Air Quality 101 Rice Air Curriculum Teacher Training.

Air Quality 101

Rice Air CurriculumTeacher Training

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Leading Atmospheric Constituents

• Nitrogen (N2) 78%

• Oxygen (O2) 21%

• Argon (Ar) 1%

• Water Vapor (H2O) 0-3%

• Carbon dioxide (CO2) 0.039%

Most air pollutants are in very small quantities (parts per million or billion) but affect our health

and climate.

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Categories of Atmospheric Compounds• Air pollutants: Substances that directly harm

health of humans, wildlife, or vegetation– Air toxics: Carcinogens, mutagens, neurotoxins– Respiratory irritants– Substances that cause cardio-vascular impacts– Substances that damage crops, forests, ecosystems

• Particulate matter: Solid or liquid microscopic particles suspended in air

• Ozone depleters: Substances that destroy stratospheric ozone

• Climate-influencing compounds: Greenhouse gases and particles that impact radiative budget

Particulate Matter

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Particulate Matter• Aerosol: Liquid or solid particles suspended in air• Wide range of chemical composition• Sizes range from <1nm to >10 μm

– Large particles settle out quickly– Fine particles (<2.5 μm (PM2.5)) most damaging to visibility

& health (respiratory, cardio-vascular, mortality)

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Impacts of PM• Health effects

– Fine particles go deep in lungs, to bloodstream– Respiratory and cardiovascular disease– Mortality

• Visibility/Haze• Climate• Regulatory concern

– Houston barely attains current standard– EPA tightened 24-hr but not annual standard

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Ozone (O3)

Stratospheric & Tropospheric Ozone:“Good up high, Bad nearby”

• In stratosphere, ozone forms naturally when Sun’s intense UV rays split oxygen:– O2 + hv O + O

– O + O2 O3

– This “good ozone” blocks UV rays– Stratospheric ozone can be destroyed by CFCs

• In troposphere, intense UV rays already blocked. Ozone instead forms as a pollutant:– Nitrogen oxides + Hydrocarbons + Sunlight O3

– “Bad ozone”: air pollutant and greenhouse gas

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Stratospheric Ozone Hole

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Montreal Protocol drastically curtailed ozone depleting emissions

WMO/UNEP Scientific Assessment of Ozone Depletion, 2010

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Impacts of Montreal Protocol:Halocarbon Concentrations

NOAA

45 yrlifetime

100 yrlifetime

5 yrlifetime

35 yrlifetime

Ozone projected to recover as halocarbon levels decline

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NO

NO2

HO2

OH

RO2

VOC

O3

Ground-level Ozone “Smog”

VOC NOx O3

HydrocarbonsNitrogenOxides

Sunlight & Heat

Tropospheric NOx Cycle

N2O NO NO2

O3

hνHNO3

O(1D) O ClONO2

BrONO2

ClO, BrO

Red: Ox destructionGreen: Ox productionBlack: No change in Ox

Blue: Reservoir Species*: Dominant pathway during daytime

hv

OH

NO3

O3

hν

N2O5

HO2 and CH3O2, other RO2

CO, CH4, VOCs

Oxidation by

OH, etc.

Directemissions

hν

*

*

deposition

Sources of Ozone-forming Emissions

• Nitrogen Oxides– Vehicles– Power plants– Other industry and equipment

• Hydrocarbons– Natural vegetation– Vehicles– Refineries / Chemical plants– Other sources

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Ozone Impacts

• Health effects– Asthma and other respiratory illnesses– Recently linked to mortality

• Regulatory concern– Houston, Dallas, many other cities fail to

attain limits

• Atmospheric oxidant– Oxidizes certain VOCs– Contributes to formation of OH oxidant

• Greenhouse gas

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Emissions Trends

Strong declines in ozone, but many cities still exceed 75 ppb

18http://www.tceq.state.tx.us/assets/public/implementation/air/sip/hgb/hgb_sip_2009/09017SIP_Ch5_ado.pdf

Houston US Cities

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Ozone Non-attainment: 75 ppb standard

Map from US EPA

Climate Change Overview

• Is Earth warming?

• Natural or anthropogenic causes?– Overview Earth’s radiative balance &

greenhouse effect

• Impacts

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Evidence of recent climate change

IPCC, 2007

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National Geographic

Global US

Additional evidence of warming

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IPCC, Physical Basis Technical Summary, 2007

Past decade was warmest recorded

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Hansen et al 2010

This summer’s weather

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http://www.columbia.edu/~mhs119/Temperature/

Anomaly (°C) relative to 1951-1980 mean

In the news: Arctic sea ice reaches all time minimum extent, August 26, 2012

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NASA: http://climate.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=767

Yellow line shows average minimum, 1979-2010

Climate Fundamentals: Earth’s Radiative Balance and Greenhouse Effect

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(Trenberth et al., BAMS, March 2009)

Yellow: Solar UV

and Visible Radiation

Beige: Infrared

Radiation

Radiation proportional to TK

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Greenhouse gases absorb and re-radiate infrared at atmosphere’s cooler temperature

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Earth’s Carbon Cycle

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Rising Greenhouse Gas Levels

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IPCC, 2007

CO2

CH4

N2O

Total Radiative Forcing

Causes of Radiative Forcing, 1750-2005

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IPCC, 2007

Greenhouse gas radiative forcing (W/m2) well understood

Key Scientific Uncertainty: How much warming per radiative forcing (°C/W-m2)

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IPCC, 2007

Both anthropogenic and natural forcings are needed to model temperature record

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IPCC, 2007

Projected Impacts of Further Warming

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IPCC, Impacts SPM, 2007