Air Pollution and Health Recent Findings and Next Steps
Transcript of Air Pollution and Health Recent Findings and Next Steps
Air Pollution and Health
Recent Findings and Next Steps
Antonella Zanobetti
Principal Research Scientist
Department of Environmental Health
Harvard T.H. Chan School of Public Health
Background• Adverse effects of air pollution on health: 3 disasters in
which high levels of air pollution associated with high
number of deaths
Mosa Valley, Belgium 1930 (Firket, 1936)
Donora, PA USA 1948 (Shrenk, 1948)
London, UK 1952 (Ministry of Health, 1987)
China: heavy haze in Beijing, January
2013.
• The association between exposure to particulate matter (PM) and
mortality or morbidity is well established
• Particulate air pollution has been associated with increases in daily
deaths and hospital admissions in many studies across the world
• Air pollution remains a serious, overwhelming problem
Background
Recent Air Pollution Facts
10 Top Risk Factors Ranked by Attributable Burden
of Disease in 2010 (disability adjusted life years)
#3: Household air pollution from solid fuels
#9: Ambient particulate matter pollution
Lim et al., A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters
in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. The Lancet (2012)
Global Public Health Impact
• In 2010, globally:
• Ambient particulate matter pollution accounted for:
– 3.2 million excess deaths
– 3.1% of disability adjusted life years (DALYs)
• Household air pollution from solid fuels accounted for:
– 3.5 million excess deaths
– 4.3% of disability adjusted life years (DALYs)
• Household air pollution is an important contributor to ambient particulate matter pollution
– Account for 16% of the worldwide burden from ambient particulate matter pollution in 2010
Lim et al. Lancet. 2012
Recent Air Pollution Facts
Ratio of estimated 2005:1990 PM2.5 concentrations
Between
1998–2012,
global ambient
PM2.5
concentrations
increased by
2.1% / year
Brauer et al., Environ. Sci. Technol. (2012); van Donkelaar et al., EHP (2015)
Reducing particle pollution
• National Research Council (NRC) stated most important research priorities:
• to set standards for criteria pollutants
• to understand the relationship between particulate matter and public health
• Under the Clean Air Act, US Environmental Protection
Agency (EPA) set National Ambient Air Quality Standard
(NAAQS) for criteria pollutants
– ozone, lead, sulfur oxides, nitrogen oxides, and particulate matter
– periodically revised
What is Particulate Matter?
• "Particulate matter," also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets found in the air.
Common Sources:
• Primary particles are emitted directly from a source: – dust, fuel combustion, motor vehicles, industrial, fires
• Secondary particles formed in complicated reactions in the atmosphere of chemicals emitted from power plants, industries and automobiles.
These particles make up most of the fine particle pollution in the US.
How Big is Particle Pollution?
How small is 2.5 micrometers?
The average human hair is about 70-100 micrometers in diameter – making it 30
times larger than the largest fine particle.
Grouped into size categories:
Inhalable particles (PM10) <= 10 mm in diameter.
Fine particles (PM2.5) are 2.5 mm in diameter and smaller.
Inhalable coarse particles (PM10-2.5) >=2.5 mm and <= 10 mm in diameter
Robert D. Brook et al. Circulation. 2004;109:2655-2671
How Air Quality Affects Health1
Enter body through
the nose and throat
2|3
Larger particles (PM10)
are eliminated
4
PM2.5 penetrate into
the lungs/alveoli
http://www.bcairquality.ca/health/air-quality-and-health.html
Identifying and quantifying the influence of
environmental factors on human disease in
communities to provide scientific evidence for
environmental and health policies.
1. Quantify relationship between air pollution and health
2. Develop mathematical and statistical tools to examine this
relationship
3. Identify subpopulations most susceptible to adverse health
effects from air pollution exposure
4. Study the physiologic mechanisms by which ambient air
pollution mediates adverse health effects
5. Development of models to improve monitoring and exposure
methods.
