Table 1. Air quality guideline and interim targets for PM: 24-hour mean

Air Quality
Makiko Nakata (Kinki University)and Sonoyo Mukai （The Kyoto College of Graduate Studies for Informatics）

Annualmean levelWHOinterimtarget 1(IT-1)

PM10(μg/m3 )

150

PM2.5
(μg/m3 )Basis forthe selected level75

Based on publishedrisk coefficientsfrom multicenterstudies and metaanalyses (about 5%
increase in shortterm mortality over
AQG)

50

Based on publishedrisk coefficientsfrom multicenterstudies and metaanalyses (about
2.5% increasein short-term
mortality over
AQG)

Abstract
Air quality standards are set in each country. The WHO air quality guidelines are designed to offer guidance in reducing thehealth impacts by regarding local circumstances carefully before using the guidelines directly as legal standards. This work
describes air quality guideline in general and the measurements of air quality.

1. Air quality guideline

suggesting that they quantify the risk ant locally relevantWHOinterimtarget 2(IT-2)

100

exposure levels and use those local estimates to guide policyAir quality means the state of the air around us. Good

Annualmean levelWHOinterimtarget 1(IT-1)WHO
interimtarget 2(IT-2)

PM10(μg/m3 )

70

50

PM2.5
(μg/m3 )Basis forthe selected level

35

These levels
are estimatedto be associatedwith about 15%
higher long-term
mortality than at
AQG levels.

25

In addition to other
health benefits，these levels lower
risk of premature
mortality byapproximately 6%(2-11%) comparedto IT-1.

15

In addition to other
health benefits，these levels reduce
mortality risk byapproximately
another 6% (2-11%)
compared to IT-2
levels.

10

These are thelowest levels at
which total，cardiopulmonary
and lung cancer
mortality havebeen shown toincrease withmore than 95%
confidence in
response to PM2.5
in the ACS study.
The use of thePM2.5 guideline ispreferred.

air quality refer to clean，clear，unpolluted air. Clean air

Since the publication of the second edition there has

is considered to be a basic requirement of human health.

been an increasing awareness among scientists and policy-

Poor air quality occurs when pollutants reach high enoughmakers of the global nature and magnitude of the publicconcentrations to endanger human health. Air pollution has

health problems posed by exposure to air pollution，based

become a serious problem worldwide. According to Worldon hundreds of new studies published in the scientifichealth report 2002，more than 2 million premature deaths

literature [4]. The project“Systematic review of healtheach year can be attributed to the effects of air pollution

aspects of air pollution in Europe”，carried out by the WHO[1]. The WHO air quality guidelines are designed to offer

Regional Office for Europe to support the development

guidance in reducing the health impacts. The guidelines areof the European Union's Clean Air for Europe (CAFE)

written for worldwide use，and are intended support actions

program in 2002–2004，concluded that this new evidence

aiming for the optical achievable level of air quality in orderwarranted revision of the air quality guidelines for PM，

to protect public health in different contexts. Air quality

ozone and nitrogen dioxide [5]. Of particular importance inInstruments for measuring air pollutants may vary greatly

standards are set in each country will vary according todeciding that the guidelines should apply worldwide wasin complexity and price，from the simplest passive sampler

speciﬁc approaches to balancing risk to health，technological

the substantial and growing evidence of the health effects

to the most advanced and expensive automatic remotefeasibility，economic considerations and other politicalof air pollution in the low- and middle-income countries ofmonitoring system based on light absorption spectroscopy

and social factors. The guidelines recommended by WHO

Asia，where air pollution levels are the highest. WHO'sof various kinds. Relatively simple equipment is usuallyacknowledge this heterogeneity and recognize in particularcomparative risk assessment quantified the burden of

adequate for determining background levels，estimating

that，in formulating policy targets，governments should

disease due to air pollution worldwide and，as noted above，

long-term average concentrations and observing trends.

consider their own local circumstances carefully before using

found the largest burden in the developing countries of Asia.

