sources, composition and health impacts of airborne particulate matter roy m. harrison university of...
DESCRIPTION
PRIMARY AND SECONDARY PARTICLES Primary particles are those emitted directly from a source Secondary particles are those formed in the atmosphere from chemical reactions o sulphates from sulphur dioxide oxidation o nitrates from oxidation of oxides of nitrogen o secondary organic aerosol from oxidation of volatile organic compoundsTRANSCRIPT
SOURCES, COMPOSITION AND HEALTH IMPACTS OF AIRBORNE PARTICULATE MATTER
Roy M. HarrisonUniversity of Birmingham
and UK National Centre for Atmospheric Science
United Kingdom
CONTENT
A few definitions Sources of particles Chemical composition, and what it tells us Implications for human health
PRIMARY AND SECONDARY PARTICLES
Primary particles are those emitted directly from a source
Secondary particles are those formed in the atmosphere from chemical reactionso sulphates from sulphur dioxide oxidationo nitrates from oxidation of oxides of nitrogeno secondary organic aerosol from oxidation of
volatile organic compounds
DEFINITION OF TERMINOLOGYAirborne particles are measured as:
o PM10 – approximates to particles less than 10 micrometres diameter, measured by weighing (µg m-3)
o PM2.5 – less than 2.5 micrometres diameter (known as fine particles) (µg m-3)
o PM10 minus PM2.5 – coarse particles (µg m-3)
o Nanoparticles (ultrafine) – less than 0.1 µm diameter, usually evaluated by counting (# cm-3)
Total PM2.5 emissions (kt), 1990-2009, 2015 and 2020
PM10-Overall (BCCS)
Iron-rich Dusts13.4%
NaCl9.3%
NH4NO3/NaNO318.5%
Carbonaceous Material31.7%
Other3.7%
(NH4)2SO416.0%
Calcium Salts7.4%
PM2.5-Overall (BCCS)
NaCl4.0%
Iron-rich Dusts5.9% Calcium Salts
2.5%
NH4NO3/NaNO321.2%
Carbonaceous Material37.3%
Other5.2%
(NH4)2SO424.0%
PM10 - Episode (BCCS)
NaCl2.6%
Calcium Salts3.8%
Iron-rich Dusts14.3%
Carbonaceous Material22.0%
(NH4)2SO418.2%
NH4NO3/NaNO339.0%
PM2.5-Episode (BCCS)
NaCl1.7%
Calcium Salts1.0%
Iron-rich Dusts6.3%
Carbonaceous Material22.6%
(NH4)2SO422.7%
NH4NO3/NaNO345.8%
(a)
(b)
RECEPTOR MODELLING Use of air quality data to infer the sources responsible for measured
pollution levels (opposite of dispersion modelling!)
Receptor modelling of airborne particles depends upon an assumption of mass conservation
Ci =
where Ci = airborne concentration of component, i= mass fraction of component i in particles from source, j= mass of particles from source j in an air sample
Analysis of many air samples for multiple chemical components is necessary
TYPES OF RECEPTOR MODELLING OF PARTICULATE MATTERThere are two main types• Chemical Mass Balance
- Requires only one air sample, although better results are obtained with more
- Requires knowledge of chemical composition of particles from each source ( )
- Varies for all chemical components to obtain best fit to mass conservation equation
• Multivariate Statistical- Principal Component Analysis widely used, but Positive Matrix
Factorization (PMF) has advantages and is more frequently utilised- Requires no advance knowledge of source chemical composition- Requires many separate samples, and identifies temporal
correlations of components (e.g. Na and Cl in sea salt) in a multidimensional space.
RECEPTOR MODELLING WITH CMB MODEL
Uses organic molecular markers and trace elements to apportion the carbonaceous component of PM2.5
Source apportionment of the entire PM2.5 is conducted using the Pragmatic Mass Closure Model
Results have been processed for winter air samples collected at LNK and HAR
NK Site During ClearfLo (1)
Daily PM2.5 Source Contribution Estimates with Secondary Biogenic Components at NK
Daily PM2.5 Source Contribution Estimates at HAR
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
Jan-
12Ja
n-13
Jan-
14Ja
n-15
Jan-
16Ja
n-17
Jan-
18Ja
n-19
Jan-
20Ja
n-21
Jan-
22Ja
n-23
Jan-
24Ja
n-25
Jan-
26Ja
n-27
Jan-
28Ja
n-29
Jan-
30Ja
n-31
Feb-
01Fe
b-02
Feb-
03Fe
b-04
Feb-
05Fe
b-06
Feb-
07Fe
b-08
Ove
rall
PM2.
5 C
ontr
ibut
ion
( mg
m -3
)
HAR
Other
AmmoniumNitrateAmmoniumSulphateSeaSalt
Other OM
Total Traffic
FoodCookingCoalCombustionDust/Soil
Natural Gas
Woodsmoke
VegetativeDetritusMeasuredPM2.5
SELECTED MEAN CONTRIBUTION TO PM2.5 MASS, µg m-3 (%)
How do we know that particles cause adverse health effects?
How large are those effects?
Air Pollution EpidemiologyCurrent understanding of the effects of air pollution on humanpopulations is mainly from:
• time series studies, which relate day-to-day changes in air pollutant concentrations to mortality and hospital admissions. Such studies inform us about the effects of short-term (24-hour) exposures to particles and other air pollutants.
• cohort studies, which relate long-term air pollutant concentrations in different cities to rates of death and causes of death (disease type).
Results of the Cohort StudiesThere have been few cohort studies of air pollution effects. Twohave been especially comprehensive and influential.
