI is not a reading. PSI is a number, a value, a calculation derived from a formula and based on measurements or readings.
The amount of PM2.5 or PM10 in the air is a reading. The amount of sulphur dioxide, carbon monoxide, nitrogen dioxide and ozone in the air, they are readings. These five readings or measurements are periodically fed into the AQI or PSI formula to obtain the AQI or PSI number, value or figure.
Conclusion
The American AQI is the gold standard of air quality indicators. It takes into account hazardous PM2.5 particulates on an hourly basis and interprets the data stringently. Singapore should junk the outdated PSI asap and adopt the latest American model.
For now though, as long as the PAP is sleeping, Singaporeans will have to be content with the PM2.5 values that NEA publishes 3 times a day – at 8am, 12pm and 4pm – and figure out how dangerous or safe the air is using this excellent AQI Calculator.
A link circulating around...
dunno if its a repost...
here it is
NEA
Singapore’s 3-hourly Pollutant Standards Index (PSI) smashed the previous record of 371 set on Thursday (20 Jun) to hit a new high of 401 yesterday (21 Jun) at 12pm.
On Wednesday, the record was 321, set at 10pm. On 3 consecutive days, the PSI set 3 records which means the haze is not only the worst in Singapore’s history, it is getting worse by the day!
To add insult to injury, the National Environment Agency (NEA) in charge of measuring the amount of pollutants in the air appears to be ’smoking’ (pun intended; Singlish for bluffing, deceiving, misleading) Singaporeans.
Using PM10 instead of PM2.5 to calculate PSI
NEA currently bases its “PSI readings” on PM10 only. As it says on its website, “The 3hr PSI readings are calculated based on PM10 concentrations only” (‘NEA’s PSI webpage‘).
What is PM10? Airborne pollutants come in big sizes and small. The big particles are between 2.5 and 10 micrometres in size i.e. 25 to 100 times thinner than a human hair. These particles are called PM10 (pronounced “P M ten”) which stands for Particulate Matter up to 10 micrometres.
Particulate matter – also known as atmospheric particulate matter or simply particulates – are tiny pieces of solid or liquid matter associated with the earth’s atmosphere.
The symbol for micrometre is µm (a symbol found on NEA’s website). 1 micrometre or 1 micron is one-millionth of a metre.
PM10 is also called “respirable suspended particle” or RSP since RSP are particles with a diameter of up to 10 µm.
What is PM2.5? You guessed it, PM2.5 (pronounced “P M two point five”) as in Particulate Matter up to 2.5 µm in size are the relatively small airborne pollutants.
PM2.5 is also known as fine particles since fine particles have a diameter of 2.5 µm or less.
Difference between PM10 and PM2.5
Fine particles i.e. PM2.5 are lighter and stay in the air longer and travel further than PM10. PM10 can stay in the air for minutes or hours while PM2.5 can stay in the air for days or weeks. PM10 can travel as little as 1 km or as much as 50 km. PM2.5 can travel much further – many hundreds of kilometers.
Here is the important question. Which is more dangerous: PM2.5 or PM10?
When you inhale, you breathe in air along with any particles that are in the air. The air and the particles travel into your respiratory system i.e. your lungs and airway. Along the way, the particles can stick to the sides of your airway or travel deeper into your lungs.
The further the particles go, the worse the effect.
Bigger particles are more likely to stick to the sides or get wedged into one of the narrow passages deep in the lung. Smaller particles can pass through the smaller airways. Because PM2.5 travels deeper into the lungs and is made up of substances that are more toxic e.g. heavy metals and cancer causing organic compounds, it is far more dangerous than PM10. PM2.5 particles are so fine they can even enter the bloodstream.
So, because PM2.5 can penetrate deep into the lungs and is more toxic, measuring it is considered a more accurate reflection of air quality than simply measuring PM10.