Passive samplers may also be adequate for undertaking

10 – 6 m) or 0.1 mm in diameter. However，the very largeWHOinterimtarget 3(IT-3)WHO air
qualityguidelines
(AQG)

75

50

37.5

A b o u t 1 . 2 %increase in shortterm mortality over
AQG

25

Based on relation
between 24-hour
and annual PMlevels

2. Air quality measurementWHOinterimtarget 3(IT-3)WHO air
qualityguidelines
(AQG)

30

20

The update of air quality guidelines set a guideline value

simple screening studies. For the complete determination ofparticles have a short atmospheric existence，tending to

The first edition of the WHO air quality guidelines forand interim targets for PM [6]. Based on known healthair pollution distributions and relative source impacts andfall out rapidly through gravity and wind-driven impaction

Europe was published in 1987 [2]，since when scientificeffects，both short-term (24-hour) guideline (Table 1) andthe operation of warning systems，however，more complex

processes. Thus in practice there are few particles in theknowledge about the effects of exposure to air pollution andlong-term (annual) guideline (Table 2) are needed for PM.

and advanced monitoring systems are needed. Also，whenatmosphere exceeding 20 μm in diameter，except in areas

the magnitude of its public health impact has increased

Besides the guideline values，three interim targets (IT)data are needed for verification of model performance，very close to sources of emission. Particulate matter can be

exponentially. In the early 1990s，the growing scientificwere deﬁned，which have been shown to be achievable withexpensive monitoring systems are usually needed.

separated from atmospheric gases by drawing air through aknowledge allowed WHO to initiate a process for revising the

successive and sustained abatement measures. Countries

Particulate air pollutants comprise material in solid or

ﬁlter ﬁne enough to retain the particles，or by accelerating

guidelines，resulting in publication of the second edition inmay ﬁnd these interim targets helpful in gauging progressliquid phase suspended in the atmosphere. Such particles

air through a jet that fires them at a fixed plate，onto

2000 [3]. The second edition considered health risk appraisal

over time in the difficult process of steadily reducing

can be either primary or secondary and cover a wide range

which the particles impact and are collected. Particulateof particulate matter (PM)，but did not set a guideline value

population exposures to PM.

the guidelines directly as legal standards.

18

making.

Table 2. Air quality guideline and interim targets for PM: annual meanof sizes. Newly formed secondary particles can be as small

air pollutants have very diverse chemical compositions

for PM，and instead offered guidance for risk managers in

as 1–2 nm in diameter (1 nm = 10 –9 m)，while coarse dustthat are highly dependent on their source. They are also

the form of a statistical model relating exposure to risk，and sea salt particles can be as large as 100 μm (1 μm =diverse in terms of particle size. PM10，PM2.5 and ultraﬁne

19

Table 1. Air quality guideline and interim targets for PM: 24-hour mean

Air Quality
Makiko Nakata (Kinki University)and Sonoyo Mukai （The Kyoto College of Graduate Studies for Informatics）

Annualmean levelWHOinterimtarget 1(IT-1)

PM10(μg/m3 )

150

PM2.5
(μg/m3 )Basis forthe selected level75

Based on publishedrisk coefficientsfrom multicenterstudies and metaanalyses (about 5%
increase in shortterm mortality over
AQG)

50

Based on publishedrisk coefficientsfrom multicenterstudies and metaanalyses (about
2.5% increasein short-term
mortality over
AQG)

Abstract
Air quality standards are set in each country. The WHO air quality guidelines are designed to offer guidance in reducing thehealth impacts by regarding local circumstances carefully before using the guidelines directly as legal standards. This work
describes air quality guideline in general and the measurements of air quality.

1. Air quality guideline

suggesting that they quantify the risk ant locally relevantWHOinterimtarget 2(IT-2)

100

exposure levels and use those local estimates to guide policyAir quality means the state of the air around us. Good

Annualmean levelWHOinterimtarget 1(IT-1)WHO
interimtarget 2(IT-2)

PM10(μg/m3 )

70

50

PM2.5
(μg/m3 )Basis forthe selected level

35

These levels
are estimatedto be associatedwith about 15%
higher long-term
mortality than at
AQG levels.

25

In addition to other
health benefits，these levels lower
risk of premature
mortality byapproximately 6%(2-11%) comparedto IT-1.

15

In addition to other
health benefits，these levels reduce
mortality risk byapproximately
another 6% (2-11%)
compared to IT-2
levels.

