Unit 7 - Atomspheric Pressure

## 7.1 Introduction to Air Pollution

* air pollution: anything in the atmosphere that is harmful to organisms
* primary pollutants: emitted directly into the atmosphere
* can be natural or anthropogenic (produced by humans)
* ex. pollen, plant VOCs, volcanic ash, fossil fuel combustion
* secondary pollutants: forms after entering the atmosphere
* as a result of interactions with other atmospheric gases or sunlight rays
* ex. ozone, acid rain
* sources of pollution can be natural, mobile, or stationary
* NAAQS of Clear Air Act: established standards to identify air pollutants
* includes SO2, PM, Pb, O3, NO2, CO
* health effects of lead: anemia, lower IQ, nerve damage, behavioral issues, hypertension, cardiovascular disease, reading/learning disabilities
* combustion of fossil fuels → CO2 production that had not reached the atmosphere in millions of years
* coal contains many impurities collected from trapped sediments
* coal combustion → sulfur dioxide (SO2) production + toxic metals (lead, mercury, etc) + PM
* limited through filters, scrubbers, clean coal processes, etc.
* air pollution comes from plant matter: carbon, hydrogen, nitrogen, oxygen, sulfur
* voc - volatile organic compounds
* PM - particulate matter (course & fine particles)
* irritates human body (ie. eyes, nose, throat)
* exacerbate lung conditions and damage
* damage to plant tissue

## 7.2 Photochemical Smog

* VOCs = volatile organic compounds
* can vaporize at room temp
* increased presence in the atmosphere
* ex. formaldehyde, gasoline, trees, plant oils
* formation includes VOCs + sunlight/heat = PANS/O3
* NO + VOC + O2 + UV = O3 + PANs
* ozone peaks during the afternoon after temperature and sun intensity increases
* higher in sunny warmer climates
* higher in the summer
* irritates eyes, nose, throat
* worsens heart/lung conditions
* cause lung cancer from long-term exposure
* tropospheric ozone
* can worsen bronchitis and emphysema
* triggers asthma
* permanent lung damage
* reduced life for plants from lead damage
* reduction of photochemical smog:
* catalytic converters: NO → O2 + N2
* CO + hydrocarbons → CO2 + H2O
* reduce VOCs: pumping gas at night, following gas refueling instructions
* improve fuel efficiency
* reduce the use of internal combustion
* reduce health impacts

## 7.3 Thermal Inversion

* normal conditions: altitude increases = temperature decreases
* reversed in thermal inversion occurring in upper Earth layers
* thermal inversion: hotter air near the surface traps cooler air above
* traps cooler denser air and pollutants (PM)
* more prone in particular geographic areas
* valleys, mountain ranges, coastal winds
* intensified by pollution (ie. industrialization, urbanization, major vehicle usage)
* ex. los angles, mexico city
* \

## 7.4 Atmospheric Pressure & CO2

* natural sources of CO2 emissions: respiration, diffusion, biomass decomposition, wildfires, volcanoes, etc.
* considered fast carbon (not harmful to human health)
* fossil carbon emissions → excess CO2 buildup → ecosystem disruption and health impacts
* particulate matter (PM): particles in the air that can be inhaled
* inhalable → =< 10 microns (0.001 mm)
* 2.5 < x < 10 → upper respiratory concern
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