Photochemical Smog, PM and Carbon Dioxide Flashcards
How does photochemical smog form?
Photochemical smog is formed when nitrogen oxides & volatile organic hydrocarbons react with heat & sunlight to produce a variety of pollutants
What factors contribute to the formation of photochemical smog? Where are large quantities of photochemical smog most likely to be found?
- Nitrogen oxide is produced early in the day.
- Volatile Organic Compounds (VOCs) (such as formaldehyde & gasoline) evaporate or sublimate at room temperature
- Photochemical smog often forms in urban areas because of the large number of motor vehicles there
Effects of Photochemical Smog
- Eye irritation
- Can worsen bronchitis & emphysema
- Can trigger asthma
- Causes permanent damage to lung tissue
What are examples of VOCs and how they’re formed naturally?
Anthropogenic - Formaldehyde (used in many interior materials) - Gasoline Natural Sources - Trees - Many plant oils - essential oils
PANs (Peroxyacetyl nitrates)
a secondary pollutant that damages plant tissue
What are the secondary pollutants of photochemical smog?
- Ozone
- PANs (Peroxyacyl nitrates)
- Aldehydes (category of VOCs)
- HNO3 (nitric acid)
How does ozone form both with and without VOCs and how do the processes differ?
- In absence of VOCs, ozone will form during daylight hours and break down after sunlight.
- In the presence of VOCs, ozone will form during daylight hours, VOCs then combine with nitrogen oxides to form photochemical oxidants, reducing the amount of ozone that will break down later & contributes to prolonged periods of photochemical smog
What factors affect the formation of ozone?
Timing
- Nitrogen oxide is produced early in the day
(especially during morning rush hour + places with lots of cars)
- Ozone concentrations peak in the afternoon
- Increased sun intensity & temperatures
Location & Seasonality
- Ozone levels are higher in sunny warm climates
- Ozone levels are higher in summer
What are the effects of tropospheric ozone on the environment?
- enters plants through stomata & burns plant tissue, leading to leaf damage & reduced survival
How do catalytic converters work?
- Convert NO into O2 & N2
- CO & hydrocarbons react to produce CO2 & H2O
What are ways to reduce photochemical smog and its harmful effects?
Reduce NO - Catalytic converters - Enforce emission testing and standards for vehicles Reduce VOCs - Pump gas at night - Follow gasoline refueling instructions for efficient vapor recovery, be careful not to spill fuel, & always tighten your gas cap securely Improve your fuel efficiency. - Keep engines properly tuned. - Make sure tires are properly inflated. Reduce the use of internal combustion. - make fewer trips, bike, or walk - use public transportation or carpool - avoid idling your engine* - this is illegal in NJ!!! Reduce health impacts - Minimize outdoor activities in late afternoons in summer - Wear a mask
What are some natural causes of Carbon Dioxide?
- (naturally) respiration, decomposition, & volcanic eruptions, wildfires
Why is CO considered an air pollutant even though it is naturally found?
- The natural carbon cycle is fast and uses “modern” carbon (while it produces CO2, it also serves as a sink for CO2) but anthropogenic sources add “ancient” and excess CO2 into the process that has harmful effects on the environment/human health
Particulate matter (PM)
Solid or liquid particles suspended in air
What is particulate matter size measured in? What is the standard that decides if it is an upper or lower respiratory concern?
- Particulate matter that is under 10 microns (1 micron = 0.001 milimeter) can be inhaled and thus a concern
PM10 - between 2.5 (0.0025mm) & 10 (0.01mm) microns in diameter - Upper respiratory concern
PM2.5 - under 2.5 microns in diameter - Lower respiratory concern