10

These are thelowest levels at
which total，cardiopulmonary
and lung cancer
mortality havebeen shown toincrease withmore than 95%
confidence in
response to PM2.5
in the ACS study.
The use of thePM2.5 guideline ispreferred.

air quality refer to clean，clear，unpolluted air. Clean air

Since the publication of the second edition there has

is considered to be a basic requirement of human health.

been an increasing awareness among scientists and policy-

Poor air quality occurs when pollutants reach high enoughmakers of the global nature and magnitude of the publicconcentrations to endanger human health. Air pollution has

health problems posed by exposure to air pollution，based

become a serious problem worldwide. According to Worldon hundreds of new studies published in the scientifichealth report 2002，more than 2 million premature deaths

literature [4]. The project“Systematic review of healtheach year can be attributed to the effects of air pollution

aspects of air pollution in Europe”，carried out by the WHO[1]. The WHO air quality guidelines are designed to offer

Regional Office for Europe to support the development

guidance in reducing the health impacts. The guidelines areof the European Union's Clean Air for Europe (CAFE)

written for worldwide use，and are intended support actions

program in 2002–2004，concluded that this new evidence

aiming for the optical achievable level of air quality in orderwarranted revision of the air quality guidelines for PM，

to protect public health in different contexts. Air quality

ozone and nitrogen dioxide [5]. Of particular importance inInstruments for measuring air pollutants may vary greatly

standards are set in each country will vary according todeciding that the guidelines should apply worldwide wasin complexity and price，from the simplest passive sampler

speciﬁc approaches to balancing risk to health，technological

the substantial and growing evidence of the health effects

to the most advanced and expensive automatic remotefeasibility，economic considerations and other politicalof air pollution in the low- and middle-income countries ofmonitoring system based on light absorption spectroscopy

and social factors. The guidelines recommended by WHO

Asia，where air pollution levels are the highest. WHO'sof various kinds. Relatively simple equipment is usuallyacknowledge this heterogeneity and recognize in particularcomparative risk assessment quantified the burden of

adequate for determining background levels，estimating

that，in formulating policy targets，governments should

disease due to air pollution worldwide and，as noted above，

long-term average concentrations and observing trends.

consider their own local circumstances carefully before using

found the largest burden in the developing countries of Asia.

Passive samplers may also be adequate for undertaking

10 – 6 m) or 0.1 mm in diameter. However，the very largeWHOinterimtarget 3(IT-3)WHO air
qualityguidelines
(AQG)

75

50

37.5

A b o u t 1 . 2 %increase in shortterm mortality over
AQG

25

Based on relation
between 24-hour
and annual PMlevels

2. Air quality measurementWHOinterimtarget 3(IT-3)WHO air
qualityguidelines
(AQG)

30

20

The update of air quality guidelines set a guideline value

simple screening studies. For the complete determination ofparticles have a short atmospheric existence，tending to

The first edition of the WHO air quality guidelines forand interim targets for PM [6]. Based on known healthair pollution distributions and relative source impacts andfall out rapidly through gravity and wind-driven impaction

Europe was published in 1987 [2]，since when scientificeffects，both short-term (24-hour) guideline (Table 1) andthe operation of warning systems，however，more complex

processes. Thus in practice there are few particles in theknowledge about the effects of exposure to air pollution andlong-term (annual) guideline (Table 2) are needed for PM.

and advanced monitoring systems are needed. Also，whenatmosphere exceeding 20 μm in diameter，except in areas

the magnitude of its public health impact has increased

Besides the guideline values，three interim targets (IT)data are needed for verification of model performance，very close to sources of emission. Particulate matter can be

exponentially. In the early 1990s，the growing scientificwere deﬁned，which have been shown to be achievable withexpensive monitoring systems are usually needed.

separated from atmospheric gases by drawing air through aknowledge allowed WHO to initiate a process for revising the

successive and sustained abatement measures. Countries

Particulate air pollutants comprise material in solid or

ﬁlter ﬁne enough to retain the particles，or by accelerating

guidelines，resulting in publication of the second edition inmay ﬁnd these interim targets helpful in gauging progressliquid phase suspended in the atmosphere. Such particles

air through a jet that fires them at a fixed plate，onto

2000 [3]. The second edition considered health risk appraisal

over time in the difficult process of steadily reducing

can be either primary or secondary and cover a wide range

which the particles impact and are collected. Particulateof particulate matter (PM)，but did not set a guideline value

population exposures to PM.

the guidelines directly as legal standards.

18

making.

