What Is the Highest Positive Reading I Can Have for an Index Value

Measure of pollution

Smog in Shanghai, Dec 1993—an example of air conditions typically rated as unhealthy

An air quality index (AQI) is used by government agencies^[1] to communicate to the public how polluted the air currently is or how polluted it is forecast to become.^{[2] [3]} Public health risks increase as the AQI rises. Different countries take their own air quality indices, corresponding to different national air quality standards. Some of these are the Air Quality Wellness Index (Canada), the Air Pollution Index (Malaysia), and the Pollutant Standards Index (Singapore).

An annotated satellite photo showing smoke from wildfires in Hellenic republic, giving rise to an elevated AQI downwind

Air Quality Index Information [edit]

Computation of the AQI requires an air pollutant concentration over a specified averaging period, obtained from an air monitor or model. Taken together, concentration and time represent the dose of the air pollutant. Health effects corresponding to a given dose are established past epidemiological research.^[4] Air pollutants vary in authorization, and the role used to catechumen from air pollutant concentration to AQI varies by pollutant. Its air quality index values are typically grouped into ranges. Each range is assigned a descriptor, a color code, and a standardized public health advisory.

The AQI can increase due to an increase of air emissions (for example, during blitz hour traffic or when there is an upwind woods fire or from a lack of dilution of air pollutants. Stagnant air, often caused past an anticyclone, temperature inversion, or low air current speeds lets air pollution remain in a local area, leading to high concentrations of pollutants, chemical reactions betwixt air contaminants and hazy atmospheric condition.^[v]

On a 24-hour interval when the AQI is predicted to be elevated due to fine particle pollution, an agency or public health organization might:

• advise sensitive groups, such equally the elderly, children, and those with respiratory or cardiovascular problems, to avoid outdoor exertion.^[half-dozen]
• declare an "action day" to encourage voluntary measures to reduce air emissions, such equally using public transportation.^[vii]
• recommend the employ of masks to keep fine particles from entering the lungs^[8]

During a period of very poor air quality, such as an air pollution episode, when the AQI indicates that acute exposure may crusade significant damage to the public health, agencies may invoke emergency plans that allow them to order major emitters (such as coal burning industries) to curtail emissions until the hazardous conditions abate.^[9]

Almost air contaminants do not have an associated AQI. Many countries monitor basis-level ozone, particulates, sulfur dioxide, carbon monoxide and nitrogen dioxide, and calculate air quality indices for these pollutants.^[10]

The definition of the AQI in a particular nation reflects the soapbox surrounding the development of national air quality standards in that nation.^[11] A website allowing government agencies anywhere in the world to submit their existent-time air monitoring data for display using a mutual definition of the air quality index has recently become available.^[12]

Indices by location [edit]

Australia [edit]

Each of usa and territories of Australia is responsible for monitoring air quality and publishing information in accord with the National Environment Protection (Ambient Air Quality) Measure (NEPM) standards.^[13]

Each state and territory publishes air quality information for individual monitoring locations, and nigh states and territories publish air quality indexes for each monitoring location.

Across Commonwealth of australia, a consistent approach is taken with air quality indexes, using a simple linear scale where 100 represents the maximum concentration standard for each pollutant, as fix by the NEPM. These maximum concentration standards are:

Pollutant	Averaging period	Maximum concentration standard
Carbon monoxide	8 hours	9 ppm
Nitrogen dioxide	1 hour	0.12 ppm
	ane year	0.03 ppm
Ozone	ane hour	0.10 ppm
	4 hours	0.08ppm
Sulphur dioxide	1 hour	0.20 ppm
	1 day	0.08 ppm
	i year	0.02 ppm
Lead	1 year	0.50 μg/m3
PM 10	1 mean solar day	50 μg/m3
	ane year	25 μg/mthree
PM ii.v	ane day	25 μg/chiliad3
	1 twelvemonth	8 μg/grand3

The air quality alphabetize (AQI) for an private location is simply the highest of the air quality alphabetize values for each pollutant being monitored at that location.

AQI bands, with health advice for each:^[14]

AQI	Description	Health communication
0–33	Very Good	Enjoy activities
34–66	Good	Enjoy activities
67–99	Off-white	People unusually sensitive to air pollution: Plan strenuous outdoor activities when air quality is better
100–149	Poor	Sensitive Groups: Cut dorsum or reschedule strenuous outdoor activities
150–200	Very Poor	Sensitive groups: Avoid strenuous outdoor activities. Anybody: Cut back or reschedule strenuous outdoor activities
200+	Hazardous	Sensitive groups: Avoid all outdoor physical activities. Anybody: Significantly cut back on outdoor concrete activities

Canada [edit]

Air quality in Canada has been reported for many years with provincial Air Quality Indices (AQIs). Significantly, AQI values reflect air quality management objectives, which are based on the lowest doable emissions rate, rather than exclusive business organisation for human health. The Air Quality Health Index (AQHI) is a scale designed to help empathise the impact of air quality on wellness. It is a health protection tool used to brand decisions to reduce short-term exposure to air pollution by adjusting activeness levels during increased levels of air pollution. The Air Quality Health Alphabetize also provides advice on how to improve air quality by proposing a behavioral change to reduce the environmental footprint. This alphabetize pays particular attending to people who are sensitive to air pollution. It provides them with advice on how to protect their health during air quality levels associated with low, moderate, high and very high wellness risks.

