Criteria Pollutants
These are the six criteria air pollutants identified by the original Clean Air Act for which the EPA must set acceptable limits
What are SO2, NOx, CO, Particulate Matter, Ozone (tropospheric), and Lead?
These are the two primary chemical precursors that react with sunlight and heat to form photochemical smog
What are Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs)?
his phenomenon occurs when a warm layer traps a cooler, denser air mass underneath it
What is a thermal inversion?
This radioactive gas is the second leading cause of lung cancer and enters homes through cracks in the foundation
What is Radon-222?
This device is required on all vehicles made after 1975 to convert NOx, CO, and hydrocarbons into less harmful molecules
What is a catalytic converter?
This metal was a common gasoline additive before being phased out by the EPA starting in 1974 because it is a known neurotoxicant
What is Lead (Pb)?
This secondary pollutant and respiratory irritant typically peaks in the afternoon when sunlight is most direc
What is Tropospheric Ozone (O3)?
Urban areas have higher temperatures than rural areas partly because concrete and asphalt have a lower value of this, meaning they absorb more solar energy
What is albedo?
In developing nations, indoor air pollution is most commonly caused by burning these types of "subsistence" fuels
What is biomass (wood, charcoal, manure)?
This specialized nozzle captures hydrocarbon fumes during refueling and returns them to an underground storage tank
What is a vapor recovery nozzle?
This type of pollutant is emitted directly from a source, such as NOx from a tailpipe or SO2 from a volcanic eruption
What is a primary pollutant?
These carbon-based compounds (like formaldehyde or gasoline) evaporate easily at room temperature and provide the "smell" for many household products
What are Volatile Organic Compounds (VOCs)
This cooling process, which involves water evaporating from plant surfaces, is less common in urban areas due to a lack of vegetation
What is evapotranspiration?
This long, silicate particle was previously used in insulation and is dangerous only when it is disturbed and enters the respiratory tract
hat is asbestos?
These are the two primary pollutants released from coal power plants and vehicles that lead to acid deposition
What are Sulfur Dioxide (SO2) and Nitrogen Oxides (NOx)?
This gas is a product of incomplete combustion and acts as an asphyxiant by displacing oxygen in human blood
What is Carbon Monoxide (CO)?
Ozone formation is driven by sunlight breaking this specific molecule into NO and a free oxygen atom
What is Nitrogen Dioxide (NO2)?
Thermal inversions are environmentally harmful because they prevent this process, which normally disperses pollutants higher into the atmosphere
What is vertical mixing (or convection)?
Radon gas is produced naturally by the decay of this element found in rocks like granite
What is uranium?
Noise pollution can disrupt these three critical animal behaviors, potentially leading to a decline in survival and reproduction
What are communication, migration, and hunting (mating is also acceptable)?
Although not one of the six original criteria pollutants, this gas is regulated as a greenhouse gas because it leads to Earth's warming
What is Carbon Dioxide (CO2)
This color of smog is associated with sulfur dioxide and particulates from coal combustion, while photochemical smog is often called "brown smog"
What is grey smog?
Coastal cities are prone to inversions when this is blown in beneath warmer air above
What is a cold air mass (or ocean breeze)?
This specific VOC is a common adhesive found in particle board, furniture, and carpet glues
What is formaldehyde?
Acidic soil is harmful to plants because it makes toxic metals, such as this one, more soluble in the ground
What is aluminum (or mercury)?