EFFECT OF SAHARAN DUST OUTBREAKS ON MIXING LAYER HEIGHT: IMPLICATIONS FOR AIR QUALITY AND HEALTH Pandolfi, M. 1 , Tobias, A. 1 , Alastuey, A. 1 , Sunyer, J. 2,3 , Schwartz, J. 4 , Lorente J. 5 , Pey, J. 1,6 and Querol, X. 1 1 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), c/ Jordi-Girona 18-26, 08034, Barcelona, Spain; 2 Centre for Research in Environmental Epidemiology (CREAL), c/ Doctor Aiguader 88, 08003, Barcelona, Spain; 3 Pompeu Fabra University, Plaça de la Mercè 10-12, 08002, Barcelona, Spain; 4 Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, 02115, Boston, MA, USA; 5 Department of Astronomy and Meteorology, University of Barcelona (UB), c/ Martí i Franquès 1, 08028, Barcelona, Spain 6 Aix-Marseille Université, CNRS, LCE FRE 3416, 13331 Marseille, France
1 Institute of Environmental Assessment and Water Research (IDAEA-CSIC), c/ Jordi-Girona 18-26, 08034, Barcelona, Spain;
2 Centre for Research in Environmental Epidemiology (CREAL), c/ Doctor Aiguader 88, 08003, Barcelona, Spain; 3 Pompeu Fabra University, Plaça de la Mercè 10-12, 08002, Barcelona, Spain;
4 Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, 02115, Boston, MA, USA; 5 Department of Astronomy and Meteorology, University of Barcelona (UB), c/ Martí i Franquès 1, 08028, Barcelona, Spain
6 Aix-Marseille Université, CNRS, LCE FRE 3416, 13331 Marseille, France
OUTLOOK
EFFECTS OF SAHARAN DUST OUTBREAKS ON MIXING LAYER HEIGHT RATIONALE OF THIS WORK
RESULTS
CONCLUSIONS
Less solar radiationreaching the surface thuslimiting the convectivegrowth of MLH
BARCELONA (NE SPAIN)
Pérez et al., ATMENV, 2004
EFFECTS OF SAHARAN DUST OUTBREAKS ON MIXING LAYER HEIGHT (1/3)
0
500
1000
1500
2000
2500
3000
290 300 310 320
Adapted from Pandolfi et al., STOTEN, 2014
EFFECTS OF SAHARAN DUST OUTBREAKS ON MIXING LAYER HEIGHT (2/3)
Alastuey et al., ATMENV, 2005
MLH
TENERIFE -CANARY ISLANDS (28.321 N, 16.381 W, 105 m.a.s.l.)
EFFECTS OF SAHARAN DUST OUTBREAKS ON MIXING LAYER HEIGHT (3/3)
EFFECTS OF SAHARAN DUST OUTBREAKS ON MIXING LAYER HEIGHT (MLH)
Alastuey et al., ATMENV, 2005
Pandolfi et al., ACP, 2013
Pandolfi et al., ACP, 2013
SAHARAN DUST OUTBREAK
ATLANTIC ADVECTION
1000 m
500 m100 m
BARCELONA (NE SPAIN)
Barcelona
Less solar radiationreaching the surface thuslimiting the convectivegrowth of MLH
BARCELONA (NE SPAIN)
Pérez et al., ATMENV, 2004
0
500
1000
1500
2000
2500
3000
290 300 310 320
Pandolfi et al., STOTEN, 2014
Alastuey et al., ATMENV, 2005
MLH
TENERIFE -CANARY ISLANDS (28.321 N, 16.381 W, 105 m.a.s.l.)
Perez et al., 2012Barcelona (NE Spain)
RATIONALE OF THIS WORK (1/1)
MLH represents the maximum volume of air at disposal for vertical dilution of pollutants at midday; The lower the MLH, the higher the concentration of local pollutants.
400
500
600
700
800
900
1000
1100
1200
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90
MLH
[m
a.s
.l.]