The AQHI provides a number from ane to 10+ to indicate the level of wellness risk associated with local air quality. On occasion, when the amount of air pollution is abnormally high, the number may exceed 10. The AQHI provides a local air quality electric current value every bit well equally a local air quality maximums forecast for today, tonight, and tomorrow, and provides associated wellness advice.^[15]

1

2

3

four

five

vi

7

viii

9

10

+

Adventure:

Depression (i–3)

Moderate (4–6)

High (vii–10)

Very loftier (above ten)

Health Risk	Air Quality Wellness Alphabetize	Health Messages
		At Risk population	*General Population
Low	1–3	Enjoy your usual outdoor activities.	Ideal air quality for outdoor activities
Moderate	4–6	Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms.	No need to modify your usual outdoor activities unless you feel symptoms such as coughing and pharynx irritation.
High	7–x	Reduce or reschedule strenuous activities outdoors. Children and the elderly should besides take it easy.	Consider reducing or rescheduling strenuous activities outdoors if you lot experience symptoms such as coughing and throat irritation.
Very high	Above 10	Avoid strenuous activities outdoors. Children and the elderly should too avert outdoor concrete exertion.	Reduce or reschedule strenuous activities outdoors, especially if yous experience symptoms such as coughing and throat irritation.

Prc [edit]

Hong Kong [edit]

On December 30, 2013, Hong Kong replaced the Air Pollution Index with a new index called the Air Quality Health Index.^[16] This index, reported past the Ecology Protection Department, is measured on a scale of 1 to x+ and considers four air pollutants: ozone; nitrogen dioxide; sulphur dioxide and particulate matter (including PM10 and PM2.v). For any given 60 minutes the AQHI is calculated from the sum of the percentage backlog risk of daily hospital admissions attributable to the 3-hour moving boilerplate concentrations of these four pollutants. The AQHIs are grouped into five AQHI wellness risk categories with wellness advice provided:^[17]

Health risk category	AQHI
Low	1
	2
	3
Moderate	4
	five
	vi
Loftier	vii
Very High	8
	9
	ten
Serious	10+

Each of the health gamble categories has communication associated with it. At the low and moderate levels the public are advised that they can continue normal activities. For the loftier category, children, the elderly and people with heart or respiratory illnesses are advised to reduce outdoor physical exertion. Above this (very high or serious), the general public are besides advised to reduce or avoid outdoor physical exertion.

China [edit]

China's Ministry of Environmental Protection (MEP) is responsible for measuring the level of air pollution in China. As of January i, 2013, MEP monitors daily pollution level in 163 of its major cities. The AQI level is based on the level of six atmospheric pollutants, namely sulfur dioxide (So₂), nitrogen dioxide (NO₂), suspended particulates smaller than x μm in aerodynamic diameter (PM₁₀),^[xviii] suspended particulates smaller than 2.5 μm in aerodynamic diameter (PM_2.five),^[eighteen] carbon monoxide (CO), and ozone (O₃) measured at the monitoring stations throughout each city.^[nineteen]

AQI mechanics

An individual score (Private Air Quality Index, IAQI) is assigned to each pollutant and the final AQI is the highest of these vi scores. The concluding AQI value can be calculated either per hour or per 24 hours. The concentrations of pollutants can be measured quite differently. If the AQI value is calculated hourly, then And so₂, NO₂, CO concentrations are measured every bit average per 24h, O₃ concentration is measured as average per hour and the moving average per 8h, PM_2.5 and PM_x concentrations are measured equally boilerplate per hr and per 24h. If the AQI value is calculated per 24h, and then SO₂, NO_two, CO, PM_2.v and PM₁₀ concentrations are measured as average per 24h, while O₃ concentration is measured equally the maximum 1h average and the maximum 24h moving average. The IAQI of each pollutant is calculated according to a formula published past the MEP.^[19]

The score for each pollutant is non-linear, as is the concluding AQI score. Thus an AQI of 300 does not hateful twice the pollution of AQI at 150, nor does it mean the air is twice as harmful. The concentration of a pollutant when its IAQI is 100 does non equal twice its concentration when its IAQI is 50, nor does it mean the pollutant is twice as harmful. While an AQI of 50 from day 1 to 182 and AQI 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 accounted safe. Because the benchmark is a 24-hour target, and the almanac boilerplate must lucifer the almanac target, it is entirely possible to accept safe air every day of the year but still fail the almanac pollution benchmark.^[19]

