concerns for health from smog and heat presentation to smog workshop for ontario medical officers of...
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Concerns for Health from Smog and Heat
Presentation to Smog Workshop
for Ontario Medical Officers of Health
Convened by Clean Air Partnership and
Ontario Medical Association
Dr. David McKeown
February 2006
• People can spend a lot of time close to pollution sources
Health Effects of Air Pollution
• More and longer lasting respiratory symptoms
• Reduced lung function • More bronchitis and
asthma attacks• More emergency room
visits• More lung cancer and
heart attacks• More hospitalizations &
early deaths
Burden of Illness Estimates – How Many People Are Affected?• Is a form of risk assessment• Applies risk coefficients from existing
epidemiological studies worldwide• Uses community-specific data on daily
pollution levels• Uses community-specific data on
adverse health outcomes such as hospitalizations and mortality (e.g. for respiratory and cardiac causes)
Air Pollution Burden of Illness – Toronto (2004)
• 1,700 premature deaths/year • 6,000 hospitalizations/year • Would likely not have occurred when
they did without exposure to air pollution• Preventable • Increases severity or frequency of
common medical conditions and illnesses• Created comprehensive agenda for
provincial action to improve air quality
Pyramid of Health EffectsToronto Annual Estimates for Inhalable Particulates
(PM10)
Premature mortality (acute)177
Cardiovascular hospitalization421
Respiratory hospitalizations597
Adult chronic bronchitis 1,186
Emergency room visits 5,981
Bronchitis in children
11,997
Asthma symptom days 71,930
Air pollution makes asthma worse
Comparison of Illness Estimates for Toronto from Air Pollution
InvestigatorYear
PublishedData
PeriodAnnual
MortalityAnnual
Hospitalization
TorontoPublicHealth
2004 1999 1,700 6,000
HealthCanada
20051998 to
20001,840 ----
OntarioMedicalAssociation
2005 2005 1,450 3,980
Air Quality Benefits Assessment Tool (AQBAT)
• Computer simulation tool developed by Health Canada
• Estimates human health benefits or impacts from changesin air quality
• Pollutants – CO, NO2, O3, SO2, PM2.5, PM10
• Health Endpoints
– Mortality (acute and chronic) – Acute respiratory symptom days – Chronic bronchitis – Cancer – Cardiac and respiration hospitalizations – Emergency room visits – Restricted activity days
Smog and Heat Problems Compounded in Cities
Urban Populations at Increased Risk
• Vehicles and people are in close proximity
• Canyon effect of buildings traps pollutants
• Urban heat island effect
• Roads contribute to heat retention in cities
• Local emissions compound transboundary pollution
• Elevated exposures during commuting (whether walking, cycling, waiting streetside for transit, or inside a vehicle in stagnant traffic)
Climate Change is Happening
• Green House gas (GHG) emissions increasing in Canada
• Mean global temperature increased about 0.6C in last 100 years (1C in Canada)
• Mean global temperatures expected to increase about 3 C this century
• Kyoto Protocol - reduce GHG by 6% below 1990 levels by 2010
• Kyoto Protocol delays doubling CO2 levels by about 15 years
Temperature Trend
Today
Source: Environment Canada
Today
Tem
per
atu
re C
han
ge
Health Concerns with Extreme Heat
• Death occurs when core body temperature rises 5 C
• Seniors and infants at increased risk due to reduced capacity for temperature regulation
• Contributory factors include high blood pressure, obesity, physical inactivity, medication use
• about 10,000 Americans died due to oppressive heat in summer 1980
• about 11,000 Europeans died from heat in summer 2003
Major Study Undertaken(Toronto Public Health, Environment Canada
and Health Canada)
• What are the combined effects of weather and air pollution?
• What can we expect in the future?
• How can we improve the heat warning system?
