Brian Barton
The Pollutant Standards Index (PSI) is an air quality index used in Singapore and several other countries. It is a number that indicates the level of pollutants in the air, helping the public determine whether the air pollution levels are good, unhealthy, hazardous, or worse. PSI is calculated by measuring the ambient air concentration of six pollutants and taking the highest sub-index value as the PSI value. The index was devised by the United States Environmental Protection Agency (EPA) to provide a simple way for newspapers and broadcasts to report air quality daily.
| Characteristics | Values |
|---|---|
| Purpose | To communicate to the public about outdoor air quality and health |
| Pollutants considered | Six: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) |
| Calculation | A sub-index value is computed for each pollutant based on its ambient air concentration, and the highest sub-index value is taken as the PSI value |
| Scale | 0 to 500 |
| Interpretation | The higher the PSI value, the higher the level of air pollution and the greater the health concern |
| Usage | Used in Singapore; previously used in the United States until it was replaced by the Air Quality Index (AQI) in 1999 |
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What You'll Learn
- The Pollutant Standards Index (PSI) is a type of air quality index used in Singapore
- PSI is based on a scale devised by the United States Environmental Protection Agency (EPA)
- PSI considers six air pollutants: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3)
- PSI is reported as a number on a scale of 0 to 500
- PSI helps determine whether air pollution levels are good, unhealthy, hazardous, etc
The Pollutant Standards Index (PSI) is a type of air quality index used in Singapore
Initially, PSI was based on five air pollutants, but since 1 April 2014, it has also included fine particulate matter (PM2.5). In addition to the PSI derived by averaging data collected over 24 hours, Singapore also publishes 1-hour PM2.5 concentrations every hour. 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. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality.
Singapore has been regularly affected 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. In June 2013, severe haze pushed Singapore's PSI into the hazardous category for the first time in its history. The highest 3-hour PSI reading on record in Singapore was 471 on 20 October 2015 at 11 pm (GMT+8). Singapore's computation of PSI and the National Environment Agency's (NEA) definitions of PSI ranges have been shown to correlate with a number of health outcomes, including all-cause mortality and increased risk of out-of-hospital cardiac arrest.
The PSI has been used in several countries, including the United States and Singapore. However, since 1999, the US EPA has replaced the Pollution Standards Index (PSI) with the Air Quality Index (AQI) to incorporate new PM2.5 and ozone standards. Singapore's unique 3-hour PSI was introduced in 1997 to provide additional air quality information and was phased out in 2016 in favour of the 1-hour PM2.5 reading, which was considered a better indicator of current air quality.
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PSI is based on a scale devised by the United States Environmental Protection Agency (EPA)
The Pollutant Standards Index (PSI) is a type of air quality index used in Singapore. It is a number used to indicate the level of pollutants in the air. PSI is determined by the pollutant with the most significant concentration.
PSI was initially based on five air pollutants, but since 2014 it has also included fine particulate matter (PM2.5). Singapore also publishes 1-hr PM2.5 concentrations every hour. The PSI is based on a scale of 0 to 500, devised by the United States Environmental Protection Agency (EPA). This scale was designed to provide a way for newspapers, broadcasts, and other media to report air quality on a daily basis.
The PSI considers six air pollutants: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). A sub-index value is computed for each pollutant based on its ambient air concentration. The highest sub-index value is then taken as the PSI value.
The PSI enables the public to determine whether the air pollution levels in a particular location are good, unhealthy, hazardous, or worse. For example, during haze episodes, PM2.5 is typically the most significant pollutant, and PSI values in this range can indicate an increased risk of out-of-hospital cardiac arrest.
The EPA has since replaced PSI with the Air Quality Index (AQI) to incorporate new PM2.5 and ozone standards. AQI is a tool for communicating about outdoor air quality and health, with six color-coded categories indicating the level of air pollution and associated health concerns. AQI values above 100 indicate unhealthy air quality, while values over 300 represent hazardous air quality.
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PSI considers six air pollutants: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3)
The Pollutant Standards Index (PSI) is a type of air quality index used in Singapore. It is a number used to indicate the level of pollutants in the air. PSI is based on a scale devised by the United States Environmental Protection Agency (EPA) to provide a way for newspapers and broadcasts to report air quality on a daily basis. The PSI considers six air pollutants: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3).
Sulphur dioxide (SO2) is a gas formed by the combustion of materials containing sulphur, such as coal, oil, and diesel. It is also produced by power plants and industrial facilities that burn fossil fuels. SO2 can irritate the respiratory system and exacerbate respiratory illnesses such as asthma.