AQI and health implications (HJ 633—2012) ^[nineteen]

AQI	Air Pollution Level	Air Pollution Category	Health Implications	Recommended Precautions
0–50	Level 1	Excellent (好极了)	No health implications.	Everyone can continue their outdoor activities normally.
51–100	Level ii	Good (良好)	Some pollutants may slightly affect very few hypersensitive individuals.	Only very few hypersensitive people should reduce outdoor activities.
101–150	Level 3	Lightly Polluted (輕度汚染)	Healthy people may feel slight irritations and sensitive individuals will be slightly affected to a larger extent.	Children, seniors and individuals with respiratory or heart diseases should reduce sustained and high-intensity outdoor exercises.
151–200	Level 4	Moderately Polluted (中度汚染)	Sensitive individuals will experience more serious conditions. The hearts and respiratory systems of healthy people may exist affected.	Children, seniors and individuals with respiratory or eye diseases should avoid sustained and loftier-intensity outdoor exercises. General population should moderately reduce outdoor activities.
201–300	Level 5	Heavily Polluted (重度汚染)	Healthy people will commonly bear witness symptoms. People with respiratory or center diseases will be significantly affected and will experience reduced endurance in activities.	Children, seniors and individuals with heart or lung diseases should stay indoors and avoid outdoor activities. General population should reduce outdoor activities.
>300	Level 6	Severely Polluted (嚴重)	Good for you people will feel reduced endurance in activities and may as well show noticeably strong symptoms. Other illnesses may be triggered in healthy people. Elders and the sick should remain indoors and avoid exercise. Healthy individuals should avert outdoor activities.	Children, seniors and the sick should stay indoors and avert physical exertion. General population should avoid outdoor activities.

Europe [edit]

The Common Air Quality Index (CAQI)^[xx] is an air quality index used in Europe since 2006.^[21] In Nov 2017, the European Environment Agency announced the European Air Quality Alphabetize (EAQI) and started encouraging its use on websites and for other ways of informing the public about air quality.^[22]

CAQI [edit]

As of 2012^[update], the Eu-supported projection CiteairII argued that the CAQI had been evaluated on a "large set" of information, and described the CAQI's motivation and definition. CiteairII stated that having an air quality index that would be like shooting fish in a barrel to nowadays to the general public was a major motivation, leaving aside the more complex question of a wellness-based index, which would require, for example, effects of combined levels of unlike pollutants. The main aim of the CAQI was to have an index that would encourage broad comparison across the EU, without replacing local indices. CiteairII stated that the "main goal of the CAQI is not to warn people for possible agin wellness effects of poor air quality merely to attract their attending to urban air pollution and its main source (traffic) and help them subtract their exposure."^[21]

The CAQI is a number on a calibration from 1 to 100, where a low value means adept air quality and a high value means bad air quality. The alphabetize is divers in both hourly and daily versions, and separately almost roads (a "roadside" or "traffic" index) or away from roads (a "background" index). As of 2012^[update], the CAQI had two mandatory components for the roadside index, NO_ii and PM_x, and three mandatory components for the background index, NO₂, PM₁₀ and O₃. Information technology also included optional pollutants PM_2.v, CO then₂. A "sub-alphabetize" is calculated for each of the mandatory (and optional if available) components. The CAQI is divers as the sub-index that represents the worst quality among those components.^[21]

Some of the cardinal pollutant concentrations in μg/g³ for the hourly background alphabetize, the corresponding sub-indices, and five CAQI ranges and verbal descriptions are as follows.^[21]

Qualitative name	Index or sub-index	Pollutant (hourly) concentration
		NO2 PPB	PMten μg/chiliadthree	O3 PPB	PM2.v (optional) μg/one thousand3
Very low	0–25	0–50	0–25	0–sixty	0–15
Depression	25–50	50–100	25–50	60–120	15–thirty
Medium	50–75	100–200	50–90	120–180	30–55
High	75–100	200–400	90–180	180–240	55–110
Very loftier	>100	>400	>180	>240	>110

Frequently updated CAQI values and maps are shown on world wide web.airqualitynow.eu^[23] and other websites.^[20] A separate Yr Average Common Air Quality Index (YACAQI) is also defined, in which different pollutant sub-indices are separately normalised to a value typically nigh unity. For instance, the yearly averages of NO_ii, PM_x and PM_2.5 are divided by 40 μg/mⁱⁱⁱ, 40 μg/m³ and 20 μg/mⁱⁱⁱ, respectively. The overall background or traffic YACAQI for a city is the arithmetic mean of a divers subset of these sub-indices.^[21]

