uk air quality indicators

UK Air Quality Indicators

Janet DixonAir and Environment Quality Division, Department of Environment, food and

Rural Affairs, UK

Air quality monitoring network

UK Air Pollution Index• Used for providing a public summary of current and forecast air pollution• 1-10 scale in 4 bands for 5 pollutants - ozone, PM10, SO2, NO2, CO• Produced for all 16 UK zones and largest 16 of the 28 UK agglomerations• Levels reported = highest for any single pollutant• Has health advice associated with each band• Mainly driven by PM10 and O3

• Further information: www.airquality.co.uk/archive/standards.php#band

UK Air Pollution IndexO3 NO2 PM10 SO2 CO

µg m-3 (mg m-3 for CO)

8hr running mean or hourly mean

Hourly mean 24 hour running mean

15 minute mean

8 hour running mean

Low(1-3)

0 – 99 0 - 286 0 – 49 0 – 265 0 – 11.5

Moderate (4-6)

100 – 179 287 – 572 50 – 74 266 – 531 11.5 – 17.3

High(7-9)

180 – 359 573 – 763 75 – 99 532 – 1063

17.4 – 23.1

Very high (10)

> 360 > 764 > 100 > 1063 > 23.2

UK Air Quality Headline Indicator

• UK Sustainable Development Strategy • One of 15 headline indicators• Developed in 1998, reviewed in 2002• Captures ‘acute’ air quality issues• Counts number of days of moderate or higher (from AP Index)

pollution for 5 ‘acute’ pollutants – ozone, PM10, SO2, NO2, CO• Does not correspond directly to UK Air Quality Strategy

objectives

Headline indicator

• Maximum number of sites used is fixed • Pre-1998 – up to 34 urban and 14 rural/remote• 1998 – 34 urban and 14 rural/remote• 2002 – 49 urban and 16 rural/remote

• To be included sites need minimum range of pollutants and data capture (>75%)• Rural – at least O3

• Roadside/kerbside – at least PM10

• Other urban – at least O3, PM10 and SO2

• Fairly robust to changes in network• Urban sites cover 26 of the 28 UK agglomerations

0

10

20

30

40

50

60

70

1987 1989 1991 1993 1995 1997 1999 2001 2003

Days when air pollution is moderate or higher: 1987-2003

Urban sites

Rural sites

Final 2003 indicator

0

10

20

30

40

50

60

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Causes of air pollution at urban sites

total urban

0

10

20

30

40

50

60

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

particles

sulphur dioxide

Causes of air pollution at urban sites

total urban

0

10

20

30

40

50

60

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

ozone

particles

sulphur dioxide

Causes of air pollution at urban sites

total urban

The main episodes driving 2003

• Exceptionally hot summer – • high ozone

• Particulate episodes in spring, including • UK and European element• Saharan dust storm

9

10

11

12

13

14

15

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

Sum

mer

Tem

pera

ture

0

10

20

30

40

50

60

70

80

Ozo

ne D

ays

Urban

Rural

• high secondary particulates (SO2 & NO2 gas converted to particulate sulphates & nitrates)

0

5

10

15

20

25

30

35

40

45

50

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003Year

Con

cent

ratio

ns (

m g/m

3)

AverageRange

40 ug/m3 objective20 ug/m3 prov. objective

PM100

10

20

30

40

50

60

70

80

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003Year

Con

cent

ratio

ns (

m g/m

3 )

Average

Range

40 ug/m3 objective NO2

0

10

20

30

40

50

60

70

80

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003Year

Con

cent

ratio

ns (

m g/m

3 )

Average

Range

20 ug/m3 vegetationprotection

SO2

•Indicator picks up peaks – what about long-term trends?

but….

….for ozone:

0

10

20

30

40

50

60

70

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Year

Conc

entra

tions

(m g/m

3)

Average

Range

• 2003 was an exceptional year.• Headline Indicator accurately reflects poor air

quality in 2003 (but not every aspect).• Headline indicator is currently being reviewedFor the future:

Conclusions

long-term trend downwards for most pollutants.

ozone increasing - global ozone precursor emissions, (?) global warming