Table 2. Air quality guideline and interim targets for PM: annual meanof sizes. Newly formed secondary particles can be as small

air pollutants have very diverse chemical compositions

for PM，and instead offered guidance for risk managers in

as 1–2 nm in diameter (1 nm = 10 –9 m)，while coarse dustthat are highly dependent on their source. They are also

the form of a statistical model relating exposure to risk，and sea salt particles can be as large as 100 μm (1 μm =diverse in terms of particle size. PM10，PM2.5 and ultraﬁne

19particle fractions are typically those measured within the

Beijing，Calcutta，Mexico City，Rio de Janeiro and Cairo，Because fine particles are much smaller than inhalable[4] World Health Organization Regional Office for Europe,

atmosphere for the purposes of health effects studies; thehigh levels of PM constitute a major problem. Air pollution

coarse particles，they can penetrate deeper into the lungs

Health aspects of air quality in Europe, Results from theﬁrst two fractions are also used for compliance monitoring.

levels are normally higher in developing countries than inand cause more severe effects on human health. Fine

WHO project “Systematic review of health aspects of air

Information about the ambient air pollution levels havehighly developed industrialized countries. PM levels indeed

particles are responsible for most visibility problems in Asia.

pollution in Europe”, 2004.

been based on measurements representative for different

present serious problems in the developing countries. PM10

Recent measurements in Beijing show PM2.5 concentrations

types of area and microenvironment，such as:concentrations have been reported from countries such as

averaging just over 100 μ g/m 3 . The monthly average• Trafﬁc，near roads and in streets;

India and Pakistan to be 4–5 times international air quality

concentrations varied between 61 μ g/m3 and 139 μ g/m3.

[6] World Health Organization Regional Office for Europe,• Urban areas，representative for the kilometre scale

limit values.

During air pollution episodes，daily mean PM2.5 values can

Air quality guidelines: global updated 2005, Report on areach 300μg/m3 [8].

Working Group meeting, Bonn, Germany, Copenhagen, 2005.

inside the urban airshed

The serious consequences of exposure to high levels of• Rural areas，away from local sources representative forresidential areas

twentieth century，when cities in Europe and the United

The selection of representative measurement sites，as wellStates experienced air pollution episodes. Subsequent clean

as the use of different measurement methods，has made theair legislation and actions reduced ambient air pollution ininterpretation and comparisons of the data difﬁcult.

pollution in developing countries of Asia, 2004.

[7] Krzyzanowski M., Schwela D.,“Patterns of air pollution indeveloping countries.”In: Holgate S. T. et al., eds. Air pollution

Acknowledgements

and health. San Diego, Academic Press, 1999:105-113.

This work was supported in part by the Global Change[8] Zheng M. et al. “Seasonal trends in PM2.5 source

many regions. The winter smog problems associated with

Observation Mission-Climate project by JAXA (no. JX -contributions in Beijing, China.”Atmospheric Environment,

Air quality measurements have revealed air pollution

coal combustion that were common in some cities during

PSPC-308878). This study was supported in part by the2005, 39:3967–3976.

problems in many of the major urban areas of the world.

the 1980s and early 1990s have been eradicated，and it

Global Environment Research Fund of the Ministry ofSome typical ranges of concentrations of the PM indicator

is now mainly emissions from traffic that pose the main

Environment，Japan (S-12)，and JSPS KAKENHI Grant

found in a selection of cities around the world arethreat to good air quality. The main sources for the present

Number 25340019 and 15K00528.

summarized in Table 3.

air pollution levels in western cities are traffic related.

Table 3. Ranges of annual average concentrations (μg/m3) of PM10 fordifferent regions， based on a selection of urban data.

Region20

urban ambient air pollution were made clear in the mid-

[5] Health Effects Institute, Health effects of outdoor air

PM10 (annual average
concentration)

Africa40-150Asia

35-220Australia/New Zealand

28-127

Canada/United States

20-60

Europe20-70

Latin America

30-129◆著者紹介

The previously frequent winter smog comprising a mixture【 References 】

of sulfurous compounds and particles (soot) have in this[1] World Health Organization, World health report 2002,

向井 苑生

Sonoyo Mukai

way changed over the years. Suspended particles，andReducing risks, promoting healthy life. Geneva, 2002.

especially submicron particles，combined with secondary[2] World Health Organization Regional Ofﬁce for Europe, Air

京都大学理学士，同大学院博士課程修了（宇宙物理学専攻），理学博士。

pollutants such as oxides of nitrogen and ozone，havequality guidelines for Europe, Copenhagen, 1987, WHO

元金沢工業大学教授，元近畿大学理工学部教授，元日本リモートセン

Regional Publications, European Series, No. 23.

