 So today we're going to talk a little bit about air pollution and some of the effects that it has, its environmental effects. Air pollution and water pollution being sort of two of our major categories when we're studying environmental science and when we're looking for things to clean up through environmental engineering. So there are many sources of air pollution. Many of these sources are what we call anthropogenic, which means that they're generated by the activities of man, but not all of them are. A number of the sources can include just the normal sort of physical and chemical processes that incur naturally either from natural biology or from the activity of things like volcanoes or the chemical processes, the interface between the ocean and the atmosphere, for example, can cause a lot of chemical changes in the environment. But again, the majority of things that we're concerned about are things that are anthropogenic. In other words, man-made pollutants. And generally those pollutants will be created in one location, then they will be transported through the motion of the air and end up somewhere else. So there is actually a cycle for these pollutants in the same way that there is a water cycle or a carbon cycle. There are sort of cycles for pollutants, how they enter the atmosphere and then how they are in other sort of conditions in the water system or even in the soil, et cetera. So we're going to talk about a bunch of different types. Here are some of the primary types of air pollutants and they're different, the list of their different sources. Again, you'll see many of these. Their sources are things like industry and another big source is vehicles. Our use of automobiles contributes to major sources. So vehicles being some of the major sources here. As we continue to increase our use of vehicles that burn fossil fuels, we tend to continue to contribute to air pollution. All of these have different sort of health effects as well as effects on the natural environment. So we're concerned both with their effects on humans and their effects on other aspects of the environment. So let's talk first of all about a term called smog. Smog is kind of a mix, well it is a mix of the two terms, smoke and fog, where smoke is particulate matter, soot and soil and ash and other things that are created usually by human activity. And fog is the natural sort of accumulation of water in the atmosphere when it gets saturated. And basically once you've created smog, you will have the combination of water mixed in with various chemicals which will sort of increase chemical reactions and that either creates additional particles or makes the particles that currently exist in the smoke, it changes their chemistry. So when we talk about particles it's sort of the first thing we talk about air pollution are very very small fine particles of well what are actually solid. They're not actually gashes formed, they're solid but they're light enough or small enough that if they get kicked up or stirred up or pushed into the atmosphere then they'll actually stay in the atmosphere for a period in time. They are usually heavier than air which means that they'll usually eventually over time settle out but lots of activity in the air, lots of stirring or mixing can kick them back up into the atmosphere again. The particles can be harmful themselves. You don't want chunks of dirt in your lungs and in fact your body is sort of designed to prevent some particles from getting in there through your the mucous membranes in your nose and in your throat etc but large amounts of them can be harmful in themselves but in addition these particles also tend to harbor places where chemicals can attach to and then those chemicals get delivered into the lungs and into the body. Also biological pathogens can sometimes be attached to particles although this is less frequent when we're talking about air pollution. Now there's a concept here called an inversion. It turns out that the layers of the atmosphere or the atmosphere itself can sort of be separated into layers of four different layers and these layers are primarily based on differences in temperature. Well actually differences in how the temperature is changing. For our lowest layer in the troposphere you actually have a cooling effect. You notice if you climb a mountain or the higher you go the cooler you get the further you get away from the earth which is a heating source and things cool down but once you get to a certain point you get to an area in the atmosphere where some of the air is being heated up by the interaction of light with particles there including things like carbon dioxide etc and that leads to a heating effect in that area which means that there is a layer where we go from gradually cooling to gradually heating. That's the stratosphere and what happens there is in between there in that area of cooling that sort of warmer air that's above the colder air prevents some of the motion the vertical motion or changes how things are moving prevents some of the vertical motion that would normally occur with less density as you as things would rise. So it tends to trap atmospheric particles trapping air and atmospheric particles underneath it. Well that inversion those will change depending on sort of your weather the depending on the weather in the area the inversion may be higher or lower okay and so as you can see like the winter sun supplies a little less warmth the warm air kind of caps things in okay and you tend to trap pollutants inside and those pollutants can be further trapped by the existence of things like mountains so just the sort of physical and temperature nature of the atmosphere can sort of create a container and or sort of areas to hold pollutants in and they can also create areas that end up guiding the pollutants that they're pushed in certain directions by the motion of the wind. So some of the different types of compounds we might be considered out first of all sulfur compounds now sulfur exists naturally it is something that's emitted by things like volcanoes but generally it's something that is a result of combustion and when we combust fossil fuels both for industry and for vehicles we create part of the remnants that are left behind are things like sulfur dioxide sulfur trioxide basically sulfur mixed with oxygen and different sort of particular matter okay well when that those sulfates actually interact with hydrogen and oxygen there's a tendency for things to break under different energy and leave relatively acidic conditions as a result so sulfur is a pretty big contributor to things like acid rain you'll notice here that there's sort of a number of a list here of different air pollution that comes from power plants of which sulfur dioxide 60 percent of it comes from the power plants so some of the effects of things like sulfur in humans it basically affects respiration to some degree and it's also been sort of connected to things like cancer and heart disease in the environment it affects it's these pictures here of something of acid rain as we've talked about it'll change it'll sort of acidify the water as it falls from the sky okay which then inhibits aquatic species and also has effects on forests if they're if they're subjected to significant amounts so in this case it's sort of a connection between air quality and water quality some of the ways that we can handle that is that we can require processes chemical processes that before we vent out the waste products the waste air products from burning things we can actually use what are called scrubbers we have different technologies that will allow us to sort of mix in in this case there's things like a limestone slurry basically that's a mixture of lime and water that sort of as it falls through it kind of mixes and gives the sulfur compounds an opportunity to react before they're released into the main chimney stack and then into the atmosphere so we have methods of sort of cleaning things out and then we end up with different solid products that can either be used or disposed of in a different fashion there are other sort of technologies that we can use to do this we can filter using actual physical bags to sort of filter through things and capture