400
600
800
1000
1200
NAF>p90
20
30
40
50
60
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90 NAF>p9020
30
40
50
60
NO
2[m
gm-3
]
0
10
20
30
40
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90 NAF>p900
10
20
30
40
NO
[m
gm-3
]
0.2
0.3
0.4
0.5
0.6
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90
CO
[m
gm-3
]
0.2
0.3
0.4
0.5
0.6
NAF>p90
12000
14000
16000
18000
20000
22000
24000
26000
28000
30000
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p9012000
NAF>p90
16000
20000
24000
24000
nu
mb
er
[cm
-3]
10
15
20
25
30
35
40
45
50
55
60
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p9010
20
30
40
50
60
O3
[mgm
-3]
NAF>p90
%
%
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean%
%
0
10
20
30
40
0 1 2 3 4 5 6
mean
0
10
20
30
40
0 1 2 3 4 5 6
mean
0
10
20
30
40
0 1 2 3 4 5 6
mean
0
10
20
30
40
0 1 2 3 4 5 6
mean
0
10
20
30
40
0 1 2 3 4 5 6
mean
0
10
20
30
40
0 1 2 3 4 5 6
mean
-40
-30
-20
-10
00 1 2 3 4 5 6
mean
-40
-30
-20
-10
00 1 2 3 4 5 6
mean
%
• 2003 – 2010 • 2513 MLH (radiosounding at 12:00 UTC in Barcelona, NE Spain)
EFFECT OF MLH VARIATIONS ON AIR QUALITY DURING SAHARAN DUST OUTBREAKS (1/2)
0
15
30
45
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90 NAF>p900
15
45
30
PM
1[m
gm-3
]
0
10
20
30
40
50
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90 NAF>p900
10
20
30
40
50
PM
2.5
-10
[mgm
-3]
0
10
20
30
40
50
60
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90 NAF>p900
10
20
30
40
50
60P
M2
.5[m
gm-3
]
400
500
600
700
800
900
1000
1100
1200
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90
MLH
[m
a.s
.l.]
400
600
800
1000
1200
NAF>p90
0
10
20
30
40
50
60
70
80
90
100
ALL non-NAF NAF<p75 p75<NAF<p90 NAF>p90
µg
/m3
2003-2010 non-NAF NAF<p75 p75<NAF<p90 NAF>p900
20
40
60
80
100
PM
10[m
gm-3
]
Saharan dust
Local contribution
Local contribution > 35-50%
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
%
%
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
%
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
0
20
40
60
80
100
0 1 2 3 4 5 6
mean
mean
%
EFFECT OF MLH VARIATIONS ON AIR QUALITY DURING SAHARAN DUST OUTBREAKS (2/2)
10000
12000
14000
16000
18000
20000
22000
24000
26000
28000
30000
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
10000
20000
30000
#cm
-3<300
0.2
0.4
0.6
0.8
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <4500.2
MLH [m]
0.4
0.6
0.8
CO
[m
gm-3
]
0
10
20
30
40
50
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <3000
MLH [m]
10
20
30
40
50
NO
[m
gm-3
]
20
25
30
35
40
45
50
55
60
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <30020
MLH [m]
30
40
50
60
NO
2[m
gm-3
]
0
1
2
3
4
5
6
7
8
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <3000
MLH [m]
2
4
6
8
SO2
[mgm
-3]
0
10
20
30
40
50
60
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <3000
MLH [m]
10
20
30
40
50
60
O3
[mgm
-3]
non-dust days during the period 2003-2010 and analysis stratified by different heights of the mixing layer (<300m, <450m, <530m, <600m and <1000 m).