• The Harvard Six Cities Study, which showed a relationship between average concentrations of particulate matter and death rates (controlled for other risk factors) in six US cities. The study examined effects of both PM10 and PM2.5 and found a closer relationship with mortality for PM2.5.
• The American Cancer Society Study showed a relationship between PM2.5 and death rates for cardiovascular disease, respiratory disease and lung cancer in 50 US cities.
Adjusted Mortality Relative Risk (RR) Associated with a 10 µg/m3 Change in Fine Particles Measuring Less than 2.5 µm in Diameter
Adjusted RR (95% CI)* Cause of Mortality 1979-1983 1999-2000 Average All-cause 1.04 (1.01-1.08) 1.06 (1.02-1.10) 1.06 (1.02-1.11)
Cardiopulmonary 1.06 (1.02-1.10) 1.08 (1.02-1.14) 1.09 (1.03-1.16)
Lung cancer 1.08 (1.01-1.16) 1.13 (1.04-1.22) 1.14 (1.04-1.23)
All other causes 1.01 (0.97-1.05) 1.01 (0.97-1.06) 1.01 (0.95-1.06)
*Estimated and adjusted based on the baseline random-effects Cox proportional hazards model, controlling for age, sex, race, smoking, education, marital status, body mass, alcohol consumption, occupational exposure, and diet. CI indicates confidence interval. Source: Pope et al. (2002)
ESTIMATE OF EFFECT OF CHRONIC PARTICULATE MATTER EXPOSURE UPON MORTALITY
“The current (2008) burden of anthropogenic particulate matter is, with some simplifying assumptions, an effect on mortality in 2008 equivalent to nearly 29,000 deaths in the UK at typical ages and an associated loss of total population life of 340,000 life-years. The burden can also be represented as a loss of life expectancy from birth of approximately 6 months”.
Health Protection Agency (2010)
CHRONIC EFFECTS(LONG-TERM EXPOSURE)
Burden of disease attributable to 20 leading risk factors in 2010, expressed as a percentage of global disability-adjusted life-years for both sexes
What do I mean by ultrafine particles?
It is particles with one dimension < 100 nm, but either
o measured by mass (usually referring to an aerodynamic diameter) – PM0.1
o measured by number (usually referring to a mobility diameter)
PARTICLE SIZEDISTRIBUTIONMEASURED IN BIRMINGHAM
Particle Number, Surface Area and Mass
Measuring:Particle number reflects particles < 100
nanometres primarily
Particle surface area reflects mainly particles of 50-1000 nm
Particle mass reflects particles of > 100 nanometres (usually to 2.5 µm or 10 µm)
Complete Dataset UNECE-EuropeTransport sector contributes about 75% to PN emissions
Source: Hugo Denier van der Gon
Spatial distribution
Source: Hugo Denier van der Gon
SHORT TERM (ACUTE) EFFECTS- Elucidated through the “time series” epidemiological studies
which relate day-to-day changes in air pollutant concentrations with changes in daily mortality and hospital admissions, frequently with a lag of up to three days between cause and effect.
- Department of Health Committee on the Medical Effects of Air Pollutants (COMEAP) has made quantification estimates of mortality and hospital admissions resultant from exposure to PM10, sulphur dioxide, nitrogen dioxide and ozone.
- Biggest uncertainty is attached to who is dying prematurely and the extent of loss of life expectancy.
Richard Atkinson and Ross Anderson (St. George’s Hospital Medical School) used case-crossover time series methodology to estimate the percentage increase in a given health outcome corresponding to the inter-quartile range (75%ile minus 25%ile) of concentration for several particle metrics
London Epidemiological Study
Urban Ambient Particle Metrics and Health: A Time Series Analysis, R.W. Atkinson, G.W. Fuller, H.R. Anderson, R.M. Harrison and B. Armstrong, Epidemiology, 21, 501-511 (2010).
Respiratory Mortality (lag 2)(Graph shows % change between 25%ile
and 75%ile concentration and 95% CI)-2
02
46
8%
(95%
CI)
PNCNO3 CL
SO4 BS
GR PM10
NK PM10
PM10
GR PM25
PM25
GR PM10
2.5PRI10
NONP10
NONP2.5
NONP102.5
-20
24
68
% (9
5% C
I)
PNCNO3 CL
SO4 BS
GR PM10
NK PM10
PM10
GR PM25
PM25
GR PM10
2.5PRI10
NONP10
NONP2.5
NONP102.5
Cardiovascular Mortality (lag 1)(Graph shows % change between 25%ile
and 75%ile concentration and 95% CI)
-20
24
6%
(95%
CI)
PNCNO3 CL
SO4 BS
GR PM10
NK PM10
PM10
GR PM25
PM25
GR PM10
2.5PRI10
NONP10
NONP2.5
NONP102.5
-20
24
6%
(95%
CI)
PNCNO3 CL
SO4 BS
GR PM10
NK PM10
PM10
GR PM25
PM25
GR PM10
2.5PRI10
NONP10
NONP2.5
NONP102.5
CONCLUSIONS Airborne particles in the UK have complex chemical
composition reflecting a mix of primary and secondary sources.
Poorly quantified and little regulated sources contribute significant to particulate matter mass.
Fuel combustion sources dominate the ultrafine particle fraction, with sulphur content being crucial.
Airborne particle exposure has a major impact upon morbidity and mortality in the UK.
There is some, limited, evidence that ultrafine particles are primarily responsible for effects upon cardiovascular health outcomes, with larger particles causing respiratory effects.
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