[PDF] - Polyarom atic hydrocarbons ( PAHs) John W atterson ( w ith thanks PDF Document

SLIDE 1

1 Polyarom atic hydrocarbons ( PAHs) John W atterson

( w ith thanks to Peter Colem an, Chris Conolly, Mike W oodfield, Chris Dore and Geoff Dollard)

W hat’s in this presentation

What are PAHs
EU Directive
UK position
Important sources of PAHs in the UK
Atmospheric fate and transport
Health effects of PAHs
Measurements networks and current

concentrations in air

Data in the NAEI and NAQIA

SLIDE 2

2 W hat are PAHs?

They are polyaromatic hydrocarbons
Polyaromatic hydrocarbons consist of

– two or more fused benzene rings – in linear, cluster or angular arrangements

…

and contain only carbon and hydrogen

Why worry about them?

W hy w orry about PAHs?

Ubiquitous, as

– formed during combustion of fossil fuels

Some are probable or possible

human carcinogens

– International Agency for Research on Cancer (IARC) Group 2A: The agent (mixture) is probably carcinogenic to humans, e.g. – Benzo[ a] pyrene (BaP), Benz[ a] anthracene

SLIDE 3

3 Groupings and classifications - w hich PAHs should w e m easure?

There are lots of PAHs!
There is no internationally recognised suite
f PAHs to assess in air

– List frequently encountered is US ‘EPA 16’ – In some international fora, the ‘Borneff 6’ is used – Within the UNECE POPs protocol the four least volatile of the ‘Borneff 6’ compounds are reported

Som e im portant PAHs - physical and chem ical properties

Benzo[ a] pyrene ( BaP)

Benzo[ def] chrysene 3,4-Benzopyrene 6,7-Benzopyrene 1,2-Benzpyrene 4,5-Benzpyrene

Molecular form ula:

C20H12

CAS Registry No.:

50-32-8

Boiling point ° C:

496

Melting point ° C:

178.1

Vapour Pressure ( Pa at 2 5 ° C) 7.0 x 10-7

[ 1]

SLIDE 4

4 EU policy fram ew ork ( this drives UK policy)

Air Quality Framework Directive 96/ 62/ EC,

which now has several Daughter Directives – lists pollutants for which limit values are to be set – sets out framework to manage AQ

assessment of AQ
monitoring methods and networks
plans and programmes to improve AQ
reporting to Commission
informing the public of current AQ

Daughter directives

1999/ 30/ EC

– NOx, SO2, Particulate Matter (PM 10), lead

2000/ 69/ EC

– CO and benzene

3rd Daughter Directive

– ozone

SLIDE 5

5 4 th Daughter Directive

4th Daughter Directive

– proposal under preparation – arsenic, cadmium, nickel, mercury (possibly) – and PAH – BaP going to be used as a marker – metals and PAH to be in separate directives ??? Not finally decided yet

Lim it values currently being proposed in 4 th Daughter Directive

BaP

1 ng/ m³ excess risk 1: 10-4 (possible threshold)

As

6 ng/ m³ excess risk 1: 10-5 (possible threshold)

Cd

5 ng/ m³ excess risk 1: 10-5 (confounding by As)

Ni

20 ng/ m³ excess risk 1: 10-5 (speciation )

Hg

50 ng/ m³ not going to be proposed

Note: lifetime excess risks

SLIDE 6

6 Excess Risk - w hat does this m ean and how is it used?

In this case, Excess Risk of lung cancer
WHO guidance suggests that the unit

risk of lung cancer is 87 x 10-6 per ng BaP per m 3 for lifetime exposure

In plain English, this means there is a

87 in a million chance of dying from lung cancer over a lifetime, from exposure to 1 ng per m 3 of BaP throughout your life

Excess Risk - how m uch risk is acceptable?

WHO has considered health based

evidence

View that the upper limit of the

additional lifetime risk should be less than 1 x 10-4

~ 1 x10- 6 per year is generally accepted

as the maximal risk level

The WHO uses 70 years as an average

lifetime ...

