User:Milton Beychok/Sandbox: Difference between revisions
imported>Milton Beychok No edit summary |
imported>Milton Beychok No edit summary |
||
Line 1: | Line 1: | ||
The '''Air Quality Index''' ('''AQI''') (also known as the '''Air Pollution Index''' ('''API''') or '''Pollutant Standard Index''' ('''PSI''')) is a number used by government agencies to characterize the quality of the air at a given location. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects. | The '''Air Quality Index''' ('''AQI''') (also known as the '''Air Pollution Index''' ('''API''') or '''Pollutant Standard Index''' ('''PSI''')) is a number used by government agencies to characterize the quality of the air at a given location. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects. | ||
Line 25: | Line 8: | ||
==Air Quality Indices by country== | ==Air Quality Indices by country== | ||
{| class=wikitable cellpadding="5" align="right" | |||
! Air Quality<br/>Health Index<br/>(AQI)|| Health Risk<br/>Category|| Color | |||
|- | |||
| 1 to 3|| Low||[[Image:ColorCode123.png]] | |||
|- | |||
| 4 to 6|| Moderate|| | |||
|- | |||
| 7 to 10|| High|| | |||
|- | |||
| 10+|| Very High|| | |||
|} | |||
===Canada=== | ===Canada=== | ||
The current health classifications used by the [[Meteorological Service of Canada]] (MSC) are as follows: | The current health classifications used by the [[Meteorological Service of Canada]] (MSC) are as follows: | ||
In the province of [[Ontario]], 31 is the upper limit for good and 32 the lower limit for moderate. Zero to 15 is classified as very good, and is given the color blue. | In the province of [[Ontario]], 31 is the upper limit for good and 32 the lower limit for moderate. Zero to 15 is classified as very good, and is given the color blue. |
Revision as of 16:09, 14 June 2009
The Air Quality Index (AQI) (also known as the Air Pollution Index (API) or Pollutant Standard Index (PSI)) is a number used by government agencies to characterize the quality of the air at a given location. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects.
To compute the AQI requires an air pollutant concentration from a monitor or model. The function used to convert from air pollutant concentration to AQI varies by pollutant, and is different in different countries.
In many countries, air quality index values are divided into ranges, and each range is assiged a descriptor and a color code. Standardized public health advisories are associated with each AQI range. An agency might also encourage members of the public to take public transportation or work from home when AQI levels are high.
Most air contaminants do not have an associated AQI. Many countries monitor ground-level ozone, particulates, sulfur dioxide, carbon monoxide and nitrogen dioxide and calculate air quality indices for these pollutants.
Air Quality Indices by country
Air Quality Health Index (AQI) |
Health Risk Category |
Color |
---|---|---|
1 to 3 | Low | |
4 to 6 | Moderate | |
7 to 10 | High | |
10+ | Very High |
Canada
The current health classifications used by the Meteorological Service of Canada (MSC) are as follows:
In the province of Ontario, 31 is the upper limit for good and 32 the lower limit for moderate. Zero to 15 is classified as very good, and is given the color blue.
Hong Kong
The Air Pollution Index (API) levels for Hong Kong are related to the measured concentrations of ambient respirable suspended particulate (RSP), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3) and nitrogen dioxide (NO2) over a 24-hour period based on the potential health effects of air pollutants.
An API level at or below 100 means that the pollutant levels are in the satisfactory range over 24 hour period and pose no acute or immediate health effects. However, air pollution consistently at "High" levels (API of 51 to 100) in a year may mean that the annual Hong Kong "Air Quality Objectives" for protecting long-term health effects could be violated. Therefore, chronic health effects may be observed if one is persistently exposed to an API of 51 to 100 for a long time.
"Very High" levels (API in excess of 100) means that levels of one or more pollutant(s) is/are in the unhealthy range. The Hong Kong Environmental Protection Department provides advice to the public regarding precautionary actions to take for such levels.
