Take a deep breath!
Please read the board.
Please find your notes from
yesterday
Breathing!
Some basics
What is in our atmosphere?
Normal chemical
composition of our
atmosphere:
(N2) 78%
(O2) 21%
Trace gases (water,
argon, carbon
dioxide, other
pollutants) 1%
Measuring pollutants
• parts per thousand = ppt
• parts per million = ppm
• Parts per billion = ppb
Clean Air Act
• Passed by Congress in 1970, updated in
1990.
• Required EPA to identify criteria pollutants
and to establish minimum standards: EPA
came up with NAAQ’s
National Ambient Air Quality
Standards
• Six criterion pollutants: NOx, SOx, O3, Pb,
CO, particulates
• Established minimum standards: 1hr and
8 hr
• EPA is working to have greenhouse gases
added by Congress to the NAAQs
Ground level ozone in Htown
Smog and ozone form together
1.
2.
3.
4.
N2 + O2  2NO
2NO + O2  2NO2
NO2 + UV radiation  NO + O
O + O2  O3
Primary pollutants
•
Come directly from source
• Step one: N2 + O2  2NO
Secondary pollutants form in
atmosphere as gases react
• Step two: 2NO + O2  2NO2
• NO2 is smog – a yellow brown
gas
• Causes lung and eye irritation,
makes asthma, bronchitis and
emphysema worse
Ozone formation
Step 3: NO2 + UV radiation  NO + O
Step 4:O + O2  O3
Ozone slows photosynthesis,
eye and lung irritant, makes
asthma, emphysema,
bronchitis worse
Fill in your first flip chart
page!
Brown pencils please!
VOCs – a second route for O3
formation
• Volatile Organic Compounds:
– Methane (CH4)
– Propane
– Chlorofluorocarbons (CFC)
– VOCs can break O2 into free oxygen atoms
(free radicals)
– VOC + O2  VOC + 2O
– O + O2 O3
Check out ozone formation
• Texas Commission on Environmental
Quality
– EPA: National/Federal Regulatory agency
– TCEQ: state regulatory agency
• ozone animation
Houston Clean Air Network Map
AQI: set at 100 for each criterion
pollutant level.
Ozone 100 AQI = 85ppb
Smog and ozone form together
1.
2.
3.
4.
N2 + O2  2NO
2NO + O2  2NO2
NO2 + UV radiation  NO + O
O + O2  O 3
Ozone season: March- November
Ozone daily formation: noon-early
evening
We're #?
• . . . .for the number of days exceeding
allowable ground level ozone levels.
• American Lung Association State of the
Air
Observations/Inferences
Year
High ozone days 1 hr
average/ highest
recorded
High ozone days
8 hr average
2012
8 days/143 ppb
35 days/121ppb
2010
7 days/149 ppb
44 days/97ppb
2009
6 days/157ppb
28 days/110ppb
2008
6days/143ppb
31days/106 ppb
2007
9 days / 166 ppb
46 days / 112 ppb
2006
20 days/165ppb
62 days/126 ppb
So what is being done about
this? - City monitoring
45 mobile monitoring stations
State monitoring
• Flexible permitting – each facility has total
cap emissions limit, but flexibility in how
they meet that limit.
• TCEQ issues permits for emitting certain
amount of pollutants
• Facilities do “self reporting”
Check your understanding!
• Why are we more likely to hit an orange
AQI at 3pm in August than at 8am in
December?
• Why is it important that Houston improve
its air quality?