The PSI readings that are updated every hour, on the hour, on NEA’s website do not take into account PM2.5 but are based solely on PM10. The hourly PSI readings that appear in the media, such as the screaming headline in Thursday’s (20 Jun) edition of The Straits Times: “RECORD PSI AT 10 PM 321 Plans in place if haze worsens” are, make no mistake, PM10 readings.
Is PSI obsolete?
PSI is just a name for an air quality index. The name is not as important as the computation behind it. In Singapore’s case, the computation is obsolete. Singapore’s PSI is based on an American model developed in the late 60’s. In 1999, with advances in technology and knowledge, the Americans replaced the PSI with the Air Quality Index (AQI) to incorporate new PM2.5 and ozone standards.
The Chinese experience
To illustrate how unpopular and antiquated the PSI is, consider that even China has switched to providing PM2.5 AQI readings [Link].
In the past, China gave only PM10 PSI readings, which the Chinese citizens rejected because they knew from the air they were breathing that the reading had to be much higher. So the Chinese people turned to the website of the American Embassy in Beijing for both hourly PM2.5 readings and hourly AIQ numbers based on those readings. This caused the Chinese government no end of embarrassment, so finally they too issued PM2.5 readings and AQI numbers according to their interpretation. Beginning early 2012, hourly air quality updates are now available online for more than 70 Chinese cities.
To be sure, the Chinese AQI interprets data somewhat less stringently than the American AQI, but it is still way better than the relic which is the PSI for the simple reason that the AQI incorporates PM2.5 whereas the PSI does not.
The Chinese experience mirrors what Singaporeans felt on Thursday morning (22 Jun) when they knew instinctively that the PSI could not be so low (‘Netizens accuse NEA of grossly understating PSI readings‘).
So this is the first way NEA ’smokes’ Singaporeans, by using an antiquated and inferior air quality indicator.
Giving 3-hour average numbers instead of 1-hour spot numbers
The second way NEA ’smokes’ Singaporeans is by giving out 3-hour average numbers instead of 1-hour spot numbers. This has the effect of smoothening out PSI numbers so that the real high is never known to the public. When the PSI hit a supposed high of 401 at 12pm yesterday (21 Jun), you can bet your last N95 mask that the real number was even higher.
How much higher you might ask? For the answer, we have to look at the actual 3-hour PSI posted on NEA’s website and study the “math” behind it.
For the mathematically inclined
Suppose:
A = (a + b + c)/3 where A = 3-hr PSI at 12pm, a = 1-hr PSI at 12pm, b = 1-hr PSI at 11am, c = 1-hr PSI at 10am
B = (b + c + d)/3 where B = 3-hr PSI at 11am, b = 1-hr PSI at 11am, c = 1-hr PSI at 10am, d = 1-hr PSI at 9am
C = (c + d + e)/3 where C = 3-hr PSI at 10am, c = 1-hr PSI at 10am, d = 1-hr PSI at 9am, e = 1-hr PSI at 8am
D = (d + e + f)/3 where D = 3-hr PSI at 9am, d = 1-hr PSI at 9am, e = 1-hr PSI at 8am, f = 1-hr PSI at 7am
E = (e + f + g)/3 where E = 3-hr PSI at 8am, e = 1-hr PSI at 8am, f = 1-hr PSI at 7am, g = 1-hr PSI at 6am
NEA is very sneaky because if you want to calculate the 1-hour PSI at any time (what every Singaporean wants to know) from the above, you will find it is mathematically impossible.
A, B, C, D, E are known values, being “PSI readings” published by NEA every hour on the hour. However, a, b, c, d, e, f, g – the 1-hour PSI values – are all unknowns. To calculate exactly the 1-hour PSI values i.e. a, b, c, d, e, f, g, there must be at least as many simultaneous equations as there are unknowns. Unfortunately, there are too few simultaneous equations and too many unknowns. For example, if you take the first 3 equations above involving A, B and C, you get 3 equations and 5 unknowns; if you take all 5 equations involving A, B, C, D and E, you get 5 equations and 7 unknowns. So, what Singaporeans call “the real PSI” remains a secret.