API |
Air Pollution Level |
Health Implications |
---|---|---|
0 - 25 | Low | None expected. |
26 - 50 | Medium | None expected for the general population. |
51 - 100 | High | Acute health effects are not expected but chronic effects may be observed if one is persistently exposed to such levels. |
100 - 200 | Very High | People with existing heart or respiratory illnesses may notice mild aggravation of their health conditions. Generally healthy individuals may also notice some discomfort. |
201 - 500 | Severe | People with existing heart or respiratory illnesses may experience significant aggravation of their symptoms. There may also be widespread symptoms in the healthy population (e.g. eye irritation, wheezing, coughing, phlegm and sore throats). |
China
China's State Environment Protection Agency (SEPA) is responsible for measuring the level of air pollution in China. As of 28 August 2008, SEPA monitors daily pollution level in 86 of its major cities. The Air Pollution Index (API) level is based on the level of 5 atmospheric pollutants, namely sulfur dioxide (SO2), nitrogen dioxide (NO2), suspended particulates (PM10), carbon monoxide (CO), and ozone (O3) measured at the monitoring stations throughout each city. [1]
API Mechanics
An individual score is assigned to the level of each pollutant and the final API is the highest of those 5 scores. The pollutants can be measured quite differently. SO2, NO2 and PM10 concentration are measured as average per day. CO and O3 are more harmful and are measured as average per hour. The final API value is calculated per day.
The scale for each pollutant is non-linear, as is the final API score. Thus an API of 100 does not mean twice the pollution of API at 50, nor does it mean twice as harmful. While an API of 50 from day 1 to 182 and API of 100 from day 183 to 365 does provide an annual average of 75, it does not mean the pollution is acceptable even if the benchmark of 100 is deemed safe. This is because the benchmark is a 24 hour target. The annual average must match against the annual target. It is entirely possible to have safe air every day of the year but still fail the annual pollution benchmark.[1]
API and Health Implications (Daily Targets)[1]
API | Air Pollution Level |
Health Implications |
---|---|---|
0 - 50 | Excellent | No health implications |
51 -100 | Good | No health implications |
101-150 | Slightly Polluted | Slight irrations may occur, individuals with breathing or heart problems should reduce outdoor exercise. |
151-200 | Lightly Polluted | Slight irrations may occur, individuals with breathing or heart problems should reduce outdoor exercise. |
201-250 | Moderately Polluted | Healthy people will be noticeably affected. People with breathing or heart problems will experience reduced endurance in activities. These individuals and elders should remain indoors and restrict activities. |
251-300 | Heavily Polluted | Healthy people will be noticeably affected. People with breathing or heart problems will experience reduced endurance in activities. These individuals and elders should remain indoors and restrict activities. |
300+ | Severely Polluted | Healthy people will experience reduced endurance in activities. There may be strong irritations and symptoms and may trigger other illnesses. Elders and the sick should remain indoors and avoid exercise. Healthy individuals should avoid out door activities. |
Malaysia
The air quality in Malaysia is reported as the API or Air Pollution Index. Four of the index's pollutant components (i.e., carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide) are reported in ppmv but PM10 particulate matter is reported in μg/m³.
Unlike the American AQI, the index number can exceed 500. Above 500, a state of emergency is declared in the reporting area. Usually, this means that non-essential government services are suspended, and all ports in the affected area closed. There may also be a prohibition on private sector commercial and industrial activities in the reporting area excluding the food sector.
For more information on the API reading please go here http://www.doe.gov.my/index.php?option=com_content&task=view&id=188&Itemid=370&lang=en
Mexico
The air quality in Mexico is reported in IMECAs. The IMECA is calculated using the measurements of average times of the chemicals ozone (O3), sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and particles lower than 10 micrometers (PM10).
Singapore
Singapore uses the Pollutant Standards Index to report on its air quality. [1] The PSI chart below is grouped by index values and descriptors, according to the National Environment Agency.[2]
PSI | Descriptor | General Health Effects |
---|---|---|
0 - 50 | Good | None |
51 - 100 | Moderate | Few or none for the general population |
101 - 200 | Unhealthy | Mild aggravation of symptoms among susceptible persons i.e. those with underlying conditions such as chronic heart or lung ailments; transient symptoms of irritation e.g. eye irritation, sneezing or coughing in some of the healthy population. |
201 - 300 | Very Unhealthy | Moderate aggravation of symptoms and decreased tolerance in persons with heart or lung disease; more widespread symptoms of transient irritation in the healthy population. |
301 - 400 | Hazardous | Early onset of certain diseases in addition to significant aggravation of symptoms in susceptible persons; and decreased exercise tolerance in healthy persons. |
Above 400 | Hazardous | PSI levels above 400 may be life-threatening to ill and elderly persons. Healthy people may experience adverse symptoms that affect normal activity. |
United Kingdom
AEA Technology issue air quality forecasts for the UK on behalf of DEFRA wherein the level of pollution is described either as an index (ranging from 1 to 10) or as a banding (low, moderate, high or very high). These levels are based on the health effects of each pollutant.
