Home sweet home . . .
Or is it????
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%
Pollution terminology
• Pollutant
• Source
• Effect
Article: EPA Proposes New
Ozone Standard
• EPA = Environmental Protection Agency
Pollution units
Parts per thousand (ppt)
Parts per million (ppm)
Parts per billion (ppb)
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 a source
•
Mobile sources
Mobile sources
Stationary Sources
• Power plants
Refineries
Secondary pollutants form in
atmosphere as gases react
• Smog, ground level ozone and
acid rain
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
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
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
We're #?
• . . . .for the number of days exceeding
allowable ground level ozone levels.
• American Lung Association State of the
Air
We're #?
• . . . .for the number of days exceeding
allowable ground level ozone levels.
• American Lung Association State of the
Air
Measuring pollutants
•
•
•
•
parts per thousand = ppt
parts per million = ppm
Parts per billion = ppb
Parts per trillion = ppt (must know from
context)
Clean Air Act
• Passed by Congress in 1970, updated in
1990, ‘93, 97, 2008.
• Required EPA (Environmental Protection
Agency) 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
Houston’s special issues
• 1/3 of all US petrochemicals pass through
our refineries
• Refineries separate crude oil into many
different products from asphalt tar to
gasoline to butane
Refineries create carcinogenic
air pollutants
Benzene,
toluene,
ethylbenzene,
xylenes
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!
• What is the difference between a primary
and a secondary air pollutant?
• Give an example of a mobile source.
• Give an example of a stationary source.
• Which layer of the atmosphere are you in
RIGHT NOW?!!!!
• What is the normal chemical composition
of our atmosphere?