Overview

The natural atmosphere

Outdoor pollutants and their sources

Indoor air pollution

Health effects of air pollution

Climate change

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Air Pollutants of Human Health Concern

Carbon monoxide

Sulfur dioxide

Nitrogen dioxide

Volatile organics

Ozone

Particulate matter

Sulfates, nitrates, organics, elemental carbon, lead and other metals

Carbon Monoxide - CO

Colorless, odorless gas

Primary pollutant, emitted by incomplete combustion of biomass or fossil fuels

Binds strongly with hemoglobin, displacing oxygen

Emissions reduction by higher temperature combustion and use of catalytic converters on motor vehicles

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Sulfur Dioxide – SO₂

Primary pollutant, emitted by combustion of fuels containing sulfur; also metal smelting

Irritates upper respiratory tract

Converted in atmosphere to acid sulfates

Emissions reductions by building taller smoke stacks, installing scrubbers, or by reducing sulfur content of fuel being burned

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Nitrogen Dioxide – NO₂

Formed by oxidation of NO, which is produced with high temperature combustion (NO₂ is a secondary pollutant)

Oxidant that can irritate the lungs and hinder host defense

A key precursor of ozone formation

Emissions reductions by engine redesign and use of catalytic converters

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Volatile Organic Compounds VOCs

Products of incomplete combustion, evaporation of liquid fuels, atmospheric reactions, and release from vegetation (both primary and secondary)

Wide range of compounds with varying health effects

Another key ozone precursor

Emissions reductions by high temperature combustion and control of evaporation, e.g., during refueling of cars

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Ozone – O₃

Secondary pollutant, formed via photochemical reactions in the atmosphere from NOx and VOC in the presence of sunlight

Strong oxidant that damages cells lining the respiratory system

Concentrations often highest downwind of source regions

Emissions reductions by control of NOx and VOC emissions, especially from motor vehicles

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Particulate Matter - PM

Products of combustion, atmospheric reactions, and mechanical processes

Wide range of particle sizes

Wide range of physical/chemical properties

Wide range of health impacts, including premature death

Control by filtration, electrostatic precipitation, and reduction of precursor gases

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Transportation emissions occur in close proximity to people

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Role of Diesel

Indoor Air Pollution

Combustion is principal source: cooking, smoking, heating

Dilution and dispersion are limited, especially nearest the source

Pollutants of greatest importance include: CO, NO2, PM, VOCs

Indoor concentrations often far higher than outdoors, even in urban areas

Those who spend the most time indoors near the source will be most impacted

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Health Effects of Air Pollution

Historical experience provides strong evidence for causal relationship between air pollution and premature death

Modern epidemiology studies have consistently found significant associations

Two primary epidemiologic study designs:

Time series studies of acute effects

Cohort or cross-section studies of chronic effects

Let’s look at the evidence for particle health effects…

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Air Pollution Epidemiology

Provides most directly relevant results for policy makers

Assesses effects of real mix of pollutants on human populations

Pollutants tend to co-vary, making it hard to distinguish effects

Can demonstrate associations between outcome and exposure, but not cause and effect

Must control for confounding factors

Exposure assessment is “ecologic”

Time Series Epidemiology

Addresses effects in narrow time window

Involves multiple regression analysis of long series of daily observations

Large number of studies have reported significant associations between daily deaths and/or hospital visit counts and daily average air pollution.

Time series design avoids spatial confounding; however, temporal confounding due to seasons and weather must be addressed.

Particles often appear most important, but CO, SO₂, NO₂, and/or ozone may also play roles.

For example, NMMAPS Study

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Cohort Epidemiology

Address long-term exposure-response window

Large populations in multiple cities enrolled and then followed for many years to determine mortality experience

Must control for spatial confounders, e.g., smoking, income, race, diet, occupation

Assessment of confounders at individual level is an advantage over cross-sectional, “ecologic” studies

"PM_2.5"

PM_2.5 associated with increases in daily CV mortality, CV-based hospital admissions, respiratory hospital admissions , mortality.

(Dockery, Pope, et al 1993; Schwartz 1994, Schwartz, Dockery 1996, Schwartz and Neas 2000)

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Conclusion

“Long-term exposure to combustion-related fine particle air pollution is an important environmental risk factor for cardiopulmonary and lung cancer mortality.”