…

and so the maximum acceptable risk

ver a lifetime is 70 x ~ 1 x 10-6 = ~ 70

x 10-6

SLIDE 7

7 ~ 7 0 x 1 0 -6

( m axim um acceptable risk over a lifetim e)

8 7 x 10 -6 ( unit risk of lung cancer from BaP over a lifetim e)

Member States have variously set guideline or mandatory values of

between 0.1 and 1.3 ng BaP/ m 3

Since the risk has been evaluated on a lifetime exposure basis these

limits usually relate to a yearly average

Suggests a common air quality standard for BaP of less than 1.0

ng/ m 3, averaged over a yearly period

Now w e can calculate the acceptable am bient concentration

= ~ 1 ng per m 3

Risk and the public

Com parative

risks

SLIDE 8

8 Other relevant EU legislation

PAHs are covered by the Persistent

Organic Pollutant (POP’s) Protocol – under the United Nations Economic Commission for Europe’s Convention

n

– Long Range Transboundary Air Pollution [ UN ECE CLRTAP]

Under the Protocol, emissions of four

PAH compounds have to be reported annually

Persistent Organic Pollutant ( POP’s) Protocol

Protocol and emissions in the

future ...

– PAH in 2010 may not exceed the levels of 1990 (or any other base year between 1985 and 1995)

The Protocol will enter into force

after 16 ratifications

– which is expected between 2001 and 2002

SLIDE 9

9 Persistent Organic Pollutant ( POP’s) Protocol

The European Community is a party to the

Convention

Will therefore have to fulfil the obligations of

the Protocol after ratification

(Including the UK!)

European m em ber states am bient air PAH standards

Of EU member states currently only

Italy has legally enforceable ambient air standards for PAH

Five others have issued guidance for

planning and policy purposes

All have used BaP as a marker for PAH
Sweden has gone further and set a

value for fluoranthene as well.

SLIDE 10

10 Other EU legislation indirectly affecting PAH concentrations

Other Directives indirectly influence PAH

emission or concentration in ambient air – arising from the Auto Oil programme – on the incineration of wastes - the IPPC directive (96/ 61/ EC) – the air quality framework directive (96/ 62/ EC) – and its first daughter directive - 1999/ 30/ EC which addresses particulate matter

Daughter Directive 1 9 9 9/ 3 0/ EC

The objectives of 1999/ 30/ EC can not

be met – without the control of the emissions

f particulate material from a very

wide range of sources – many of which are sources of PAH as well

SLIDE 11

11 Vehicle em issions and W HO lim its

New vehicle emissions regulation ('EURO

IV') will, in time, further reduce particulate emissions and also PAH

The World Health Organisation [ WHO] has

examined the issue of PAH health risk on a number of occasions – published Air Quality Guidelines in 1987 and 2001

UK position on PAHs

The UK government continues to set

standards for pollutants in ambient air in order to protect human health

Recently, UK Expert Panel on Air Quality

Standards (EPAQS) (1999) issued a draft report

SLIDE 12

12 UK position on PAHs

EPAQS recommending that an annual

average concentration for benzo[ a] pyrene (BaP) in air as – 0.25 ng m -3 – would make the risk to human health from inhalation of PAHs insignificant

The EPAQS approach assumes that BaP

is a marker for the health effects of PAHs

Sources of PAHs in the UK

There are five major emission source

components – Domestic – Mobile – Industrial – Agricultural – Natural

Relative importance of these sources is

expected to change with time as a result of regulations and economic development

SLIDE 13

13 UK em issions of BaP ( kTonnes) from a range of sources

10 20 30 40 50 60 70 80 90 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Other Nature (Fires) Agriculture Road Transport Production Processes Residential Combustion

I ndustrial sources

Most important industrial sources

include – cokeries – primary aluminium production (in particular plants using the Soderberg process) – and wood preservation

Industrial sources are being increasingly

regulated (e.g. through I PPC); in addition improved energy management is leading to reduced/ improved combustion

SLIDE 14

14 I ndustrial sources

Total PAH emissions from industrial

sources are decreasing due to regulation (I PPC)

BaP from industrial sources is largely

associated with particles < 2.5 µm

Some industrial sources have

considerable impact on local air quality, even after applying BAT

Dom estic sources

Emissions are predominantly associated

with the combustion of solid fuels (as wood and coal)