%
0
20
40
60
80
100
0 1 2 3 4 5 6 7
mean
%
0
20
40
60
80
100
0 1 2 3 4 5 6 7
mean
0
20
40
60
80
100
0 1 2 3 4 5 6 7
mean
0
20
40
60
80
100
0 1 2 3 4 5 6 7
mean
%
%
0
10
20
30
40
0 1 2 3 4 5 6 7
mean
0
10
20
30
40
0 1 2 3 4 5 6 7
mean
0
10
20
30
40
0 1 2 3 4 5 6 7
mean
0
10
20
30
40
0 1 2 3 4 5 6 7
mean
-50
-40
-30
-20
-10
00 1 2 3 4 5 6 7
mean
-50
-40
-30
-20
-10
00 1 2 3 4 5 6 7
mean
%
0
10
20
30
40
0 1 2 3 4 5 6 7
%
0
10
20
30
40
0 1 2 3 4 5 6 7
mean
0
10
20
30
40
50
60
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <3000
MLH [m]
10
20
30
40
50
60
O3
[mgm
-3]
EFFECT OF MLH VARIATIONS ON AIR QUALITY DURING NON-SAHARAN DAYS (1/2)
10
15
20
25
30
35
40
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <30010
MLH [m]
15
20
25
30
35
40
PM
2.5
[mgm
-3]
5
10
15
20
25
30
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <300
MLH [m]
5
10
15
20
25
30
PM
1[m
gm-3
]
0
5
10
15
20
25
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <3000
MLH [m]
5
10
15
20
25
PM
2.5
-10
[mgm
-3]
20
30
40
50
60
NoN-NAF <1000m <600 <530 <450 <300
µg
/m3
non-NAF <1000 <600 <530 <450 <30020
30
40
50
60
PM
10
[mgm
-3]
MLH [m]
%
%
%
%
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
0
10
20
30
0 1 2 3 4 5 6 7
mean
EFFECT OF MLH VARIATIONS ON AIR QUALITY DURING NON-SAHARAN DAYS (2/2)
-8
-6
-4
-2
0
2
4
6
8
0 200 400 600 800 1000 1200
MLH
PM10
IRR
[%
]
non-NAF days MLH [m]
< < < < <
-8
-6
-4
-2
0
2
4
6
8
0 200 400 600 800 1000 1200
MLH
PM10
IRR
[%
]
non-NAF days MLH [m]
< < < < <<200 <400 <600 <800 <1000
-1.3%
-3.6%
+1.2%
+3.2%
EFFECT OF MLH ON HEALTH AND PARTICLE TOXICITY DURING NON-SAHARAN DAYS (1/1)
-30
-20
-10
0
10
-6-30369
12
-4
0
4
8
12
16
-6
0
6
12
-10
0
10
20
IRR
[%]
IRR
[%
]IR
R [%
]IR
R [
%]
IRR
[%
]
MLH
PM1
PM2.5
PM2.5-10
PM10
-1.6%
+2.4%
-16%
+6%
+11%
non-NAF NAF<p75 P75<NAF<p90 NAF>p90
EFFECT OF MLH AND PM ON HEALTH DURING SAHARAN DUST OUTBREAKS (1/1)
CONCLUSIONS
The depth of ML is a key parameter for both AQ and health. It contributes to determine the degree of accumulation of local man-made pollutants and the lower the MLH the higher the concentration of pollutants
The thinning of ML makes more toxic the ambient air we breathe through a progressive accumulation of fine particulate matter, gaseous compounds and particle number of anthropogenic origin
The outbreaks of Saharan dust can cause a reduction of MLH with consequent accumulation of man-made local pollutants, thus contributing to the increased harmful effects on health of PM during NAF days observed in past studies The results put forward that other atmospheric components may have adverse health effects in urban environments and reflect the relevance of a synergic effect of atmospheric pollutants on health
In addition to a direct health effect of African dust, the observed increasing concentrations of local pollution with decreasing MLH may favor the formation of specific relevant PM species likely from condensation of accumulated gaseous precursors on the surface of dust particles and/or formation of new fine particles
The evidence that the same concentration of PM10 was less toxic on days with higher mixing layer heights may reflect lower toxicity of transported secondary particles than primary particles which predominate on low MLH days. It would be useful to apply the presented methodology to similar data from other Mediterranean cities to explore if and where the MLH is causing effects similar to those observed in Barcelona. Does the MLH reduce during NAF in other Mediterranean cities? Is there any effect of MLH on particle toxicity in other Mediterranean cities? Does the MLH thinning contribute to explain the differences observed in particle toxicity across the Mediterranean during Saharan dust outbreaks (different advection patterns and season from West to East)?