things and there are also other ways that we can use sort of electricity and electrostatics to take advantage of the fact that sulfates tend to have charges and will interact to remove the sulfates from the from the environment okay one of the things you'll actually notice is there have been some rules that have been passed to change the amount of sulfur before you burn the fuel that you actually do some things in the processing that remove some of the sulfur from the fuels and that has been very helpful and reducing sulfur content in the atmosphere as you can see over time here actually I believe that's a plot of the restrictions on fuels so another one nitrogen nitrogen is actually sort of key in is another key sort of environmental pollutant primarily because it's an available nutrient so it actually changes the nutrient balance and as we talked about in the case of water pollution if you end up with excess nitrogen in your water supply it actually adds nutrients that allow that that imbalance your biological systems and cause for blooms in algal growth etc for example okay we can reduce nitrogen oxides it's pretty standard there are catalytic converters that are on your car and things like that we can actually make sure that when we're combusting things we actually provide enough extra heat or energy to combust things completely and remove all the energy and in doing so that will generally result in better results as far as the how the pollution is distributed notice for example in this picture here you have particular compounds that are not completely combusted but if we provide extra heat and some catalysts what we can actually do is result in output that is more benign particulate matter basically stands for anything that's sort of solid pieces and usually the way we classify particulate matter is based on size you can see here we have a range of sizes all these sizes being in microns which is micrometers or 10 to the negative 6 meters okay um and they can reduce in size and the smaller they are the further they go down into your lungs and throat again our biology is designed to capture some particles but the smaller they are the more likely it is that they're going to get in depth further and further into the lungs and end up into the small air sacs or the bronchi in your uh in your lungs if they end up there your body can process them but they can often cause irritation and blockage particularly in people who already have some sort of problems biological problems with their lungs and or their other pulmonary capacity so how can we reduce particulate matter well there are practices that we can do when we're dealing with agriculture and construction notice usually when we're digging into the soil we're going to tend to stir up things well if you can do that digging while wetting things down or you can use certain practices that don't sort of stir things up you can use certain crops that prevent fields from being sort of bare similarly when you're doing construction you can do things that sort of cover up and prevent direct exposure of open soil to the air and that can sort of reduce your particulate matter we can also further treat combustion exhaust okay and control the sources of different things to reduce the particular matter that's in the air in particular things like their regulations on burning trash and on the technology behind wood burning stoves that if you buy a particular stove there are ways that you can go about making sure that you burn it correctly and therefore reduce some of the particulate matter that comes out and when you think about smoke smoke is actually where we can visualize particulate matter when you see the sort of gray or black or white sort of haze that comes out it's a combination sometimes of steam but also basically a high density of particulate matter is actually visible as smoke mercury is another pollutant that sort of gets mixed in part of burning processes okay and emissions um and then mercury sort of ends up in our various systems and mercury by itself is actually again it's a type of poison that or a toxic substance that accumulates over time so large amounts of mercury can sort of accumulate into biological systems lead again being another another chemical that's considered in air quality something that we measure that's definitely been attributed to health problems particularly in the development of younger children uh infants and younger children and then another one in our list is something called volatile organic compounds or vocs basically these are groups of compounds that are primarily carbon based and volatile means that they tend to evaporate at low i mean at relatively low temperatures so in sort of our standard normal temperatures they evaporate things like gasoline for example you know that as soon as you spill gasoline you'll immediately smell it and it'll evaporate very quickly that's an example of something like a volatile organic compound okay we have many many uh ways that we produce these but again primarily they're from the combustion of fuel and then our industrial and vehicle processes so one of the things we do one of our purposes of sort of is we have the EPA and other groups monitor the presence of these different contaminants and you'll notice there is a series here six different categories but include particulate matter that's the PM here okay carbon monoxide sulfur dioxide ozone and nitrogen oxide um nitrous i'm forgetting which NO2 is um but we have a series of those that are sort of that we measure and keep track of the different pollutant concentrations and each of those concentrations if they reach a particular value they contribute to what's called an air quality index they give a score depending on how much there is a one or another for example you might have a certain amount of particulate matter of a certain size over 24 hours but you might have a lower amount of carbon monoxide etc so you'll have some different amounts each of those contribute to the air quality index which is the score from zero up to as high as 500 but notice once you get above 200 you get to a place where you're considered very unhealthy and this index is mostly meant to help communicate to the general public recommendations about behavior for how they should behave if they want to sort of maintain their health or to be to to best behave when the air quality is very poor very often you might just ignore the air quality but you'll notice on certain days that you might see some information about the air quality being poor or in one of these sort of categories they use colors to sort of represent that a green color represent hey not a bad day you can do normal activities whereas you get to the red or the purple color it generally indicates that the air quality is unhealthy for breathing so how you monitor sort of monitor your your behavior then is to you kind of consider what happens depending on what risk you're at if you're already suffering from some sort of reduced breathing capacity then you might need to on very even relatively low risk day well moderate risk days you might consider not planning on going for a run or doing something that might require you to breathe at a high rate and therefore bring in more pollutant than you would normally notice once you get to the very high risk level then everybody is sort of recommended to maybe reduce the amount of activity that they do and this air quality index is something that we use pretty regularly that is sort of maintained the EPA will report on it and you can even consider as sort of a weather map so you can look and see and find that information from day to day particularly when you know in North Carolina for example one very very hot days they will often have poor air quality and there'll be some indications of that other cities are known for having particularly poor air quality Beijing is one of them which is currently growing going through a particular amount of growth and a large amount of industry that leads to high and poor air quality so those are some of the pieces of the the pieces the different pollutants that we consider as part of our air quality and a little bit of a discussion about what it means to have poor air quality and air pollution