Pollutant Standards Index#PSI in Singapore

The PSI is based on a scale devised by the United States Environmental Protection Agency (EPA) to provide a way for broadcasts and newspapers to report air quality on a daily basis. The PSI has been used in a number of countries including the United States and Singapore.

Since 1999, the US EPA has replaced the Pollution Standards Index (PSI) with the Air Quality Index (AQI) to incorporate new PM_2.5 and ozone standards.

Prior to 1 April 2014, Singapore published the PSI and the 1-hour PM_2.5 reading separately. This 3-hour PSI is unique to Singapore and was introduced in 1997 to provide additional air quality information which would better reflect a more current air quality situation.{{cite web|url=http://www.todayonline.com/singapore/singaporeans-haze-over-psi-readings|archive-url=https://web.archive.org/web/20130624081219/http://www.todayonline.com/singapore/singaporeans-haze-over-psi-readings|url-status=dead|archive-date=24 June 2013|title=Govt says it will move towards publishing 24-hour PSI, PM2.5 data on hourly basis|date=20 June 2013|publisher=TODAY|access-date=20 June 2013}} In 2016, the 3-hour PSI was phased out on the grounds that the 1-hour PM_2.5 reading was a better indicator of the current air quality.{{cite web|url=https://www.nea.gov.sg/our-services/pollution-control/air-pollution/faqs|title=National Environment Agency - Air Pollution FAQ}}

The PSI considers six air pollutants: sulphur dioxide (SO₂), particulate matter (PM₁₀), fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), carbon monoxide (CO) and ozone (O₃).

The concentrations of these pollutants in the ambient air are measured via a network of air monitoring stations located around Singapore.{{cite news|title=Written Reply by Dr Vivian Balakrishnan, Minister for the Environment and Water Resources to Parliamentary Question on Air Quality Reporting|url=https://app.mewr.gov.sg/web/contents/contents.aspx?contid=1718|access-date=15 April 2014|newspaper=Ministry of the Environment & Water Resources (Singapore)|date=10 September 2012|url-status=dead|archive-url=https://web.archive.org/web/20140416191750/https://app.mewr.gov.sg/web/contents/contents.aspx?contid=1718|archive-date=16 April 2014|df=dmy-all}}{{cite news |title=What is Air Quality Index AQI |url=https://www.business-standard.com/about/what-is-air-quality-index |work=Business Standard India}}

A sub-index value is computed for each pollutant based on the pollutant's ambient air concentration. The highest sub-index value is then taken as the PSI value. In other words, the PSI is determined by the pollutant with the most significant concentration.{{cite web|title=Computation of the Pollutant Standards Index (PSI)|url=http://www.haze.gov.sg/docs/default-source/faq/computation-of-the-pollutant-standards-index-%28psi%29.pdf|publisher=National Environment Agency of Singapore|access-date=15 April 2014}}

During haze episodes, PM_2.5 is the most significant pollutant.{{cite web|title=Frequently Asked Questions (FAQs) On Haze|url=http://www.haze.gov.sg/faq|publisher=National Environment Agency of Singapore|access-date=13 March 2016}}

The PSI is reported as a number on a scale of 0 to 500. The index figures enable the public to determine whether the air pollution levels in a particular location are good, unhealthy, hazardous or worse. The following PSI table is grouped by index values and descriptors, explaining the effects of the levels, according to Singapore's National Environment Agency (NEA).{{cite web| url = http://app2.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi| title = PSI Readings| access-date = 21 January 2014| publisher = National Environment Agency| url-status = dead| archive-url = https://web.archive.org/web/20140201145028/http://app2.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi| archive-date = 1 February 2014| df = dmy-all}}

Note: This chart reflects the guidelines used in Singapore and may differ from other countries. Health advisories are based on the US EPA's guidelines. Only the 24-hour PSI value and not the 3-hour PSI value is correlated to the health effects outlined in NEA's advisories.

{{main|Southeast Asian haze}}

Singapore has been regularly hit by smoke haze from forest fires in nearby Sumatra, Indonesia, brought over by wind. These forest fires have been attributed to the slash-and-burn method favoured by several large plantation owners to clear their land, as opposed to a more expensive and inconvenient mechanical approach using excavators and bulldozers.{{cite web|title=Singapore hit by highest haze levels in 16 years|url=https://www.bbc.co.uk/news/world-asia-22935068|publisher=BBC News|access-date=20 June 2013|date=18 June 2013}} In June 2013, severe haze hit Singapore, pushing the nation's PSI into Hazardous levels for the first time in its history.{{cite web|title=Haze in Singapore hits new high, PSI at 321 at 10pm|url=http://www.straitstimes.com/the-big-story/the-haze-singapore/story/haze-singapore-hits-new-high-psi-321-10pm-20130619|publisher=The Straits Times|access-date=20 June 2013|date=19 June 2013}} Presently, the highest 3-hour PSI reading on record in Singapore is 471 on 20 October 2015 at 11 pm (GMT+8).{{cite web|url=https://www.todayonline.com/world/asia/pm25-levels-hit-471-haze-situation-worsens|title=PM2.5 levels hit 471 as haze situation worsens|publisher=Today|date=20 October 2015}}