India [edit]

The National Air Quality Index (AQI) was launched in New Delhi on September 17, 2014, under the Swachh Bharat Abhiyan.^[24]

The Central Pollution Control Board forth with State Pollution Control Boards has been operating National Air Monitoring Program (NAMP) covering 240 cities of the country having more than 342 monitoring stations.^[25] An Practiced Group comprising medical professionals, air quality experts, academia, advocacy groups, and SPCBs was constituted and a technical study was awarded to IIT Kanpur. IIT Kanpur and the Expert Group recommended an AQI scheme in 2014.^[26] While the earlier measuring index was limited to three indicators, the new index measures eight parameters.^[27] The continuous monitoring systems that provide information on near real-fourth dimension basis are installed in New Delhi, Mumbai, Pune, Kolkata and Ahmedabad.^[28]

There are half-dozen AQI categories, namely Practiced, Satisfactory, Moderately polluted, Poor, Very Poor, and Astringent. The proposed AQI volition consider 8 pollutants (PM_x, PM_2.5, NO_ii, SO₂, CO, O_three, NH_iii, and Pb) for which curt-term (upwards to 24-hourly averaging period) National Ambience Air Quality Standards are prescribed.^[29] Based on the measured ambient concentrations, respective standards and likely health impact, a sub-index is calculated for each of these pollutants. The worst sub-alphabetize reflects overall AQI. Likely wellness impacts for dissimilar AQI categories and pollutants have also been suggested, with primary inputs from the medical experts in the group. The AQI values and corresponding ambient concentrations (health breakpoints) equally well as associated likely wellness impacts for the identified eight pollutants are as follows:

AQI Category, Pollutants and Wellness Breakpoints

AQI Category (Range)	PM10 (24hr)	PM2.v (24hr)	NO2 (24hr)	O3 (8hr)	CO (8hr)	SOii (24hr)	NH3 (24hr)	Atomic number 82 (24hr)
Good (0–50)	0–50	0–thirty	0–40	0–50	0–ane.0	0–twoscore	0–200	0–0.5
Satisfactory (51–100)	51–100	31–sixty	41–fourscore	51–100	i.one–2.0	41–lxxx	201–400	0.v–ane.0
Moderately polluted (101–200)	101–250	61–90	81–180	101–168	2.1–10	81–380	401–800	one.1–2.0
Poor (201–300)	251–350	91–120	181–280	169–208	ten–17	381–800	801–1200	2.1–three.0
Very poor (301–400)	351–430	121–250	281–400	209–748	17–34	801–1600	1200–1800	3.1–3.v
Astringent (401–500)	430+	250+	400+	748+	34+	1600+	1800+	3.5+

AQI	Associated Wellness Impacts
Skilful (0–50)	Minimal impact
Satisfactory (51–100)	May cause pocket-size breathing discomfort to sensitive people.
Moderately polluted (101–200)	May cause breathing discomfort to people with lung disease such as asthma, and discomfort to people with centre illness, children and older adults.
Poor (201–300)	May crusade breathing discomfort to people on prolonged exposure, and discomfort to people with heart disease.
Very poor (301–400)	May crusade respiratory illness to the people on prolonged exposure. Effect may be more pronounced in people with lung and heart diseases.
Severe (401–500)	May cause respiratory impact even on salubrious people, and serious wellness impacts on people with lung/center disease. The health impacts may be experienced even during lite physical activity.

Mexico [edit]

The air quality in Mexico City is reported in IMECAs. The IMECA is calculated using the measurements of average times of the chemicals ozone (O_three), sulphur dioxide (And then_ii), nitrogen dioxide (NO₂), carbon monoxide (CO), particles smaller than 2.five micrometers (PM_2.5), and particles smaller than 10 micrometers (PM_ten).^[30]

Singapore [edit]

Singapore uses the Pollutant Standards Index to study on its air quality,^[31] with details of the calculation similar but not identical to those used in Malaysia and Hong Kong.^[32] The PSI chart below is grouped by index values and descriptors, according to the National Environment Agency.^[33]

PSI	Descriptor	General Health Effects
0–fifty	Practiced	None
51–100	Moderate	Few or none for the general population
101–200	Unhealthy	Mild aggravation of symptoms amidst susceptible persons i.e. those with underlying conditions such every bit chronic centre or lung ailments; transient symptoms of irritation e.g. eye irritation, sneezing or coughing in some of the good for you 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 pregnant bedevilment 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 agin symptoms that touch normal activeness.

