Toxic effects of air pollution and it’s mitigation by urban

vegetation

Jo Cavanagh

Health effects of air pollution

• Respiratory effects –– Impaired lung function (developmental effects

in children) – Asthma incidence

– Chronic obstructive pulmonary disease (e.g. chronic bronchitis, emphysema)

• Cancer• Cardiovascular disease

Investigation of health effects

• Epidemiology– Study of population effects

• Toxicology– Study of mechanisms of effects

– Role of different physico-chemical properties of particulates

Sites of First Contact

LungTransition metals (eg Fe, Ni, V) Carbon coreOrganics

Lung lining

Blood

Epithelial cells

Unmodified

Alveolar macrophage

ModifiedAnti-oxidant rich

Cytokine induction

How do we do it??

Filter

PM10 collection Extraction

Soxhlet extraction GC-MS analysis

Analysis

What are we looking at?…..

• Carcinogenic potential (organic fraction)– Dioxin-like activity

– mutagenicity

• Inflammatory potential (primarily soluble (metals) fraction)– Inflammatory markers (IL-6, TNF-a)

– cytoxicity

Some preliminary results…….ambient air

samples

Auckland – dioxin-like activity (/m3)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

1 2 3 4 5 6 7 8

Date

ER

OD

pg/

m3

0

5

10

15

20

25

30

Par

ticul

ate

conc

entr

atio

n (u

g/m

3)

EROD Particulate concentration

5/061/03 24/0428/0319/03 23/072/0730/05

Christchurch - dioxin-like activity (/ m3)

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

450.0

500.0

1 2 3 4 5 6 7 8 9 10 11

Date

ER

OD

act

ivity

pg

/m3

0

20

40

60

80

100

120

140

part

icul

ate

conc

entr

atio

n (u

g/m

3)

PM2.5 PM10 PM10 concentration PM2.5 concentration

7/065/03 28/044/0423/0317/03 16/0612/061/06 28/0623/06

Christchurch - inflammatory activity (water soluble fraction, / m3)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

1 2 3 4 5 6 7 8 9 10 11

Date

TN

F-a

(pg/

m3)

0

20

40

60

80

100

120

140

Par

ticu

late

con

cent

rati

on (u

g/m

3)

TNF-a PM10 TNF-a PM2.5 PM10 PM2.5

7/065/03 28/044/0423/0317/03 16/0612/061/06 28/0623/06

Auckland - inflammatory activity (water soluble fraction, / m3)

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

1 2 3 4 5 6 7 8

Date

TN

F-a

(pg

/m3)

0

5

10

15

20

25

30

TNF-a

PM10

5/061/03 24/0428/0319/03 23/072/0730/05

Mitigation of air pollution

• Policy options– Warm homes initiatives

– Vehicles emissions testing– Vehicle maintenance

• Technological solutions– Improved fuel quality/alternative fuel types

– Engine efficiency/catalysts

• Urban vegetation

Significance of urban vegetation

• Estimated health benefit of £900,000 for Britain

• Saving of 140 lives by doubling the number of trees planted in the West Midlands, UK

• Removal of 234 t of particulates annually from Chicago’s air

• Preliminary estimates indicate1320 t PM10, 2740t NO2 removed by trees in Auckland

Processes for pollutant removal

Roadside vegetation

• Already has a number of purposes– Visual amenity

– Road run-off control/treatment– Visual aid to enhance road safety

• Few (no) studies have investigated the efficacy of roadside vegetation in enhancing air quality

Evidence for mitigation effects

• Dust accumulation on leaves of trees close to roadways

• Increased concentrations of contaminants in soil underneath roadside vegetation

• Increased concentrations of contaminants in leaves of trees close to roadways

Vegetation ‘structure’

• Hedge

Vegetation structure

• Hedge• Landscaped

Vegetation ‘structure’

• Hedge• Landscaped• Overhanging trees – median strip

• Overhanging trees – roadside

Factors influencing mitigation potential

• Dispersion of pollutants from roadways• Vegetation ‘structure’

– leaf surfaces– proximity to roadway

– height of vegetation

• Empirical data/modelling– ENVI-met (microscale climate model, UC)

Roadside distribution of particulates

Deposition from roadways

Riccarton bush (UC)

Summary

• Organic fraction of ambient air particulates demonstrate carcinogenic potential

• Water-soluble fraction of ambient air particulates demonstrate inflammatory potential

• Urban vegetation, including roadside vegetation, demonstrate potential for mitigation of particulate air pollution