Key Findings - Historical Analysis
• Heat-related mortality significantly higher for seniors and those with cardiovascular illness than others
• On those days with extreme heat, average daily mortality about twice as high as for comfortable days
Key Findings - Historical Analysis
• On average (for period 1954 - 2000), of the acute deaths each year in Toronto:– 120 were heat-related– 105 cold-related– 822 were air pollution-related
• About 20% mortality associated with extreme temperature and 80% with air pollution
Distribution in Mean Annual MortalityAttributable to Extreme Temperatures and Air
Pollution
11
9
11
12
10
12
13
10
79
79
76
78
0% 20% 40% 60% 80% 100%
Windsor
Ottawa
Montreal
Toronto
% of Annual Mortality
Heat-related
Cold-related
Air pollution-related
Key Findings - Projections for Future
• Based on average of five climate change scenarios and current air emissions remaining constant, the study projects:– heat-related mortality will double by 2050 and
triple by 2080– air-pollution related mortality will increase by
20% in 2050 and 25% in 2080, largely because of increased ozone levels from global warming
• Global warming will make air pollution problems worse
Public Warning Systems
• Air Quality Index (AQI) - smog advisory issued by OMOE when AQI predicted to be 50 or greater (regional and persistent)
• Heat Health Alert system- alerts issued by Toronto Public Health (other Canadian cities exploring similar system)– Extreme Heat Alert - greater than 90%
chance of heat-related excess mortality
– Heat Alert - greater than 65% chance of heat-related excess mortality
Ontario Air Quality Index (AQI)
AQI Scale Category
0 - 15
16 - 31
32 - 49
50 - 99
100+
Very Good
Good
Moderate
Poor
Very Poor
Smog Alert
Incr
easi
ng
seve
rity
of
hea
lth
ef
fect
s At AQI = 50, OMOEcalls Air Quality Advisory
Smog Alert Days in Toronto
In 2005, Toronto experienced 48 smog alert days
15
10
35 7
9
3
20 18
1214
48
0
10
20
30
40
50
60
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Num
ber o
f Day
s
Diurnal fluctuation in hourly pollutant levels (Toronto, 1997-2000)
Toronto NO2 (1997-2000)
10
15
20
25
30
35
40
45
01 03 05 07 09 11 13 15 17 19 21 23
Hour
Co
nc
en
tra
tio
n
(pp
b)
.
Days with AQI >=50
Days with AQI <50
Toronto O3 (1997-2000)
0
10
20
30
40
50
60
70
80
01 03 05 07 09 11 13 15 17 19 21 23
Hour
Co
nc
en
tra
tio
n (
pp
b)
. Days with AQI >=50
Days with AQI <50
Diurnal fluctuation in hourly pollutant levels (Toronto, 1997-2000)
Toronto PM10 (1997-2000)
0
10
20
30
40
50
60
01 03 05 07 09 11 13 15 17 19 21 23
Hour
Co
nc
en
tra
tio
n (
ug
/m3)
Days with AQI >=50
Days with AQI <50
Toronto PM2.5 (1997-2000)
0
5
10
15
20
25
30
35
01 03 05 07 09 11 13 15 17 19 21 23
Hour
Co
nc
en
tra
tio
n (
ug
/m3)
Days with AQI >=50
Days with AQI <50
Guidance Regarding Physical Activity and Air Pollution
• Be physically active outdoors• Reduce intensity of outdoor activity at
AQI levels that trigger symptoms or when AQI exceeds 50
• To reduce exposure, plan strenuous activity such as running or jogging before morning rush hour and in low traffic areas
Proposed National Air Quality Health Index (AQHI)
Percent of days at low, moderate, high or very high health risk levels, 2001
AQHI Level Vancouver Hamilton Toronto Montreal
Low health risk
0-384 33 36 43
Moderate health risk
4-516 46 47 44
High health risk
6-101 20 16 13
Very high health risk
Over 100 0 1 0
Source: With permission from Dr. Dave Stieb, Health Canada
Heat Alert Days in Toronto
In 2005, Toronto has experienced 26 heat alert days of which 18 were in the extreme heat category
Heat Alerts 2001-05
6
14
3 2 8
3
2
3 0
18
05
1015202530
2001 2002 2003 2004 2005
Year
Nu
mb
er o
f Day
s
Extreme heat alert
Heat alert
Fluctuations in Frequency of Hot Weather Days in Toronto
(1954 to 2000)
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
1 9 5 4 1 9 5 9 1 9 6 4 1 9 6 9 1 9 7 4 1 9 7 9 1 9 8 4 1 9 8 9 1 9 9 4 1 9 9 9
Y e a r
Fre
quen
cy o
f H
ot W
eath
er
Eve
nts
3 : 0 0 p . m . T e m p e r a t u r e ≥ 3 0 ° C
H o t W e a t h e r T y p e s
Conclusions
• Air pollution continues to pose considerable health risk
• Global warming makes air pollution and its impacts worse
• Public health sector can catalyze and support reduction in emissions of air pollutants and greenhouse gases
• Heat and smog alert warning systems help individuals take personal precautions