Republic of korea [edit]

The Ministry building of Environment of Republic of korea uses the Comprehensive Air-quality Index (CAI) to describe the ambient air quality based on the health risks of air pollution. The index aims to help the public hands sympathise the air quality and protect people'south health. The CAI is on a scale from 0 to 500, which is divided into six categories. The higher the CAI value, the greater the level of air pollution. Of values of the five air pollutants, the highest is the CAI value. The index likewise has associated health effects and a colour representation of the categories every bit shown beneath.^[34]

CAI	Description	Health Implications
0–50	Good (좋음)	A level that will not impact patients suffering from diseases related to air pollution.
51–100	Moderate (보통)	A level that may have a meager impact on patients in case of chronic exposure.
101–250	Unhealthy (나쁨)	A level that may have harmful impacts on patients and members of sensitive groups (children, anile or weak people), and also cause the full general public unpleasant feelings.
251–500	Very unhealthy (매우 나쁨)	A level that may have a serious impact on patients and members of sensitive groups in example of acute exposure.

The N Seoul Tower on Namsan Mount in central Seoul, Due south Korea, is illuminated in blueish, from sunset to 23:00 and 22:00 in winter, on days where the air quality in Seoul is 45 or less. During the spring of 2012, the Tower was lit up for 52 days, which is 4 days more than in 2011.^[35]

United Kingdom [edit]

The most normally used air quality index in the Britain is the Daily Air Quality Index recommended by the Committee on the Medical Effects of Air Pollutants (COMEAP).^[36] This index has ten points, which are further grouped into 4 bands: low, moderate, high and very high. Each of the bands comes with communication for at-risk groups and the general population.^[37]

Air pollution banding	Value	Health messages for At-risk individuals	Wellness messages for General population
Low	i–3	Enjoy your usual outdoor activities.	Enjoy your usual outdoor activities.
Moderate	4–six	Adults and children with lung problems, and adults with eye problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors.	Bask your usual outdoor activities.
High	7–9	Adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and specially if they experience symptoms. People with asthma may discover they demand to use their reliever inhaler more frequently. Older people should likewise reduce physical exertion.	Anyone experiencing discomfort such as sore optics, cough or sore throat should consider reducing activity, particularly outdoors.
Very Loftier	x	Adults and children with lung problems, adults with middle issues, and older people, should avert strenuous concrete action. People with asthma may find they need to utilise their reliever inhaler more oftentimes.	Reduce physical exertion, particularly outdoors, especially if you lot experience symptoms such as coughing or sore throat.

The index is based on the concentrations of five pollutants. The index is calculated from the concentrations of the following pollutants: Ozone, Nitrogen Dioxide, Sulphur Dioxide, PM2.v (particles with an aerodynamic diameter less than 2.5 μm) and PM10. The breakpoints between index values are defined for each pollutant separately and the overall alphabetize is divers as the maximum value of the index. Different averaging periods are used for different pollutants.^[37]

Alphabetize	Ozone, Running 8 hourly mean (μg/miii)	Nitrogen Dioxide, Hourly hateful (μg/m3)	Sulphur Dioxide, 15 infinitesimal mean (μg/one thousand3)	PM2.5 Particles, 24 hour mean (μg/miii)	PMx Particles, 24 hr mean (μg/mthree)
i	0–33	0–67	0–88	0–11	0–xvi
2	34–66	68–134	89–177	12–23	17–33
3	67–100	135–200	178–266	24–35	34–l
4	101–120	201–267	267–354	36–41	51–58
5	121–140	268–334	355–443	42–47	59–66
half dozen	141–160	335–400	444–532	48–53	67–75
vii	161–187	401–467	533–710	54–58	76–83
viii	188-213	468–534	711–887	59–64	84–91
9	214–240	535–600	888–1064	65–seventy	92–100
10	≥ 241	≥ 601	≥ 1065	≥ 71	≥ 101

United States [edit]

PM_2.v 24-Hr AQI Loop, Courtesy US EPA

The Usa Environmental Protection Bureau (EPA) has adult an Air Quality Index that is used to written report air quality. This AQI is divided into six categories indicating increasing levels of health concern. An AQI value over 300 represents chancy air quality and below fifty the air quality is good.^[x]

Air Quality Alphabetize (AQI) Values	Levels of Wellness Concern	Colors
0 to 50	Skilful	Greenish
51 to 100	Moderate	Yellow
101 to 150	Unhealthy for Sensitive Groups	Orange
151 to 200	Unhealthy	Red
201 to 300	Very Unhealthy	Purple
301 to 500	Hazardous	Maroon

The AQI is based on the 5 "criteria" pollutants regulated nether the Clean Air Human action: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. The EPA has established National Ambient Air Quality Standards (NAAQS) for each of these pollutants in club to protect public health. An AQI value of 100 generally corresponds to the level of the NAAQS for the pollutant.^[10] The Clean Air Act (United states) (1990) requires the EPA to review its National Ambient Air Quality Standards every 5 years to reflect evolving health furnishings data. The Air Quality Index is adjusted periodically to reflect these changes.