Singapore's computation of PSI and NEA's definitions of PSI ranges have been shown to correlate with a number of health outcomes including all-cause mortality.{{cite journal | title=Acute Health Impacts of the Southeast Asian Transboundary Haze Problem-A Review | date=6 September 2019 | last1=Cheong | first1=Kang Hao | last2=Ngiam | first2=Nicholas Jinghao | last3=Morgan | first3=Geoffrey G. | last4=Pek | first4=Pin Pin | last5=Tan | first5=Benjamin Yong-Qiang | last6=Lai | first6=Joel Weijia | last7=Koh | first7=Jin Ming | last8=Ong | first8=Marcus Eng Hock | last9=Ho | first9=Andrew Fu Wah | journal=International Journal of Environmental Research and Public Health | volume=16 | issue=18 | page=3286 | issn=1660-4601 | doi=10.3390/ijerph16183286 | pmc=6765769 | pmid=31500215| doi-access=free }} For sudden cardiac deaths, every increment of 30 units in PSI correlated with 8.15% increased risk of out-of-hospital cardiac arrest on the same day of exposure.{{Cite journal|last1=Ho|first1=Andrew Fu Wah|last2=Wah|first2=Win|last3=Earnest|first3=Arul|last4=Ng|first4=Yih Yng|last5=Xie|first5=Zhenjia|last6=Shahidah|first6=Nur|last7=Yap|first7=Susan|last8=Pek|first8=Pin Pin|last9=Liu|first9=Nan|date=November 2018|title=Health impacts of the Southeast Asian haze problem – A time-stratified case crossover study of the relationship between ambient air pollution and sudden cardiac deaths in Singapore|journal=International Journal of Cardiology|volume=271|pages=352–358|doi=10.1016/j.ijcard.2018.04.070|pmid=30223374|s2cid=52282745 }} This risk was found to remain elevated for 1–5 days after exposure. Similar short-term associations were subsequently found for acute myocardial infarction and acute ischemic stroke in analyses of national registries.{{Cite journal|last1=Ho|first1=Andrew F. W.|last2=Zheng|first2=Huili|last3=De Silva|first3=Deidre A.|last4=Wah|first4=Win|last5=Earnest|first5=Arul|last6=Pang|first6=Yee H.|last7=Xie|first7=Zhenjia|last8=Pek|first8=Pin P.|last9=Liu|first9=Nan|date=November 2018|title=The Relationship Between Ambient Air Pollution and Acute Ischemic Stroke: A Time-Stratified Case-Crossover Study in a City-State With Seasonal Exposure to the Southeast Asian Haze Problem|journal=Annals of Emergency Medicine|volume=72|issue=5|pages=591–601|doi=10.1016/j.annemergmed.2018.06.037|issn=1097-6760|pmid=30172448|s2cid=52144033}}{{Cite journal|last1=Ho|first1=Andrew Fu Wah|last2=Zheng|first2=Huili|last3=Earnest|first3=Arul|last4=Cheong|first4=Kang Hao|last5=Pek|first5=Pin Pin|last6=Seok|first6=Jeon Young|last7=Liu|first7=Nan|last8=Kwan|first8=Yu Heng|last9=Tan|first9=Jack Wei Chieh|date=2019-03-19|title=Time‐Stratified Case Crossover Study of the Association of Outdoor Ambient Air Pollution With the Risk of Acute Myocardial Infarction in the Context of Seasonal Exposure to the Southeast Asian Haze Problem|journal=Journal of the American Heart Association|volume=8|issue=6|pages=e011272|doi=10.1161/JAHA.118.011272|pmid=31112443|issn=2047-9980|pmc=6475051}} In terms of healthcare utilization, both country-wide Emergency Department visits and hospital admissions were increased per unit increase in PSI.{{Cite journal|last1=Chan|first1=Sze Ling|last2=Ho|first2=Andrew Fw|last3=Ding|first3=Huicong|last4=Liu|first4=Nan|last5=Earnest|first5=Arul|last6=Koh|first6=Mariko S.|last7=Chuah|first7=Jolyn St|last8=Lau|first8=Zheng Yi|last9=Tan|first9=Kelvin Bryan|last10=Zheng|first10=Huili|last11=Morgan|first11=Geoffrey G.|date=February 2020|title=Impact of Air Pollution and Trans-Boundary Haze on Nation-Wide Emergency Department Visits and Hospital Admissions in Singapore|url=https://www.ncbi.nlm.nih.gov/pubmed/32246709|journal=Annals of the Academy of Medicine, Singapore|volume=49|issue=2|pages=78–87|doi=10.47102/annals-acadmedsg.2019209|issn=0304-4602|pmid=32246709|s2cid=214786174|doi-access=free}}

{{reflist|30em}}

• [https://archive.today/20150925122632/http://www.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi/psi-readings-over-the-last-24-hours Past and present PSI readings in Singapore published by the NEA]

Category:Air pollution

Category:Environment of Singapore

Category:Environment of Malaysia

Category:United States Environmental Protection Agency

Category:Air quality index