Air Quality 101 Rice Air Curriculum Teacher Training

2 Leading Atmospheric Constituents Nitrogen (N 2 )78% Oxygen (O 2 )21% Argon (Ar)1% Water Vapor (H 2 O)0-3% Carbon dioxide (CO 2 )0.039% Most air pollutants are in very small quantities (parts per million or billion) but affect our health and climate.

3 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 4

5 Aerosol: Liquid or solid particles suspended in air Wide range of chemical composition Sizes range from 10 μm –Large particles settle out quickly –Fine particles (<2.5 μm (PM 2.5 )) most damaging to visibility & health (respiratory, cardio-vascular, mortality)

6 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

7 Ozone (O 3 )

Stratospheric & Tropospheric Ozone: “Good up high, Bad nearby” In stratosphere, ozone forms naturally when Sun’s intense UV rays split oxygen: –O 2 + hv  O + O –O + O 2  O 3 –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  O 3 –“Bad ozone”: air pollutant and greenhouse gas

9 Stratospheric Ozone Hole

10 Montreal Protocol drastically curtailed ozone depleting emissions WMO/UNEP Scientific Assessment of Ozone Depletion, 2010

11 Impacts of Montreal Protocol: Halocarbon Concentrations NOAA 45 yr lifetime 100 yr lifetime 5 yr lifetime 35 yr lifetime

Ozone projected to recover as halocarbon levels decline 12

13 NO NO 2 HO 2 OH RO 2 VOC O3O3 Ground-level Ozone “Smog” VOC NO x O3O3 Hydrocarbons Nitrogen Oxides Sunlight & Heat

Tropospheric NO x Cycle N2ON2O NONO 2 O3O3 hνhν HNO 3 O( 1 D)OClONO 2 BrONO 2 ClO, BrO Red: O x destruction Green: O x production Black: No change in O x Blue: Reservoir Species *: Dominant pathway during daytime hv OH NO 3 O3O3 hνhν N2O5N2O5 HO 2 and CH 3 O 2, other RO 2 CO, CH 4, VOCs Oxidation by OH, etc. Direct emissions hνhν * * deposition

Sources of Ozone-forming Emissions Nitrogen Oxides –Vehicles –Power plants –Other industry and equipment Hydrocarbons –Natural vegetation –Vehicles –Refineries / Chemical plants –Other sources 15

16 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

17 Emissions Trends

Strong declines in ozone, but many cities still exceed 75 ppb 18 sip/hgb/hgb_sip_2009/09017SIP_Ch5_ado.pdf HoustonUS Cities

19 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 20

21 Evidence of recent climate change IPCC, 2007

22 National Geographic Global US

Additional evidence of warming 23 IPCC, Physical Basis Technical Summary, 2007

Past decade was warmest recorded 24 Hansen et al 2010

This summer’s weather 25 Anomaly (°C) relative to mean

In the news: Arctic sea ice reaches all time minimum extent, August 26, NASA: Yellow line shows average minimum,

Climate Fundamentals: Earth’s Radiative Balance and Greenhouse Effect 27 (Trenberth et al., BAMS, March 2009) Yellow: Solar UV and Visible Radiation Beige: Infrared Radiation Radiation proportional to T K 4

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Greenhouse gases absorb and re-radiate infrared at atmosphere’s cooler temperature 29

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Earth’s Carbon Cycle 31 (IPCC 2007, Physical Basis Chapter 7)

Rising Greenhouse Gas Levels 32 IPCC, 2007 CO 2 CH 4 N2ON2O Total Radiative Forcing

Causes of Radiative Forcing, IPCC, 2007 Greenhouse gas radiative forcing (W/m 2 ) well understood

Key Scientific Uncertainty: How much warming per radiative forcing (°C/W-m 2 ) 34

IPCC, 2007 Both anthropogenic and natural forcings are needed to model temperature record

36 IPCC, 2007

Projected Impacts of Further Warming 37 IPCC, Impacts SPM, 2007