Calculating the AQI [edit]

The air quality index is a piecewise linear function of the pollutant concentration. At the purlieus between AQI categories, there is a discontinuous bound of 1 AQI unit. To catechumen from concentration to AQI this equation is used:^[38]

${\displaystyle I={\frac {I_{high}-I_{low}}{C_{loftier}-C_{low}}}(C-C_{low})+I_{low}}$

(If multiple pollutants are measured, the calculated AQI is the highest value calculated from the higher up equation practical for each pollutant.)

where:

${\displaystyle I}$ = the (Air Quality) index,

${\displaystyle C}$ = the pollutant concentration,

${\displaystyle C_{low}}$ = the concentration breakpoint that is ≤ ${\displaystyle C}$ ,

${\displaystyle C_{high}}$ = the concentration breakpoint that is ≥ ${\displaystyle C}$ ,

${\displaystyle I_{low}}$ = the index breakpoint respective to ${\displaystyle C_{low}}$ ,

${\displaystyle I_{loftier}}$ = the index breakpoint corresponding to ${\displaystyle C_{high}}$ .

The EPA'due south table of breakpoints is:^{[39] [forty] [41]}

O3 (ppb)	O3 (ppb)	PMii.5 (μg/m3)	PM10 (μg/m3)	CO (ppm)	SOii (ppb)	NO2 (ppb)	AQI	AQI
Clow – Chigh (avg)	Clow – Chigh (avg)	Clow – Chigh (avg)	Cdepression – Chigh (avg)	Cdepression – Chigh (avg)	Clow – Chigh (avg)	Clow – Chigh (avg)	Idepression – Ihigh	Category
0–54 (8-hr)	—	0.0–12.0 (24-hr)	0–54 (24-hour)	0.0–4.4 (viii-hr)	0–35 (one-hr)	0–53 (one-hr)	0–50	Adept
55–70 (eight-hr)	—	12.1–35.4 (24-hr)	55–154 (24-hr)	4.5–9.iv (viii-hr)	36–75 (1-hr)	54–100 (1-hr)	51–100	Moderate
71–85 (8-hr)	125–164 (1-hr)	35.v–55.4 (24-hr)	155–254 (24-hour)	nine.5–12.iv (8-hour)	76–185 (ane-hour)	101–360 (1-hour)	101–150	Unhealthy for Sensitive Groups
86–105 (8-hr)	165–204 (one-hr)	55.five–150.four (24-60 minutes)	255–354 (24-hr)	12.5–15.four (8-hr)	186–304 (one-hr)	361–649 (ane-hour)	151–200	Unhealthy
106–200 (8-hr)	205–404 (ane-hr)	150.5–250.4 (24-hr)	355–424 (24-60 minutes)	15.5–thirty.4 (viii-hour)	305–604 (24-hr)	650–1249 (i-hr)	201–300	Very Unhealthy
—	405–504 (1-hr)	250.five–350.4 (24-hr)	425–504 (24-hour)	30.five–twoscore.iv (8-hr)	605–804 (24-hr)	1250–1649 (1-hr)	301–400	Hazardous
—	505–604 (1-hr)	350.5–500.4 (24-hr)	505–604 (24-60 minutes)	forty.5–fifty.4 (8-hr)	805–1004 (24-hr)	1650–2049 (i-hr)	401–500

Suppose a monitor records a 24-hour boilerplate fine particle (PM_ii.5) concentration of 26.4 micrograms per cubic meter. The equation above results in an AQI of:

${\displaystyle {\frac {100-51}{35.4-12.1}}(26.4-12.ane)+51=81.073}$

which rounds to index value of 81, corresponding to air quality in the "Moderate" range.^[42] To convert an air pollutant concentration to an AQI, EPA has developed a figurer.^[43]

If multiple pollutants are measured at a monitoring site, then the largest or "dominant" AQI value is reported for the location. The ozone AQI betwixt 100 and 300 is computed by selecting the larger of the AQI calculated with a 1-hour ozone value and the AQI computed with the 8-hour ozone value.

Viii-hour ozone averages practice not ascertain AQI values greater than 300; AQI values of 301 or greater are calculated with i-hr ozone concentrations. 1-hour So₂ values exercise non define higher AQI values greater than 200. AQI values of 201 or greater are calculated with 24-hour SO₂ concentrations.