シング学会理事，研究会会長，現評議員，元日本エアロゾル学会監事，

become a major problem in the large urban areas aroundthe world. At the same time，the populations of the rapidly[3] World Health Organization Regional Ofﬁce for Europe, Air

expanding megacities of Asia，Africa and Latin America are

quality guideline for Europe, 2nd ed. Copenhagen, 2000,

increasingly exposed to levels of ambient air pollution that

WHO Regional Publications, European Series, No. 91.

京都情報大学院大学教授。

常任理事，日本学術振興会専門委員。

rival and often exceed those experienced in industrializedcountries in the ﬁrst half of the twentieth century [7].
In general，the highest concentrations of PM10 werereported from Asia. This region also experiences relatively

The highest concentrations of PM10 are found in Africa，high background concentrations owing to forest fires andAsia and Latin America. Trends in air quality development

local emissions of particles from the use of poor-quality

differ in respect of the indicator pollutants. In Europe，

fuels. A well-known springtime meteorological phenomenon

PM10 levels had decreased by the end of last century but

throughout East Asia，causing the Asian dust，originateshave tended to rise again，which may be partially explained

from windblown dust from the arid region of Mongolia andby changing weather conditions. Even though large Asian

コラム

次のスーパームーンは？

いつごろだれが言い出したのか知らないが，今や普通名詞

り返すと，公転はｙ＝1.071714ｘ回である。それをExcelで簡になっている。天文学用語ではなく多分占い用語だろう。スー

単に計算してｘ，ｙが整数である最も簡単な組み合わせとし

パームーンとは満月と近地点通過が同じ日（何時間以内かはて x=14 y=15 が見つかる。すなわち1.071714に近い既約分

知らない）に起こることをいうそうだ。月はかなり扁平な公数は15 ／ 14ということで，月は満ち欠けを14回繰り返す間

China and adds to the general level of PM in the region.

転軌道を描き，その離心率は0.05もある。地球に最も近い時に地球の周りを15回公転する。スーパームーンは14 朔 望 月≒

cities have seen a slightly reduction in PM10 levels over

Chinese cities experience very high airborne particleの距離（近地点距離）と最も遠い時の距離（遠地点距離）の

1年1ケ月17日または18日ごとに起こることがわかる。ただし

the last few decades，PM10 and PM2.5 is still the major air

concentrations due to primary particles emitted from coal比は（1＋0.05）／（1－ 0.05）＝1.105

この計算は長期間続けているとズレが生じるのでご注意。

pollutant in Asia. Many of the large cities in Latin America，and biomass combustion and motor vehicle exhaust，as

サイズは通常時の5％増，最小時の10%増である。去年の8月

as well as Mexico City，still experience high levels of PM.

well as secondary sulfates formed by atmospheric chemical

10日に起こったが次はいつ起こるのだろうか？

でスーパームーンのAir pollution in megacities around the world has beenreaction from the sulfur dioxide emitted when coal is

an issue for several years. There were 24 megacities eachburned. PM2.5，whose diameter is 2.5 μ m or less is anwith more than 10 million inhabitants. Twelve of theseimportant indicator of risk to health from particulate

megacities are located in Asia，four in Latin America

pollution，and might also be a better indicator than PM10

and two in Africa: Cairo in Egypt and Lagos in Nigeria.

for anthropogenic suspended particles in many areas.

転のためだ。この数値の比は1.071714，すなわち満月から次According to the World Bank some African cities are growing

High PM2.5 readings will cause a spike in the mortalityの満月までに月は1.071714回公転するわけで，朔望をｘ回繰

by more than 10% annually. In many megacities，such asrate of patients suffering from heart and lung diseases.