Existing literature
• Many studies around the world found significant
associations between particulate matter and health
outcomes– all-cause and cause-specific mortality
– cardiovascular & respiratory outcomes
– lung cancer etc
• Short-term exposure (few days)
Acute health effects
• Long-term exposure (few years)
Chronic health effects
Examples studies of
short term PM2.5 effects1. Fine particles (PM2.5) are more harmful to health than larger
particles (PM10)
– Coarse particles (=PM10-PM2.5) are not regulated by U.S. EPA
We test the hypothesis that PM2.5 and PM coarse are
associated with mortality
2. Possible mechanisms of mortality/PM2.5 associations
include: oxidative stress systemic inflammation, and
cerebrovascular dysfunction
– These are related to neurovascular dysfunction and
neurodegeneration
Examine if exposure to PM2.5 increases the risk of
hospitalization for diabetes or neurological disorders
The Effect of Fine and Coarse Particulate Air
Pollution On Mortality: A National Analysis
Map of the 112 US cities included in the study.
Symbol size: the population
Color: PM2.5 concentrations
We conducted a multi-city time series study of the acute effect
of PM2.5 and of PM coarse on the increased risk of death
Zanobetti A & Schwartz J. Environ Health Perspect, 2009;117(6):898-903
Health data
Counts of mortality from NCHS
for years 1999-2005 all cause mortality
cardiovascular disease
myocardial infarction
stroke
respiratory disease
Environmental Data
PM10 PM2.5 ambient monitors from US EPA’s Air Quality System
Technology Transfer Network (EPA
AQS)
-1
0
1
2
3
4
5
6
Percent increase (95% CI) for 10 mg/m3 increase in PM2.5.
Combined results across 112 cities of the mortality PM2.5
association, for the two days mean, sum of 4 days
distributed lag and for the two days mean by season.
PM2.5 PM coarse
% 95% CI % 95% CI
All cause
mortality 0.77 0.43 1.12 0.47 0.21 0.73
CVD 0.61 0.05 1.17 0.29 -0.04 0.61
MI 0.75 -0.12 1.63 0.04 -0.72 0.81
STROKE 0.82 -0.21 1.86 0.71 0.02 1.41
Respiratory 1.63 0.69 2.59 1.14 0.43 1.85
Percent increase in mortality for 10 µg/m3 increase
in PM coarse and PM2.5 for the two days mean,
across the 47 cities: two- pollutant model. Increased risk of mortality for all and specific causes
associated with PM2.5 and with PM coarse
The risks are higher than what previously observed for PM10.
Health Data Medicare data for citizens >65 years
Hospitalizations:
Dementia (N=717,000)
Alzheimer's disease(N=1,335,000)
Parkinson’s disease (N=714,000)
Multiple sclerosis(N=66,000)
Diabetes(N=8,245,000)
Deaths (N=6,983,000)
Environmental DataPM2.5 from US EPA AQS
2 days average
Map of the 121 US cities
A national case-crossover analysis of the short-term effect
of PM2.5 on hospitalizations and mortality in subjects with
diabetes and neurological disorders.
Zanobetti A, et al. Environ Health 2014;13(1):38.
1. The association between short-term exposure to PM2.5 and all-cause mortality is
modified by having a previous hospitalization of diabetes or neurological disorders.