Particulate matter (PM) refers to inhalable particles composed of sulphate, nitrates, ammonia, sodium chloride, black carbon, mineral dust, or water. PM can be of different sizes, but PM10 and PM2.5 are the most common in the regulatory framework and are relevant for health. PM10 refers to particles with a diameter of 10 microns or less, which can be inhaled into the lungs and induce adverse health effects. Sources of PM10 include dust from construction sites, landfills, agriculture, wildfires, industrial sources, wind-blown dust, pollen, and fragments of bacteria.
PM2.5, also known as fine particulate matter, refers to particles with a diameter of 2.5 microns or less. These particles are even smaller and can penetrate deep into the lungs, entering the bloodstream. PM2.5 is often derived from the combustion of gasoline, oil, diesel fuel, or wood. It is associated with a wide range of adverse health effects, including premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, and respiratory symptoms.
Nitrogen dioxide (NO2) is a reddish-brown gas that is soluble in water and a strong oxidant. It is formed from the combustion of fossil fuels, such as coal, oil, gas, and diesel, as well as from vehicle emissions and industrial processes. NO2 can irritate the respiratory system and contribute to the formation of ground-level ozone.
Carbon monoxide (CO) is a colourless and odourless gas produced by the incomplete combustion of carbonaceous fuels, such as wood, petrol, coal, natural gas, and kerosene. CO is dangerous because it binds to haemoglobin in the blood, reducing the blood's ability to carry oxygen, which can lead to serious health issues and even death.
Ozone (O3) is a major component of smog and is formed from photochemical reactions with pollutants such as volatile organic compounds, carbon monoxide, and nitrogen oxides emitted from vehicles and industry. Ground-level ozone can cause breathing problems, trigger asthma, reduce lung function, and lead to lung disease.
The concentrations of these six pollutants in the ambient air are measured via a network of air monitoring stations located around Singapore. The PSI value is determined by the pollutant with the most significant concentration. This information is then used to inform the public about the air quality and any potential health risks associated with the current levels of pollution.
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PSI is reported as a number on a scale of 0 to 500
The Pollutant Standards Index (PSI) is a type of air quality index used in Singapore. It is a number that indicates the level of pollutants in the air. The PSI is reported as a number on a scale of 0 to 500, with higher values indicating higher levels of air pollution and associated health risks.
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 considers six air pollutants: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3).
A sub-index value is computed for each pollutant based on its ambient air concentration, and the highest sub-index value is taken as the PSI value. This means that the PSI is determined by the pollutant with the most significant concentration. During haze episodes, PM2.5 is typically the most significant pollutant.
The PSI enables the public to determine the level of air pollution in a particular location and the associated health risks. For example, a PSI value of 0-50 indicates good air quality, while a PSI value above 300 represents hazardous air quality.
Singapore has been regularly affected by smoke haze from forest fires in nearby Sumatra, Indonesia, which has resulted in hazardous PSI levels. The PSI is an important tool for the public to stay informed about air quality and take necessary precautions to protect their health.
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PSI helps determine whether air pollution levels are good, unhealthy, hazardous, etc
The Pollutant Standards Index (PSI) is a type of air quality index initially used in Singapore and the United States. It is a number used to indicate the level of pollutants in the air, based on a scale devised by the United States Environmental Protection Agency (EPA). The PSI considers six air pollutants: sulphur dioxide (SO2), particulate matter (PM10), fine particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3).
The PSI helps determine whether air pollution levels are good, unhealthy, or hazardous. A sub-index value is computed for each pollutant based on its ambient air concentration, and the highest sub-index value is taken as the PSI value. The PSI is reported as a number on a scale of 0 to 500, with higher values indicating worse air quality. For example, a PSI value above 300 would indicate hazardous air quality, while a value below 50 would indicate good air quality.
Singapore, in particular, has faced challenges with smoke haze from nearby forest fires in Indonesia, which has pushed the country's PSI into the hazardous level on several occasions. The PSI is a useful tool for the public to understand the air pollution levels in their area and take necessary precautions.
Other countries have also developed their own air quality indices, such as the Air Quality Index (AQI) in the United States, which serves a similar purpose as the PSI. The AQI is designed to provide a simple, uniform way to report daily air quality conditions and is calculated based on the pollutant with the highest AQI value. The AQI includes six color-coded categories, each indicating a range of index values and the associated health concerns.
Overall, the PSI and similar air quality indices are important tools for monitoring and communicating air pollution levels, enabling governments and individuals to take appropriate actions to protect public health.
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