Real-time monitoring data from continuous monitors are typically available equally i-hour averages. Yet, ciphering of the AQI for some pollutants requires averaging over multiple hours of information. (For example, calculation of the ozone AQI requires computation of an 8-hour average and computation of the PM_two.five or PM₁₀ AQI requires a 24-hr average.) To accurately reflect the current air quality, the multi-hr average used for the AQI computation should exist centered on the current time, but every bit concentrations of future hours are unknown and are difficult to estimate accurately, EPA uses surrogate concentrations to estimate these multi-hr averages. For reporting the PM_two.5, PM₁₀ and ozone air quality indices, this surrogate concentration is called the NowCast. The Nowcast is a particular type of weighted boilerplate that provides more weight to the most recent air quality data when air pollution levels are irresolute.^{[44] [45]} There is a gratis email subscription service for New York inhabitants – AirNYC.^[46] Subscribers become notifications about the changes in the AQI values for the selected location (e.thou. home address), based on air quality conditions.

Public availability of the AQI [edit]

Real time monitoring data and forecasts of air quality that are color-coded in terms of the air quality index are available from EPA'southward AirNow web site.^[47] Other organizations provide monitoring for members of sensitive groups such as asthmatics, children and adults over the historic period of 65.^[48] Historical air monitoring data including AQI charts and maps are available at EPA'southward AirData website.^[49] Detailed map about current AQI level and its two-mean solar day forecast is available from Aerostate web site.^[50]

History of the AQI [edit]

The AQI made its debut in 1968, when the National Air Pollution Control Administration undertook an initiative to develop an air quality index and to apply the methodology to Metropolitan Statistical Areas. The impetus was to draw public attention to the issue of air pollution and indirectly push responsible local public officials to have activity to control sources of pollution and enhance air quality within their jurisdictions.

Jack Fensterstock, the caput of the National Inventory of Air Pollution Emissions and Command Branch, was tasked to atomic number 82 the development of the methodology and to compile the air quality and emissions data necessary to test and calibrate resultant indices.^[51]

The initial iteration of the air quality alphabetize used standardized ambient pollutant concentrations to yield private pollutant indices. These indices were so weighted and summed to form a single full air quality index. The overall methodology could utilize concentrations that are taken from ambience monitoring data or are predicted by means of a improvidence model. The concentrations were then converted into a standard statistical distribution with a preset hateful and standard deviation. The resultant private pollutant indices are causeless to exist as weighted, although values other than unity can exist used. Too, the alphabetize can contain any number of pollutants although it was just used to combine And so₁₀, CO, and TSP because of a lack of available data for other pollutants.

While the methodology was designed to be robust, the applied application for all metropolitan areas proved to be inconsistent due to the paucity of ambient air quality monitoring data, lack of agreement on weighting factors, and non-uniformity of air quality standards across geographical and political boundaries. Despite these issues, the publication of lists ranking metropolitan areas achieved the public policy objectives and led to the future development of improved indices and their routine application.

Vietnam [edit]

On November 12, 2019, Vietnam Environs Administration issued Decision No. 1459/QD-TCMT on promulgating Technical Guidelines for calculation and publication of Vietnam Air Quality Index (VN_AQI).^[52]

AQI range	Air quality	Color
0 - fifty	Good (Tốt)	Greenish
51 - 100	Moderate (Trung bình)	Yellow
101 - 150	Bad (Kém)	Orangish
151 - 200	Unhealthy (Xấu)	Red
201 - 300	Very unhealthy (Rất xấu)	Royal
301 - 500	Chancy (Nguy hại)	Brown

See as well [edit]

• Air pollution
• Indoor air quality
• Air pollution forecasting

References [edit]