月の満ち欠けの周期は朔望月＝29.54日で，月の公転周期は
近点月＝27.554日，満月から次の満月までの期間は月が地球の周りを１周する期間より約2日長い。その違いは地球の公

昨 年 8 月10日より14 朔望月後は今年9月28日である。正確には10時 46 分に近地点通過（35万 6877 km）で，11時51分に満月となる。ちなみに中秋の名月は旧暦の 8月15日で今年は満月の前日9月27日である。
なお，その次のスーパームーンは2016年11月14日に起こる。
ということで実はありふれた現象なのだ。

21

particle fractions are typically those measured within the

Beijing，Calcutta，Mexico City，Rio de Janeiro and Cairo，Because fine particles are much smaller than inhalable[4] World Health Organization Regional Office for Europe,

atmosphere for the purposes of health effects studies; thehigh levels of PM constitute a major problem. Air pollution

coarse particles，they can penetrate deeper into the lungs

Health aspects of air quality in Europe, Results from theﬁrst two fractions are also used for compliance monitoring.

levels are normally higher in developing countries than inand cause more severe effects on human health. Fine

WHO project “Systematic review of health aspects of air

Information about the ambient air pollution levels havehighly developed industrialized countries. PM levels indeed

particles are responsible for most visibility problems in Asia.

pollution in Europe”, 2004.

been based on measurements representative for different

present serious problems in the developing countries. PM10

Recent measurements in Beijing show PM2.5 concentrations

types of area and microenvironment，such as:concentrations have been reported from countries such as

averaging just over 100 μ g/m 3 . The monthly average• Trafﬁc，near roads and in streets;

India and Pakistan to be 4–5 times international air quality

concentrations varied between 61 μ g/m3 and 139 μ g/m3.

[6] World Health Organization Regional Office for Europe,• Urban areas，representative for the kilometre scale

limit values.

During air pollution episodes，daily mean PM2.5 values can

Air quality guidelines: global updated 2005, Report on areach 300μg/m3 [8].

Working Group meeting, Bonn, Germany, Copenhagen, 2005.

inside the urban airshed

The serious consequences of exposure to high levels of• Rural areas，away from local sources representative forresidential areas

twentieth century，when cities in Europe and the United

The selection of representative measurement sites，as wellStates experienced air pollution episodes. Subsequent clean

as the use of different measurement methods，has made theair legislation and actions reduced ambient air pollution ininterpretation and comparisons of the data difﬁcult.

pollution in developing countries of Asia, 2004.

[7] Krzyzanowski M., Schwela D.,“Patterns of air pollution indeveloping countries.”In: Holgate S. T. et al., eds. Air pollution

Acknowledgements

and health. San Diego, Academic Press, 1999:105-113.

This work was supported in part by the Global Change[8] Zheng M. et al. “Seasonal trends in PM2.5 source

many regions. The winter smog problems associated with

Observation Mission-Climate project by JAXA (no. JX -contributions in Beijing, China.”Atmospheric Environment,

Air quality measurements have revealed air pollution

coal combustion that were common in some cities during

PSPC-308878). This study was supported in part by the2005, 39:3967–3976.

problems in many of the major urban areas of the world.

the 1980s and early 1990s have been eradicated，and it

Global Environment Research Fund of the Ministry ofSome typical ranges of concentrations of the PM indicator

is now mainly emissions from traffic that pose the main

Environment，Japan (S-12)，and JSPS KAKENHI Grant

found in a selection of cities around the world arethreat to good air quality. The main sources for the present

Number 25340019 and 15K00528.

summarized in Table 3.

air pollution levels in western cities are traffic related.

Table 3. Ranges of annual average concentrations (μg/m3) of PM10 fordifferent regions， based on a selection of urban data.

Region20

urban ambient air pollution were made clear in the mid-

[5] Health Effects Institute, Health effects of outdoor air

PM10 (annual average
concentration)

Africa40-150Asia

35-220Australia/New Zealand

28-127

Canada/United States

20-60

Europe20-70

Latin America

30-129◆著者紹介

The previously frequent winter smog comprising a mixture【 References 】

of sulfurous compounds and particles (soot) have in this[1] World Health Organization, World health report 2002,

向井 苑生

Sonoyo Mukai

way changed over the years. Suspended particles，andReducing risks, promoting healthy life. Geneva, 2002.

especially submicron particles，combined with secondary[2] World Health Organization Regional Ofﬁce for Europe, Air

京都大学理学士，同大学院博士課程修了（宇宙物理学専攻），理学博士。

pollutants such as oxides of nitrogen and ozone，havequality guidelines for Europe, Copenhagen, 1987, WHO

元金沢工業大学教授，元近畿大学理工学部教授，元日本リモートセン

Regional Publications, European Series, No. 23.

