Measurements

Introduction to Particulate Matter (PM)

Particulate matter is basically particles of solids or droplets of liquid. They are sometimes emitted directly from a source or are formed when pollutants in the atmosphere react with each other. These particles come in a wide range of sizes. Those that are smaller than 10 micrometers (i.e. PM10) are potentially harmful to our health for they can get into our lungs to do some serious damage. These PM10 particles actually damage human health and could cause many different respiratory effects on us. Also, these PM10 are produced from the haze with the many minute particles of dust and smog suspended in the air during the haze.

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Introduction to Measurements

Particulate matter is basically particles of solids or droplets of liquid. They are sometimes emitted directly from a source or are formed when pollutants in the atmosphere react with each other. These particles come in a wide range of sizes. Those that are smaller than 10 micrometers (i.e. PM10) are potentially harmful to our health for they can get into our lungs to do some serious damage. These PM10 particles actually damage human health and could cause many different respiratory effects on us. Also, these PM10 are produced from the haze with the many minute particles of dust and smog suspended in the air during the haze.

The six commonly found pollutants are:

• Sulphur Dioxide, a colourless gas when in high levels can cause humans respiratory problems.
• Carbon Monoxide, a toxic gas difficult to identify and is fatal at high levels. Has been known to cause headaches and impaired vision.
• Nitrogen Dioxide, agas that irritates the eye, nose and throat.
• Ground-level Ozone, causes respiratory problems from the mildest (cough) to the most severe (aggravated asthma).
• Violate Organic Compounds (VOC)
• Particulate Matter.(i.e. PM10/2.5), made up of fine particles that can cause a range of respiratory and heart
  problems depending on the size of the particles.

In order to measure the amount of pollutants in the air of a certain place, indexes are essential to enable environmentalists to express the degree of pollution in a way that is universally understood. With the indexes, media sources will be able to report air quality daily and enable the public to be aware of the air pollution levels. Across the globe, several types of air pollutant indexes exist. Here we will be introducing a few indexes sed in SEA countries and other countries.

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PSI (Pollutant Standard Index)

Singapore uses PSI to keep track of air quality. According to e-notes.com, it does so by “measuring the concentrations of pollutants in the air, in parts per million”. The table below describes the general health effects for the various levels of air pollution.

Fig 1.1 taken from http://app.nea.gov.sg/cms/htdocs/article.asp?pid=1251, with permission.

The PSI was developed by the United States Environmental Protection Agency (USEPA).

It incorporates only particulate matter smaller than 10 (PM10). In 1999, US EPA changed the PSI to the AQI so that it will be more accurate in calculating PM2.5 and ozone gases rather than just PM10.

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AQI (Air Quality Index)

The AQI is also an indicator of air quality at a specific place. It measures mainly the ground-level ozone, which is brought about by mainly human activities. It is mainly used in the US and Canada. Particulates (fine particles of either solid or liquid suspended in the air) may also include sulphur dioxide and nitrogen dioxide, a gas poisonous to inhale, but is still a common air pollutant!

According to AirNow, A cross-agency U.S. Government Web site, AQI is divided into the following 6 categories

Fig 2.1 modified from http://www.airnow.gov/index.cfm?action=aqibroch.aqi#2 with permission.

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Comparison between PSI and AQI

Let us now compare the difference between the two indexes discussed so far, the AQI and PSI.

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API (Air Pollution Index)

The API is used in Hong Kong and Malaysia. It measures the amount of the 4 main greenhouses gases (sulphur dioxide, carbon monoxide, ozone and nitrogen dioxide) in a day based on the possible health effects of air pollutant in Malaysia and 6 pollutants (similar to Malaysia with the addition of Violate Organic Compounds and PM10) in Hong Kong.

When level(s) of the pollutant(s) bridge(s) the healthy range, the indicator would rise to 100 or above. Advice pertaining to precautionary actions would then be disseminated to public by the Hong Kong Environmental Protection Department.

Fig 3.1 modified from http://cleanair.hk/eng/air_pollution.htm, with permission.

The table below shows the API Status indicator used in Malaysia

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Comparison between API and AQI

Let us now compare the difference between the two indexes discussed so far, the AQI and PSI.

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ISPU (Indeks Standar Pencemaran Udara)

(Translated, it means: Indonesia's Standard Air Pollution Index or Standard Air Pollution Index)

The ISPU is used by Indonesia in calculating the haze level. It basically takes into consideration 3 major pollutants that affect air quality which are namely: ozone, sulphur dioxide and PM10. The crux of the ISPU is the shows the air quality of major air pollutants and its potential threat to the general population’s health in one reading. Two other air quality indicators are also included, Ground Level Ozone and Toxic Air Release, but Ground level Ozone is reported separately due to changes in regulations regarding it.

(http://www.theharbinger.org/xviii/000411/envision1.html)

Fig 4.1 generated form data gathered at http://www.theharbinger.org/xviii/000411/envision1.html

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Conclusion

After researching the four pollutant indexes above, we are aware that there are other indexes in use across the globe that we have not explored. Our team then had a question in mind — why do people in all over the world have to create so many different indexes to measure air quality? We felt that if we could have one single, standardized index that would be used throughout all the countries, then it would make work easier for both the citizens and professionals (environmentalists, researchers, scientists). There would then be no more confusion between people of different nationality who want to know the air quality in each others country. Therefore, we felt that it definitely would be excellent if the governments or rulers of all countries arrange to come together to develop and agree on a standardized air quality index to facilitate the measurement of air quality in their respective countries.

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