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The Greenhouse Gases

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Impacts of Climate Change

General warming; greater at poles; greater in winter

Sea level rise

Changing rainfall patterns

Greater variability and intensity of weather extremes

Longer and deeper droughts

More frequent and extreme storms

Climate Change and Public Health

Changing patterns of rainfall will have profound effects on local agriculture, water supply, and well-being

Heat-related mortality and morbidity

Death and injury due to extreme storms

Changing patterns of vector-borne diseases

Air pollution

Ability to adapt will vary with income level


	The natural atmosphere
	Outdoor pollutants and their sources
	Indoor air pollution
	Health effects of air pollution
	Climate change


	Carbon monoxide
	Sulfur dioxide
	Nitrogen dioxide
	Volatile organics
	Ozone
	Particulate matter
		Sulfates, nitrates, organics, elemental carbon, lead and other metals


	Colorless, odorless gas
	Primary pollutant, emitted by incomplete combustion of biomass or fossil fuels
	Binds strongly with hemoglobin, displacing oxygen
	Emissions reduction by higher temperature combustion and use of catalytic converters on motor vehicles


	Primary pollutant, emitted by combustion of fuels containing sulfur; also metal smelting
	Irritates upper respiratory tract
	Converted in atmosphere to acid sulfates
	Emissions reductions by building taller smoke stacks, installing scrubbers, or by reducing sulfur content of fuel being burned


	Formed by oxidation of NO, which is produced with high temperature combustion (NO₂ is a secondary pollutant)
	Oxidant that can irritate the lungs and hinder host defense
	A key precursor of ozone formation
	Emissions reductions by engine redesign and use of catalytic converters


	Products of incomplete combustion, evaporation of liquid fuels, atmospheric reactions, and release from vegetation (both primary and secondary)
	Wide range of compounds with varying health effects
	Another key ozone precursor
	Emissions reductions by high temperature combustion and control of evaporation, e.g., during refueling of cars


	Secondary pollutant, formed via photochemical reactions in the atmosphere from NOx and VOC in the presence of sunlight
	Strong oxidant that damages cells lining the respiratory system
	Concentrations often highest downwind of source regions
	Emissions reductions by control of NOx and VOC emissions, especially from motor vehicles


	Products of combustion, atmospheric reactions, and mechanical processes
	Wide range of particle sizes
	Wide range of physical/chemical properties
	Wide range of health impacts, including premature death
	Control by filtration, electrostatic precipitation, and reduction of precursor gases


	Combustion is principal source: cooking, smoking, heating
	Dilution and dispersion are limited, especially nearest the source
	Pollutants of greatest importance include: CO, NO2, PM, VOCs
	Indoor concentrations often far higher than outdoors, even in urban areas
	Those who spend the most time indoors near the source will be most impacted


	Historical experience provides strong evidence for causal relationship between air pollution and premature death
	Modern epidemiology studies have consistently found significant associations
	Two primary epidemiologic study designs:
		Time series studies of acute effects
		Cohort or cross-section studies of chronic effects
	Let’s look at the evidence for particle health effects…


	Provides most directly relevant results for policy makers
	Assesses effects of real mix of pollutants on human populations
	Pollutants tend to co-vary, making it hard to distinguish effects
	Can demonstrate associations between outcome and exposure, but not cause and effect
	Must control for confounding factors
	Exposure assessment is “ecologic”


	Addresses effects in narrow time window
	Involves multiple regression analysis of long series of daily observations
	Large number of studies have reported significant associations between daily deaths and/or hospital visit counts and daily average air pollution.
	Time series design avoids spatial confounding; however, temporal confounding due to seasons and weather must be addressed.
	Particles often appear most important, but CO, SO₂, NO₂, and/or ozone may also play roles.
	For example, NMMAPS Study


	Address long-term exposure-response window
	Large populations in multiple cities enrolled and then followed for many years to determine mortality experience
	Must control for spatial confounders, e.g., smoking, income, race, diet, occupation
	Assessment of confounders at individual level is an advantage over cross-sectional, “ecologic” studies


	PM_2.5 associated with increases in daily CV mortality, CV-based hospital admissions, respiratory hospital admissions , mortality.

	(Dockery, Pope, et al 1993; Schwartz 1994, Schwartz, Dockery 1996, Schwartz and Neas 2000)


	“Long-term exposure to combustion-related fine particle air pollution is an important environmental risk factor for cardiopulmonary and lung cancer mortality.”


	General warming; greater at poles; greater in winter
	Sea level rise
	Changing rainfall patterns
	Greater variability and intensity of weather extremes
		Longer and deeper droughts
		More frequent and extreme storms


	Changing patterns of rainfall will have profound effects on local agriculture, water supply, and well-being
	Heat-related mortality and morbidity
	Death and injury due to extreme storms
	Changing patterns of vector-borne diseases
	Air pollution
	Ability to adapt will vary with income level