BaP from domestic sources is associated

with a range of particle size including < 2.5 µm

Sources are numerous and widespread
There is no uniform European regulation
Improvements can be achieved using

new combustion appliances and fuel switching

SLIDE 15

15 A day in a city in the 1 9 5 0 s ... SO2 but also PAHs Unpredicted sources of PAH - Pyres from the foot and crisis

SLIDE 16

16

RESULTS - PAHs

Total emissions (kg) Napthalene 27,976 Acenapthene 1,441 Acenapthylene 1,794 Fluorene 272 Anthracene 208 Phenanthrene 1,794 Fluoranthene 593 Pyrene 448 Benz(a)anthracene 256 Chrysene 272 Benzo(b)fluoranthene 753 Benzo(k)fluoranthene 368 Benzo(a)pyrene 1,153 Dibenz(ah)anthracene 16 Ideno [1,2,3-cd]pyrene 432 Benzo(ghi)perylene 224 TOTAL PAH EMISSIONS 38,000 Total UK annual emissions (kg) 1,414,300 % of total annual emissions 2.69%

How m uch PAH w as released from the F&M crisis? Estim ates of NOx and PM 1 0 released

RESULTS - NOX

Total NOX emissions (kg)

472,613

Total NOX emissions (tonnes)

473

Total UK annual NOx emissions (tonnes)

1,885,696

% of UK total annual emissions

0.02506%

RESULTS - PM10

Total PM10 emissions (kg)

3,012,239

Total PM10 emissions (tonnes)

3,012

Total UK annual PM10 emissions (tonnes):

262,997

% of UK total annual PM10 emissions

1.145%

SLIDE 17

17 W hat happens to PAHs after they are em itted to air?

Atmospheric processing and transformation

– Physical and chemical removal processes, and wet and dry deposition are all important

Gas phase PAHs may undergo ...

– Daylight OH· (hydroxyl) reaction – Nightime Nitrate (NO3) reactions – Ozone reaction – Basic species with acids (formed from NOx & SOx) – Photolysis (UV)

emissions emissions e m i s s i

n

s e m i s s i

n

s

intake via food is major exposure route intake via food is major exposure route

deposition deposition

vapour / particle partitioning vapour / particle partitioning

reservoirs in sediment & soil reservoirs in sediment & soil bioconcentration in some fauna bioconcentration in some fauna

local and long range transport local and long range transport

deposition deposition

Fate and Transport of PAHs ( Sum m ary of Processes)

SLIDE 18

18 Size distribution of PAHs in air

PAH containing 5 or more rings

(including BaP) are found predominantly in the particulate phase

Those containing 2 or 3 rings are almost

entirely present in the vapour phase

4 ring compounds are particle-bound

but have the greatest seasonal variability between phases

The majority of particle-bound PAH is

found on small particles (< 2.5 µm)

Hum an exposure to PAHs

Human exposure to PAHs can occur via

several environmental pathways including – internal adsorption through eating charred food – inhalation of tobacco smoke – inhalation of ambient air – inhalation of indoor air – drinking water

SLIDE 19

19 Relative im portance of pathw ays & health effects

The relative importance of various routes to

human exposure will depend on – whether an individual smokes – where they live – the food preparation methods they use

The principal health effects that have been

associated with PAHs – are lung and bladder cancers – all exposure routes may increase the likelihood of bladder cancer, however inhalation is thought to be the major route to lung cancer

W hich pathw ays are im portant?

Food probably represents the largest exposure
f the whole body to PAHs
Smoking is an important exposure route

SLIDE 20

20 Locations for PAHs in the UK

Original network of four TOMPs sites

(London, Manchester, Middlesbrough and Stevenage) designed to provide information on long term trends of dioxins and PAHs

Two new sites added in 1996 in rural

areas (Hazelrigg and Stoke Ferry) to investigate the concentrations in rural locations.

Recent additions to the netw ork

Ten extra PAH monitoring sites have

been installed – some near industrial sites of types that were identified as significant sources of PAHs in a recent inventory – and others in an area of high domestic solid fuel use – and in a major urban area.

SLIDE 21

21

Modified

pesticide sampler with a PM10 inlet head (but impactor plates removed)

Flow rate

~ 5 m 3 per hour

PM10 inlet

PUF and filter cartridge (normally beneath inlet head) Flow control system

TOMPs sam pler used in the UK PAH sam plers at DEFRA, Ashdow n House, London

SLIDE 22

22 Germ an PAH sam pler Analytical m ethods for PAHs ( com plicated & expensive!)

Extraction for 8 hours with toluene

(glass distilled grade) in batches of four in a ‘Soxhlet’ apparatus

The analysis requires the use of a range
f techniques including

– gas chromatography coupled with high-resolution mass spectrometry – high pressure liquid chromatography – gas chromatography coupled with electron capture detectors

