L9_Ozone_AirPollution
Ozone Overview
Ozone (O3) is a significant component of smog and is usually found at ground level.
Bad Ozone: Affects air quality and is not emitted directly into the air but formed through reactions.
Formation of Ground-Level Ozone
Ozone is formed when:
NOx (Nitrogen Oxides)
VOCs (Volatile Organic Compounds)
Heat and Sunlight
Chemical Reaction: NOx + VOC + Heat & Sunlight → Ozone
Major sources of NOx and VOCs come from:
Industrial facilities
Vehicle emissions
Gasoline vapors
Great Smog of London
Occurred in December 1952, significant historical event showcasing air pollution.
Temperature Influence on Ozone
Higher ozone levels observed on warmer days.
Recorded data from Los Angeles reflecting ozone levels in relation to daily maximum temperatures.
Air Quality Index (AQI) for Ozone
Different levels of ozone impact health:
Good: 0 - 54 ppb
Moderate: 55 - 70 ppb
Unhealthy for Sensitive Groups: 71 - 85 ppb
Unhealthy: 86 - 105 ppb
Very Unhealthy: 106+ ppb
The AQI is based on an 8-hour average concentration of ozone (ppb = parts per billion).
Emissions Impacting Ozone Formation
Breakdown of NOx Sources
Major source contributions:
Transportation: 54%
Electric utilities: 22%
Industrial combustion: 14%
Miscellaneous: 2%
Breakdown of VOC Sources
Emissions from:
Solvent use: 29%
On-road vehicles: 28%
Non-road equipment: 19%
Industrial processes: 11%
Other: 13%
Household Contributions to VOCs
Everyday products significantly contributing to VOC emissions include:
Shampoo, hairspray, deodorants, air fresheners, cleaning sprays, laundry detergents, paints, etc.
Surprising impact of these products; household use contributes to 38% of VOC emissions.
Natural Sources of VOCs
Trees produce VOCs:
Various species such as Maple, Oak, and Pine generate isoprene among other compounds impacting air quality.
Ozone Effects on Plants
Ozone exposure can significantly reduce plant growth, affecting:
Photosynthesis due to chlorophyll damage.
Net growth of urban vegetation compared to rural vegetation, influenced by ozone concentration.
Pollution Impact on National Parks
National parks most affected by air pollution:
Sequoia National Park and Kings Canyon National Park received the lowest scores on air quality.
Particulate Matter (PM) Overview
PM2.5: Most concerning pollutant from wildfires, significantly impacts human health.
Sources of particulate matter include:
Wildfires, wind erosion, agriculture, and vehicle emissions.
Tree Mitigation of Air Pollution
Urban trees can remove a fraction of various pollutants like CO, NO2, O3, and PM10 from the atmosphere, but the percentage is relatively low (below 1% for each).
COVID-19 Impact on Air Quality
Notable decreases in pollutant levels observed during the COVID-19 pandemic, comparing March 2020 to averages from 2017-2019 for ozone, carbon monoxide, particulate matter, and nitrogen dioxide.
Summary of Study Points
Understand how ozone is formed, factors affecting its distribution, its impact on plant life, and the significance of PM10 and PM2.5 pollutants, particularly in California.