Index | Banding | Health Effect |
---|---|---|
1 - 3 |
Low |
Effects are unlikely to be noticed even by individuals who know they are sensitive to air pollutants. |
4-6 |
Moderate |
Mild effects, unlikely to require action, may be noticed amongst sensitive individuals. |
7-9 |
High |
Significant effects may be noticed by sensitive individuals and action to avoid or reduce these effects may be needed (e.g. reducing exposure by spending less time in polluted areas outdoors). Asthmatics will find that their 'reliever' inhaler is likely to reverse the effects on the lung. |
10 |
Very High | The effects on sensitive individuals described for 'High' levels of pollution may worsen. |
The forecast is produced for a number of different pollutants and their typical health effects are shown in the following table.
Pollutant | Health Effects at High Level |
---|---|
Nitrogen dioxide Ozone Sulphur dioxide |
These gases irritate the airways of the lungs, increasing the symptoms of those suffering from lung diseases. |
Particulates |
Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of heart and lung diseases |
Air Quality Index (AQI) |
Health Level Category |
Color Code |
---|---|---|
0 to 50 | Good | |
51 to 100 | Moderate | |
101 to 150 | Unhealthy for Sensitive Groups |
|
151 to 200 | Unhealthy | |
201 to 300 | Very Unhealthy | |
301 to 500 | Hazardous |
United States
The Air Quality Index (AQI) ranges, and the corresponding color codes and health level categories, used by the U.S. EPA, are provided in the adjacent table.
If multiple pollutants are measured at a monitoring site, then the largest or "dominant" AQI value is reported for the location.
The U.S. EPA has developed conversion calculators for the conversion of AQI values to concentration values and for the reverse conversion of concentrations to AQI values that are available online.[2][3]
A national map of the United States containing daily AQI forecasts across the nation, developed jointly by the U.S. EPA and NOAA is also available online.[4]
The Clean Air Act of 1990 requires the U.S. EPA to review its National Ambient Air Quality Standards every five years to reflect evolving health effects information. The Air Quality Index is adjusted periodically to reflect these changes.
Air pollutant concentration measurement units
In the United States, the concentrations of the air pollutants involved in the AQI are usually expressed as:
- Ozone and sulfur dioxides: ppbv = parts per billion (10 9) by volume = volume of pollutant gas per billion volumes of ambient air
- Carbon monoxide: ppmv = parts per million (10 6) by volume = volume of pollutant gas per million volumes of ambient air
- PM10, defined as particulate matter having an aerodynamic diameter of 10 μm (micrometer) or less: ug/m³ = micrograms of particulate matter per cubic metre of ambient air
- PM2.5, defined as particulate matter having an aerodynamic diameter of 2.5 μm (micrometer) or less: ug/m³ = micrograms of particulate matter per cubic metre of ambient air
See also
- Atmospheric dispersion modeling
- Emission standard
- European emission standards
- Smog
- U.S. National Ambient Air Quality Standards
References
External links
- AQI at airnow.gov - cross-agency U.S. Government site
- New Mexico Air Quality and API data - Example of how New Mexico Environment Department publishes their Air Quality and API data.
- AQI at Meteorological Service of Canada
- The UK Air Quality Archive
- The pollution index of the UK Met Office
- API at JAS (Malaysian Department of Environment)
- API at Hong Kong - Environmental Protection Department of the Government of the Hong Kong Special Administrative Region
- San Francisco Bay Area Spare-the-Air - AQI explanation
- Malaysia Air Pollution Index
- AQI in Thailand provinces and in Bangkok
- The American Lung Association declares EPA standards fall short.