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2. ^ "NOAA's National Weather Service/Environmental Protection Agency - United States Air Quality Forecast Guidance". airquality.conditions.gov . Retrieved 2021-04-28 .
3. ^ "Archived copy". Archived from the original on 2014-10-xviii. Retrieved 2014-10-12 . {{cite web}}: CS1 maint: archived copy as title (link)
4. ^ "Step two - Dose-Response Assessment". Retrieved 20 August 2015.
5. ^ Myanmar government (2007). "Haze". Archived from the original on 27 January 2007. Retrieved 2007-02-eleven .
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7. ^ "Spare the Air - Summer Spare the Air". Archived from the original on 11 June 2018. Retrieved 20 August 2015.
8. ^ "FAQ: Apply of masks and availability of masks". Archived from the original on 2018-06-22. Retrieved xx August 2015.
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11. ^ Jay Timmons (13 Baronial 2014). "The EPA'south Latest Threat to Economic Growth". WSJ . Retrieved 20 August 2015.
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19. ^ ^{a b c d} "环境空气质量指数(AQI) 技术规定(试行)" [Technical Regulation on Ambient Air Quality Alphabetize (on trial)] (PDF). Ministry of Environmental Protection of the People'due south Republic of China (in Chinese). 2012-03-02. Archived from the original (PDF) on 2018-08-xxx. Retrieved 2018-02-02 .
20. ^ ^{a b} "Indices definition". Air quality. Retrieved 9 August 2012.
21. ^ ^{a b c d e} CiteairII — Common Information to European Air (2012-07-09). "CAQI Air quality index — Comparing Urban Air Quality across Borders – 2012" (PDF). Archived (PDF) from the original on 2016-02-22. Retrieved 2018-02-eighteen .
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23. ^ http://www.airqualitynow.eu
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27. ^ "National Air Quality Index (AQI) launched past the Surround Minister AQI is a huge initiative under 'Swachh Bharat'". Retrieved 20 August 2015.
28. ^ "India launches index to mensurate air quality". timesofindia-economictimes . Retrieved 20 August 2015.
29. ^ "::: Central Pollution Control Board :::". Retrieved 20 August 2015.
30. ^ "Dirección de Monitoreo Atmosférico". www.aire.cdmx.gob.mx . Retrieved 2016-06-xv .
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33. ^ "National Environment Agency". App2.nea.gov.sg. Archived from the original on 2011-11-25. Retrieved 2011-11-11 .
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35. ^ "Improved Air Quality Reflected in Due north Seoul Belfry". Chosun Ilbo. 18 May 2012. Archived from the original on iv March 2014. Retrieved 29 July 2012.
36. ^ COMEAP. "Review of the Uk Air Quality Index". COMEAP website. Archived from the original on 2011-11-xv.
37. ^ ^{a b} "Daily Air Quality Alphabetize". Air Uk Website. Defra.
38. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2020-10-26. Retrieved 2020-08-twenty . {{cite web}}: CS1 maint: archived copy as title (link)
39. ^ David Mintz (September 2018). Technical Assistance Document for the Reporting of Daily Air Quality – the Air Quality Index (AQI) (PDF). North Carolina: US EPA Office of Air Quality Planning and Standards. EPA-454/B-18-007. Retrieved fifteen September 2021.
40. ^ Revised Air Quality Standards For Particle Pollution And Updates To The Air Quality Index (AQI) (PDF). North Carolina: US EPA Office of Air Quality Planning and Standards. 2013.
41. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2015-x-06. Retrieved 2015-10-05 . {{cite spider web}}: CS1 maint: archived copy as title (link)
42. ^ "How does the EPA measure air quality?". www.purakamasks.com. 2019-02-06. Retrieved 2019-02-eleven .
43. ^ "AQI Reckoner". Retrieved seven October 2018.
44. ^ "AirNow API Documentation". Retrieved 20 Baronial 2015.
45. ^ "How are your ozone maps calculated?". Archived from the original on 21 August 2015. Retrieved 20 Baronial 2015.
46. ^ "AirNYC - Air quality in New York. Online". Archived from the original on 22 May 2017. Retrieved 10 Baronial 2017.
47. ^ "AirNow". Archived from the original on 24 November 2005. Retrieved 9 August 2012. .
48. ^ "Air Quality Lookup for Children, Seniors and Sensitive Groups". www.cleanairresources.com . Retrieved 2019-09-19 .
49. ^ "AirData". United states of america Environmental Protection Agency. Retrieved xx Baronial 2015.
50. ^ "Aerostate AQI map". aerostate.io. Archived from the original on 15 February 2018. Retrieved 13 Feb 2018.
51. ^ J.C Fensterstock et al., " The Development and Utilization of an Air Quality Alphabetize," Paper No. 69–73, presented at the 62nd Annual Meeting of the Air Pollution Control Assistants, June 1969.
52. ^ http://cem.gov.vn/tin-tuc-moi-truong/tong-cuc-moi-truong-ban-hanh-huong-dan-ky-thuat-tinh-toan-va-cong-bo-chi-then-conversation-luong-khong-khi-viet-nam

External links [edit]

Some of the post-obit websites display actively updated air quality alphabetize maps; others are archived versions of inactive websites:

• Global:
  • Worldwide Air Pollution: Real-time Air Quality Index Visual Map
• Europe:
  • CAQI- AirqualityNow
  • EAQI - European Environment Agency
  • The UK Air Quality Annal
• North America:
  • AQI at airnow.gov - cross-agency U.Due south. Regime site
  • New Mexico Air Quality and API information - Example of how New United mexican states Surround Department publishes their Air Quality and API information.
  • AQI at Meteorological Service of Canada
  • San Francisco Bay Area Spare-the-Air - AQI caption
• Asia:
  • CAI at Airkorea.or.kr - website of Republic of korea Environmental Management Corp.
  • API at JAS (Malaysian Department of Environment)
  • Malaysia Air Pollution Index (inactive equally of 19 February 2018^[update])
  • API at Hong Kong - Environmental Protection Section of the Government of the Hong Kong Special Authoritative Region (inactive as of 19 February 2018^[update])
  • AQI in Thailand
  • AQI in Vietnam
    • AQI in Hanoi
    • Unofficial PM25 AQI in Hanoi, Vietnam

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Source: https://en.wikipedia.org/wiki/Air_quality_index

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