Evaluation of mortality changes associated with reduced wood smoke air pollution in Launceston, Australia

Fay Johnston, Menzies Institute for Medical Research, University of Tasmania

Ivan Hanigan, University of Tasmania

Sarah Henderson, British Columbia Center for Disease Control

Geoff Morgan, University of Sydney

Overview

• Background

• Air quality interventions

• The mortality evaluation

• Results

• Policy implications

Tasmania

Compared with the rest of Australia….

• Poorer

• Older

• Worse health

• More rural • more than half the live in small

rural towns

• More wood heating • Overall 30%

• 50% in smaller towns.

Launceston’s air quality and community responses 1990-2007

Problem identified

• Peak wood heater use • High community concern

Initial Responses

• Air Quality characterised in detail • Winter air quality forecasts • Planning of interventions

1990s 1994-2001 2001-2007

Coordinated Action

• Woodheater replacement program • Education and enforcement

Air pollution (PM10) in Launceston, 1994-2007

We compared mortality before and after the intervention

In central Launceston where the intervention took place (pop 66,000)

and

Central Hobart where there were no interventions (pop 147,000)

Exposure • Period of improved air quality (6 ½ years from July 2001) was

compared with the 6 ½ years before July 2001

Outcomes • Percent change in daily standardised all-cause, cardiovascular and

respiratory mortality

Analysis • Poisson time series regression adjusted for:

• Population age structure,

• influenza epidemics

• daily and lagged temperature and humidity

• day of week

• secular mortality trends in the rest of Tasmania - 150 day moving average of standardised daily mortality

Approach

Results – small numbers to work with

Mortality Annual

total Annual male

Annual female

Winter (male+female)

All cause 595 284 311 158

Cardiovascular 237 107 130 68

Respiratory 54 27 28 17

Mean annual number of deaths from all-causes, cardiovascular, and respiratory conditions in Launceston1994-2007

All-cause mortality and PM10, Launceston, 1994-2007

-30

-20

-10

0

10

20

30

40

Perc

ent

change

All-cause Cardiovascular Respiratory

Launceston

Hobart

-40

-30

-20

-10

0

10

20

30

Annual mortality

Winter mortality

Perc

ent

change

Mortality changes in Launceston and Hobart

Perc

ent

change

Launceston

Hobart

Annual mortality

Winter mortality

Perc

ent

change

Mortality changes in Launceston and Hobart - MALE

-40

-30

-20

-10

0

10

20

30

All-cause Cardiovascular Respiratory

-40

-30

-20

-10

0

10

20

30

Perc

ent

change

Launceston

Hobart

Annual mortality

Winter mortality

Perc

ent

change

Mortality changes in Launceston and Hobart - FEMALE

-40

-30

-20

-10

0

10

20

30

-30

-20

-10

0

10

20

30

40

All-cause Cardiovascular Respiratory

Mortality changes, Launceston and Hobart by age-group

Launceston

Hobart

-30

-20

-10

0

10

20

30

Age 60-74 years

Age 75+ years

-40

-30

-20

-10

0

10

20

30

All-cause Cardiovascular Respiratory

Perc

ent

change

Perc

ent

change

Sensitivity analyses

• Results robust to • Start date of ‘period of improved air quality’

• Definition of influenza epidemics

• Methods for age standardisation

• Modelling of metrological variables

• Results were sensitive to how we derived the secular trend from data for the rest of Tasmania

Sensitivity analysis: the influence of smoothing the data for secular long term and seasonal trends

all cause cardiovascular respiratory

Conclusions

• Coordinated interventions led to large sustained AQ improvement

• Improved AQ was associated with reduced mortality in Launceston but not in Hobart • Association clearest in men, especially 60 to 75 year age group • Trend towards reduced winter cardiovascular and respiratory mortality

Tasmania

• The local case study was influential – biomass smoke top priority in Australia’s most recent National Air Strategy

• Removing wood as a heating source was effective but is not widely supported • Wood heater use is increasing and many regret changing to electricity

• Renewable – forest resource

• How to reduce emissions? • Improve user technique

• Tighter emissions standards

• Simple technology

Implications for policy - Australian perspective

Implications for policy

• Longer term • Subsidise ultra-efficient - foolproof biomass

heaters

• Combine with forest and fire management

• Shorter term - strengthen regulation and health protection • Resource local councils / EPAs

• Better public education

• Better use of evidence-based interventions • Portable air cleaners

Thank you Hosts

• BC Lung Association

• Ryan Allen

Funding agencies • Australian Research Council

• Department of Health and Human Services Tasmania

Advice on original paper • Mark Clements

• Doug Dockery

• John Todd

• Mike Power

• John Innis

• EPA Tasmania

Model

log(Oij) = Period + Agej + Ti + Ti-2 + Hi + Hi-2 + DOWi + Flui + SecularTrend +

offset(log(Popij)) Oij = observed number of cases on dayi in Agej;

Period = indicator variable for pre- and post-intervention periods;

Age = age groups by 15 year intervals to age 74, then 5 year intervals to 84, and ages 85 years and older;

Ti = daily mean temperature (°C); T i -2 = average of 3-day lagged temperature dayi (°C);

Hi = daily mean dew point (°C); Hi-2 = average of 3-day lagged dew point (°C);

Flu = indicator variable for days when the 14-day moving average of deaths for influenza and pneumonia in Tasmania exceeded the 95th percentile;

SecularTrend = the 150-day moving average of the daily directly standardised cause-specific mortality rates for Tasmania (excluding the intervention population of Launceston);

Popij = interpolated population on dayi in Agej.

Model comparisons

Annual deaths per 100,000 people

1994-2000 2001-2007 Percent decrease

All Tasmania All-causes 833 712 14.61

Cardiovascular 373 265 28.91

Respiratory 78 62 20.50

Launceston All-cause 857 742 13.45

Cardiovascular 388 274 29.53

Respiratory 86 064 24.63

Hobart All-cause 825 722 12.48

Cardiovascular 358 268 25.18

Respiratory 76 64 15.73

Mortality in Tasmania 1994-200 and 2001-2007