2. Exposure to PM2.5 increases the risk of
hospitalization for diabetes or neurological
disorders
Percent Increase in mortality and admissions
for 10 mg/m3 Increase in the 2 Days Average PM2.5% 95% CI
1) Mortality
All deaths 0.64 0.42 0.85
Deaths without medical conditions 0.60 0.36 0.84
Mortality by Previous Cause of Hospitalization
Alzheimer's disease 1.04 0.36 1.72
Dementia 0.94 0.01 1.89
Parkinson's disease 1.15 0.09 2.23
Multiple Sclerosis 4.01 -0.03 8.21
Diabetes 0.76 0.39 1.12
2) Cause Specific Hospitalizations
Alzheimer's disease 0.20 -1.26 1.69
Dementia 0.92 -0.44 2.30
Parkinson's disease 3.23 1.08 5.43
Multiple Sclerosis 0.52 -5.36 6.77
Diabetes 1.14 0.56 1.73
Examples studies of
long term PM2.5 effects
1. Increased interest in the effects of air pollution on the
central nervous system and neurodegeneration
Examined the potential effect of long-term PM2.5 exposure on first
admission for dementia, Alzheimer’s or Parkinson’s diseases
2. To identify spatial locations and population sub-groups that
are more vulnerable to the effects of the exposure
We assessed whether community-level variables, including
socioeconomic status (SES) indicators, increased urbanicity and
temperature modify the association between long term exposure to
PM2.5 and mortality.
Long-term PM2.5 Exposure and Neurological
Hospital Admissions in the Northeastern US
Health Data Medicare enrollees (1999-2010)
9.8 M subjects
> 266K Alzheimer’s (AD)
> 119 K Parkinson’s (PD)
Mean age: 76.6 yr (SD: 7.6),
57.3% female, 80.4% white
Environmental DataPM2.5 from US EPA AQS Annual averages
50 cities across 12 Northeastern States
Kioumourtzoglou MA et al. EHP 2015
Assess the potential impact of long-term PM2.5 exposure on event time,
defined as time to the first admission for dementia, Alzheimer’s or
Parkinson’s diseases
Findings
• City-specific Cox proportional hazard models– No confounding across cities, by long-term trends or individual
characteristics
Per 1 μg/m3 annual PM2.5:
• Alzheimer’s Disease: HR = 1.15 (1.11, 1.19)
• Parkinson’s Disease: HR = 1.08 (1.04, 1.12)
• One of the first study to examine the relationship between long term exposure to PM2.5 and time to the first hospitalization for the most common neurodegenerative diseases.
• Our findings provide the basis for more studies, as the implications to public health can be crucial.
Long-term exposure to PM2.5 and mortality in 207
US cities: Modification by temperature, population
characteristics and green space
• City-level characteristics:
• Census:– median household income – % in poverty – % of white, black and Asian – % of residents with and without
high-school degrees and with a college degree
Health Data >35M Medicare enrollees (1999-2010)
Observed >11M deaths
Environmental DataPM2.5 from US EPA AQS
Annual averages
• Smart Growth America: Urbanicity
• Behavioral Risk Factor
Surveillance System:• city-specific smoking (2000–2010)
• obesity rates (2004–2010)
• Normalized Difference Vegetation
Index (NDVI).• Greenness Kioumourtzoglou et al., Epidemiology 2015
Effect modification on the PM2.5–mortality association,
HRs per 10 μg/m3 at the 25th and 75th % of each variable
Living in cities
with low SES
is associated
with higher
effect
estimates.
HR = 1.19 (1.11, 1.28) per 10 μg/m3 annual PM2.5
Largest
national study
for long-term
PM2.5 and
mortality
Issues in existing studies
• Long-term and short-term exposure to fine particulate
matter has been consistently associated with adverse
health
• Previous studies have generally focused on:
– Either long-term or short-term exposures
– Exposure across the entire range of PM2.5 concentrations
– Use monitored data
Issues in existing studies
• Rural areas are not generally represented
• Spatial variability in PM2.5 concentrations within cities not
taken into account, which can introduce exposure
measurement error
• No simultaneous estimate of long-term and short term
effects
• Relevant to future assessments of current U.S. EPA
standards
– Health effects when air quality concentrations are at or below
the existing NAAQS levels
Moving forward
1. Improve exposure assessment
2. Estimate health effects when air quality
concentrations are at or below the existing or
alternative NAAQS levels
– U.S. EPA review NAAQS every 5 years
– Idea is that if significant effects are seen at lower level of
the existing NAAQS, there is support for the NAAQS not
being adequate to protect public health
Improving Exposure assessment• Monitoring stations:
• Usually average across available monitoring stations in a county• Represent the average exposure concentration for all population• Temporal variation
• Land Use Regression models• Uses spatial patterns of land use, such as population density, distance to
roads, etc. to predict PM measurements at monitoring stations and apply the predictions elsewhere
• To assess long–term exposure
• Provide good estimates of spatially resolved long-term exposures, but are poor at capturing short term exposures
• Spatial variation
• Spatio-temporally resolved predictions
Spatio-temporally resolved predictions
• Include both spatial and temporal
variables
ground PM2.5 measurements
land use regression variables
meteorological variables
Satellite-based remote sensing data on
aerosol optical depth (AOD).