シング学会理事，研究会会長，現評議員，元日本エアロゾル学会監事，

become a major problem in the large urban areas aroundthe world. At the same time，the populations of the rapidly[3] World Health Organization Regional Ofﬁce for Europe, Air

expanding megacities of Asia，Africa and Latin America are

quality guideline for Europe, 2nd ed. Copenhagen, 2000,

increasingly exposed to levels of ambient air pollution that

WHO Regional Publications, European Series, No. 91.

京都情報大学院大学教授。

常任理事，日本学術振興会専門委員。

rival and often exceed those experienced in industrializedcountries in the ﬁrst half of the twentieth century [7].
In general，the highest concentrations of PM10 werereported from Asia. This region also experiences relatively

The highest concentrations of PM10 are found in Africa，high background concentrations owing to forest fires andAsia and Latin America. Trends in air quality development

local emissions of particles from the use of poor-quality

differ in respect of the indicator pollutants. In Europe，

fuels. A well-known springtime meteorological phenomenon

PM10 levels had decreased by the end of last century but

throughout East Asia，causing the Asian dust，originateshave tended to rise again，which may be partially explained

from windblown dust from the arid region of Mongolia andby changing weather conditions. Even though large Asian

コラム

次のスーパームーンは？

いつごろだれが言い出したのか知らないが，今や普通名詞

り返すと，公転はｙ＝1.071714ｘ回である。それをExcelで簡になっている。天文学用語ではなく多分占い用語だろう。スー

単に計算してｘ，ｙが整数である最も簡単な組み合わせとし

パームーンとは満月と近地点通過が同じ日（何時間以内かはて x=14 y=15 が見つかる。すなわち1.071714に近い既約分

知らない）に起こることをいうそうだ。月はかなり扁平な公数は15 ／ 14ということで，月は満ち欠けを14回繰り返す間

China and adds to the general level of PM in the region.

転軌道を描き，その離心率は0.05もある。地球に最も近い時に地球の周りを15回公転する。スーパームーンは14 朔 望 月≒

cities have seen a slightly reduction in PM10 levels over

Chinese cities experience very high airborne particleの距離（近地点距離）と最も遠い時の距離（遠地点距離）の

1年1ケ月17日または18日ごとに起こることがわかる。ただし

the last few decades，PM10 and PM2.5 is still the major air

concentrations due to primary particles emitted from coal比は（1＋0.05）／（1－ 0.05）＝1.105

この計算は長期間続けているとズレが生じるのでご注意。

pollutant in Asia. Many of the large cities in Latin America，and biomass combustion and motor vehicle exhaust，as

サイズは通常時の5％増，最小時の10%増である。去年の8月

as well as Mexico City，still experience high levels of PM.

well as secondary sulfates formed by atmospheric chemical

10日に起こったが次はいつ起こるのだろうか？

でスーパームーンのAir pollution in megacities around the world has beenreaction from the sulfur dioxide emitted when coal is

an issue for several years. There were 24 megacities eachburned. PM2.5，whose diameter is 2.5 μ m or less is anwith more than 10 million inhabitants. Twelve of theseimportant indicator of risk to health from particulate

megacities are located in Asia，four in Latin America

pollution，and might also be a better indicator than PM10

and two in Africa: Cairo in Egypt and Lagos in Nigeria.

for anthropogenic suspended particles in many areas.

転のためだ。この数値の比は1.071714，すなわち満月から次According to the World Bank some African cities are growing

High PM2.5 readings will cause a spike in the mortalityの満月までに月は1.071714回公転するわけで，朔望をｘ回繰

by more than 10% annually. In many megacities，such asrate of patients suffering from heart and lung diseases.

月の満ち欠けの周期は朔望月＝29.54日で，月の公転周期は
近点月＝27.554日，満月から次の満月までの期間は月が地球の周りを１周する期間より約2日長い。その違いは地球の公

昨 年 8 月10日より14 朔望月後は今年9月28日である。正確には10時 46 分に近地点通過（35万 6877 km）で，11時51分に満月となる。ちなみに中秋の名月は旧暦の 8月15日で今年は満月の前日9月27日である。
なお，その次のスーパームーンは2016年11月14日に起こる。
ということで実はありふれた現象なのだ。

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