Outdoor and Indoor Air Pollution

Patrick L. Kinney, Sc.D.

Associate Professor

Columbia University

[email protected]

Overview

The natural atmosphere

Outdoor pollutants and their sources

Indoor air pollution

Health effects of air pollution

Measurement of particle pollution

Climate change

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Troposphere

Lowest 10 km of atmosphere

Contains 75% of the atmospheric mass

The layer in which most weather phenomena occur, e.g., frontal passage, storms, winds

The layer in which most air pollution problems occur

Energy balance is key factor

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Air set in motion by:

Absorption of energy at surface followed by transfer of heat to lowest layer of air

Heated parcels become buoyant relative to nearby cooler parcels, thereby rising

Rising of air parcel leaves lower pressure at surface

Dense, cool air moves towards the area of low pressure

Pressure gradient force drives winds

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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

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

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

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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Figure 3.2 Trends in estimated U.S. Lead Emissions

Figure 3.3 Trends in U.S. Ambient Lead Concentrations

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

Cox proportional hazards modeling to determine associations with pollution exposure

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

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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.”

Human Health Effects of Airborne Particulate Matter

Daily time-series studies have demonstrated small but consistent associations of PM with mortality and hospital admissions, reflecting acute effects.

Acute effects on lung function, asthma exacerbations, and other outcomes

Multi-city prospective cohort studies have shown increased mortality risk for cities with higher long-term PM concentrations, reflecting chronic effects.

Implications

Acute effects are well documented but of uncertain significance

Chronic effects imply very large impacts on public health.

A new US national ambient air quality standard for PM_2.5 was established in 1997, largely based on the cohort epidemiology evidence

Mechanistic explanation for chronic effects remains unclear

Weaknesses in exposure assessment limits interpretation

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It is also unclear…

Whether a threshold exists

Who is at risk due to

Higher exposures

Greater susceptibility

What particle components are most toxic

Which sources should be controlled

Measurement of Airborne Particulate Matter

Getting the size right

A look at some field studies

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Analysis of Particle Samples

Mass determined by weighing Teflon filter before and after sampling under controlled conditions

Elemental carbon estimated by light absorption

Analysis of trace elements by ICP-mass spectrometry

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Winter NYC Individual Data:
Indoor and Outdoor vs. Personal Absorbance

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Elevated personal samples are consistent with steel dust in subway air!

Preliminary Conclusions

We see strong urban influences on air toxic exposures for some particle components.

Personal exposures are closely associated with outdoor concentrations of black carbon, an indicator of diesel exhaust particles.

Diesel particle exposures are associated with lung cancer and have been suggested to play a role in asthma.

New studies underway to examine the diesel/asthma link.

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The Greenhouse Gases

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US greenhouse gas emission trends

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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

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New York Climate and Health Project

How might health in the NY metropolitan region be affected by climate and land use change?

Mailman School of Public Health:

Patrick Kinney (PI) – Public health impact analysis

Goddard Institute for Space Studies:

Cynthia Rosenzweig – Global and regional climate modeling

LDEO: Chris Small – Remote sensing

Hunter College: Bill Solecki – Regional land-use/land-cover modeling

SUNY Albany: Christian Hogrefe – Regional air quality modeling

Duke University: Roni Avissar – Regional climate modeling

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	Patrick L. Kinney, Sc.D.
	Associate Professor
	Columbia University
	[email protected]


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


	Lowest 10 km of atmosphere
	Contains 75% of the atmospheric mass
	The layer in which most weather phenomena occur, e.g., frontal passage, storms, winds
	The layer in which most air pollution problems occur
	Energy balance is key factor


	Absorption of energy at surface followed by transfer of heat to lowest layer of air
	Heated parcels become buoyant relative to nearby cooler parcels, thereby rising
	Rising of air parcel leaves lower pressure at surface
	Dense, cool air moves towards the area of low pressure
	Pressure gradient force drives winds


	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
	Cox proportional hazards modeling to determine associations with pollution exposure
	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


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


	Daily time-series studies have demonstrated small but consistent associations of PM with mortality and hospital admissions, reflecting acute effects.
	Acute effects on lung function, asthma exacerbations, and other outcomes
	Multi-city prospective cohort studies have shown increased mortality risk for cities with higher long-term PM concentrations, reflecting chronic effects.


	Acute effects are well documented but of uncertain significance
	Chronic effects imply very large impacts on public health.
	A new US national ambient air quality standard for PM_2.5 was established in 1997, largely based on the cohort epidemiology evidence
	Mechanistic explanation for chronic effects remains unclear
	Weaknesses in exposure assessment limits interpretation


	Whether a threshold exists
	Who is at risk due to
		Higher exposures
		Greater susceptibility
	What particle components are most toxic
	Which sources should be controlled


	Mass determined by weighing Teflon filter before and after sampling under controlled conditions
	Elemental carbon estimated by light absorption
	Analysis of trace elements by ICP-mass spectrometry


	We see strong urban influences on air toxic exposures for some particle components.
	Personal exposures are closely associated with outdoor concentrations of black carbon, an indicator of diesel exhaust particles.
	Diesel particle exposures are associated with lung cancer and have been suggested to play a role in asthma.
	New studies underway to examine the diesel/asthma link.


	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


	How might health in the NY metropolitan region be affected by climate and land use change?
	Mailman School of Public Health:
	Patrick Kinney (PI) – Public health impact analysis

	Goddard Institute for Space Studies:
	Cynthia Rosenzweig – Global and regional climate modeling

	LDEO: Chris Small – Remote sensing

	Hunter College: Bill Solecki – Regional land-use/land-cover modeling

	SUNY Albany: Christian Hogrefe – Regional air quality modeling

	Duke University: Roni Avissar – Regional climate modeling