Kloog I, et al. Atmospheric Environment, 2011, 45, 35, p. 6267-6275
• Novel spatio-temporally resolved predictions PM2.5
concentrations at the grid level (1km x 1km)
• Daily predictions (short and long term exposure)
Low-Concentration PM2.5 and Mortality:
Estimating Acute and Chronic
Effects in a Population-Based Study
• The present study aimed to:
1. Simultaneously estimate acute and chronic health
effects of PM2.5 in a population-based cohort (≥ 65
years of age) in New England region
2. PM2.5 satellite based predictions
3. Estimate the effects of low-concentration PM2.5 on
mortality
Shi L, et al. Environ Health Perspect 124:46–52, 2016
Data
Health Data Medicare enrollees (2003-2008)
• Daily count of death for each ZIP code
Environmental Data
PM2.5: Spatio-temporally resolved predictions
Short term exposure (2-day average, lag01)
Long term exposure (365-day moving avera
ge)
Restricted to annual concentrations below
10 µg/m3 or daily concentrations below
30 µg/m3
Mean PM2.5 concentrations in 2004 at a
high resolution (1 km x 1 km) across New
England predicted by the AOD models
Percent increase in mortality for a 10 µg/m3
increase for PM2.5
Shi et al., EHP,2015
PM2.5 exposure type Model Percent increase p-value
Short-term PM2.5 exposure Low daily exposure a 2.14 (1.34,2.95) <.001
Full cohort 2.14 (1.38,2.89) <.001
Long-term PM2.5 exposure Low chronic exposure b 9.28 (0.76,18.52) 0.032
Full cohort 7.52 (1.95,13.40) 0.007
Using a mutually adjusted model, we found that short- and long-term
exposure to PM2.5 were associated with all-cause mortality, even for
exposure levels not exceeding the newly revised U.S. EPA standards
a Restricted only to person time with daily PM2.5 less than 30 µg/m3.b Restricted only to person time with chronic PM2.5 less than 10 µg/m3.
Below daily PM2.5 NAAQS (35 µg/m3) Below annual PM2.5 NAAQS (12 µg/m3)
Dose-response relationship for low-
concentration PM2.5 and mortality
• Adverse health effects occur at low levels of fine particles
• Improving air quality below the current PM2.5 NAAQS can
still yield health benefits
Conclusion• Based on the literature there is a causal effect of short-term
exposures to PM2.5 and mortality
• Strong evidence for other outcomes and for chronic exposure
Moving Forward• Changes in the standards require additional studies to
elucidate whether health effects occur at levels below the current annual and daily U.S. EPA NAAQS of 12 and 35 μg/m3
• More studies estimating acute and chronic effects of cardiovascular morbidity outcomes associated with short and long-term exposure to PM2.5, in both rural and urban areas, and at low concentrations.
Acknowledgments
Joel Schwartz, Diane Gold, Petros Koutrakis
Francesca Dominici, Brent Coull
Marianthi-Anna Kioumourtzoglou, Itai Kloog
Marc G. Weisskopf, Liuhua Shi
Clean Air Research Center
(CLARC) RD 83479801
834900
Harvard-NIEHS Center for Environmental Health P30ES000002
R21 ES024012, R01 ES024332
THANK YOU!