SLIDE 23

23 How ‘good’ are the m easurem ents likely to be - Uncertainty

There is no EN standardisation for the

quantification of PAH

Typical measurement uncertainty is + / -

50% at the 95% confidence level but many measurements will have considerably worse precision

Detection limit 0.02 to 0.05 ng/ m 3

Concentrations of BaP in the UK have fallen since the early 1 9 9 0 s

Mean annual atmospheric concentrations of Benzo(a)pyrene in urban areas (1991 to 1999)

0.01 0.1 1 10 100 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Date Atmospheric concentration (ng m-3) Cardiff (Urb) Glasgow (Urb) Lisburn (Urb) London 1 (Urb) London 2 (Urb) Manchester (Urb) Middlesbrough (Urb) Stevenage (Urb) BaP EPAQS standard

SLIDE 24

24 Concentrations around industrial sources can be high

Mean annual atmospheric concentrations of Benzo(a)pyrene in urban industrial areas (1991 to 1999)

0.01 0.1 1 10 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Date Atmospheric concentration (ng m-3) Ashington (Urb-Ind) Holyhead (Urb-Ind) Kinlochleven (Urb-Ind) Newport (Urb-Ind) Port Talbot (Urb-Ind) Scunthorpe (Urb-Ind) Bolsover (Ind) BaP EPAQS standard

Concentrations are seasonally variable - higher in w inter

Mean quarterly atmospheric concentrations of Benzo[a]pyrene in urban areas (1991 to 2000)

0.01 0.1 1 10 100 Jan-91 Jan-92 Dec-92 Dec-93 Dec-94 Dec-95 Dec-96 Dec-97 Dec-98 Dec-99 Dec-00 Dec-01 Dec-02 Dec-03 Date Atmospheric concentration (ng m-3) Cardiff (Urb) Glasgow (Urb) Lisburn (Urb) London 1 (Urb) London 2 (Urb) Manchester (Urb) Middlesbrough (Urb) Stevenage (Urb)

SLIDE 25

25 Typical EU concentrations of BaP

Data sparse
Data centre on concentrations of BaP
In the 1990's, typical annual mean levels for BaP in

rural background areas between 0.1 and 1 ng/ m 3; for urban areas between 0.5 and 3 ng/ m 3 (‘traffic’ sites are included at the upper part of this range)

up to 30 ng/ m 3 within the immediate vicinity of

certain industrial installations

Very few measurem ent data exist for rural

communities burning coal and wood dom estically; – however, these measurements suggest levels similar to those found in cities

Concentrations can be high close to large industrial

sites and busy roads

UK m apping of BaP to support policy

setting a provisional AQS for BaP
DEFRA have recently completed a piece of work

to help set an NAQS objective for BaP

The emission inventory for BaP is subject to

considerable uncertainty – emission measurem ents have been made both nationally and internationally and the relevant – activity statistics in some cases are not collected regularly – diffuse nature of some sources

This assessm ent suggested that by 2010

concentrations may be less than 0.25 ng m -3 at all sites with the exception of Lisburn and Scunthorpe

SLIDE 26

26 BaP m odelling and predictions Predicted level of exposure to BaP in the UK in 2 0 1 0

The area greater than the EPAQS

guideline of 0.25 ng m -3 may decline from – 1,562 km 2 (1999) – to 551 km 2 (2010)

The area with concentrations greater

than 1.0 ng m -3 is predicted to decline from – 20 km 2 (1999) – to 11 km 2 (2010)

The population weighted annual average

concentration is predicted to decline from 0.156 to 0.131 ng m -3.

SLIDE 27

27 W here to find data for your region

Air Quality Information

Emissions I nventory

http: / / www.aeat.co.uk/ netcen/ airqual/

E-m ail and ask!

W hat do LAs need to do

UK BaP objective provisional for the

present

Targets set should be for the longer

term

DEFRA have proposed a UK wide
bjective of achieving 0.25cng/ m 3 BaP

as an annual average by the end of 2010

This will not be a national standard
Neither will it be set in regulations for

the purposes of LAQM

SLIDE 28

28 Final com m ents on uncertainties - questions

How significant is the contribution of

traffic to PAH pollution? – 65% (Roy Harrison, based on receptor modelling) – 8% (DEFRA)

Which is the best PAH to use as a

marker for carcinogenicity?

Inventories are limited by lack of data