To prove “the real PSI” remains a secret, let us assume that the 3-hour PSI is a constant 180 throughout the day. It is tempting to think that the 1-hour PSI must also be constant i.e. 180 throughout, but no, it could be that as well as a recurring 170, 190, 180, 170, 190, 180, 170, 190, 180, etc.
Nevertheless there is useful information to glean from all the 3-hour PSI readings, such as:
A – B = (a-d)/3
B – C = (b-e)/3
C – D = (c-f)/3, etc
Now C – D = (c-f)/3 implies c – f = 3(C – D). This is where it gets interesting.
Consider the 3-hour PSI readings for yesterday morning (21 Jun) from 4am to 12pm. They are 104 (4am), 96 (5am), 94 (6am), 111 (7am), 158 (8am), 256 (9am), 367 (10am), 400 (11am), 401 (12pm).
Substituting C = 367 and D = 256 into c – f = 3(C – D), we get c – f = 3(367 – 256) = 3(111) = 333. This means there was a big jump in the 1-hour PSI of exactly 333 from 7am to 10am. Although we do not know the exact 1-hour PSI value for 7am (which we have seen is impossible to calculate), since everyone knows the sky was somewhat hazy, we can safely assume it to have been about 138 which means the 1-hour PSI for 11am was 138 + 333 = 471!
So, the 1-hour PSI readings for yesterday morning were likely in the region of 87 (4am), 90 (5am), 105 (6am), 138 (7am), 231 (8am), 399 (9am), 471 (10am), 330 (11am), 402 (12pm). This means the “real PSI” peaked around 471 around 10am!
Data Removal
The third way in which NEA ’smokes’ Singaporeans is by denying them information.
If you visit NEA’s website just after midnight, you will be shocked to find just one 3-hour PSI reading staring you in the face. If you want to know what the PSI reading was an hour ago at 11pm, or 2 hours ago at 10pm, sorry hor, who ask you to click so late, why you never click earlier, you die your business.
You search in vain for the missing data but alas, it has left the public domain and is safely in the pocket of the PAP. Old PSI readings are not archived or cached. This is to emasculate Singaporeans, for knowledge is power.
Confusion
The fourth way NEA ’smokes’ Singaporeans is by confusing them.
Look at NEA’s PSI webpage. See how the large blue words “PM2.5 Readings” take almost centrestage?
You would think from a quick glance that the numbers beneath “PM2.5 readings” are… PM2.5 readings! How deceptive!
It is only upon reading the “fine print” after the numbers that you realise they are “PSI readings based on PM10 concentrations only”.
Another way NEA sows confusion is by calling PSI numbers “PSI readings”. Does NEA even know what it is talking about, one wonders.
Do PM Lee and Ministers Shanmugam and Vivian know what they are talking about? Or are they all charlatans?
PSI is not a reading. PSI is a number, a value, a calculation derived from a formula and based on measurements or readings.
The amount of PM2.5 or PM10 in the air is a reading. The amount of sulphur dioxide, carbon monoxide, nitrogen dioxide and ozone in the air, they are readings. These five readings or measurements are periodically fed into the AQI or PSI formula to obtain the AQI or PSI number, value or figure.
Conclusion
The American AQI is the gold standard of air quality indicators. It takes into account hazardous PM2.5 particulates on an hourly basis and interprets the data stringently. Singapore should junk the outdated PSI asap and adopt the latest American model.
For now though, as long as the PAP is sleeping, Singaporeans will have to be content with the PM2.5 values that NEA publishes 3 times a day – at 8am, 12pm and 4pm – and figure out how dangerous or safe the air is using this excellent AQI Calculator.
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New 640i F12 cabrio owner, any whatapp group i can join?
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