The built environment around us shapes our lives and influences our health. In this module, we'll explore how built environment from the regional level all the way down to the level of the building that you live, or work, or study in can influence your health both positively and negatively. Let's consider first though different types of built environment aspects that might have an impact on our health. This would include things like, how land is used and transportation availability. It would include things like the design of neighborhoods, and the siting of schools. For example, a very important factor that can help determine the likely outcome of a neighborhood economically is the quality of the school in that neighborhood. Good schools tend to attract economic wealth, bad schools not so much. We can also think about housing quality, contact with nature, street design, public spaces that we have available to us, the amount of density of the population in an area, and things all the way down to the level of sidewalks and paths that'll let you travel throughout the community without getting into a motor vehicle. I'd like to draw your attention to a map here of the city of the Ann Arbor. So this is a land use or land zoning map. In fact, if we were to look at the upper right corner, we would see the School of Public Health, where I am right now. So what do we have on here? Much of the map is occupied by yellow colors, yellow indicating residential zoning. But you'll see the center of the map which corresponds to downtown Ann Arbor tends to have a lot more office space in pink and commercial space in red. Ann Arbor does not have too much industrial space but we do have a fair amount of space dedicated to transportation, and communication, and utilities. We're quite fortunate in Ann Arbor to have a vast number of recreational facilities available to us, those are shown in green on the map. We have a relatively small number of mixed-use zones, meaning we often have residential and commercial uses. This is a best practice from a zoning perspective in that it allows people to live very close to where they might work or shop. Then we're very fortunate to have a very small amount of vacant land. I do want to highlight one feature that university towns like Ann Arbor are often beset with which is the light blue coloration on here, which is public or institutional areas. What you're seeing here is primarily the University of Michigan footprint, and a downside from the city's perspective is at the University of Michigan doesn't pay property taxes in the city. So that's a large amount of real estate that's not basically generating property tax revenue for the city. So let's zoom out to a regional level. We might think for example, the Great Lakes region here in the United States. What are some harmful exposures that might be associated with the built environment? Well, there things we've talked about in other modules in the class; air contaminants, water contaminants, noise, heat, traffic. But of course, we also have to acknowledge the benefits that come with the built environment at a regional level, things like access to a great health care service network, access to an amazing variety of recreational facilities, and ways for us to contact nature. So we do very much struggle with environmental health issues. For example, here in the state of Michigan and in the nearby region, something that's been in the news media recently is public water systems in Michigan that have tested positive for a class of chemicals called PFAS. So here you can see we're just zooming in on the state of Michigan, the purple sites noted on the map here are PFAS sites in the state where there's greater than 70 parts per trillion of this type of chemical in groundwater. You can see also cities are noted here with gray coloration, so we often find the cities and the contaminated groundwater going hand in hand. So this is very much a regional issue of water contamination that the state has to and is trying to address. If we zoom in now to the city level, we have the same harmful exposures possible that we saw at the regional level; air contaminants, water contaminants, noise, heat, traffic, also at a city level we can add things like crime. But we do have very beneficial exposures that result from the built environment in cities, things like opportunities for physical activity, access to healthy food, hopefully good access to health care services and recreational facilities, and again, intentional contact with nature. Thinking about how environmental health and the built environment can be viewed at the city level or giving example of urban heat islands. So you may already be aware that urban regions become warmer than their rural surroundings in high temperature circumstances. So let's take a look at the graph here. On the y-axis of the graph we're looking at increasing temperature, and on the x-axis you can see we have different types of built environments that we might be in for a rural, to suburban, to a more urban residential, to a downtown core area. Then we have a sequence of lines drawn upon these. So I'll highlight the blue lines first. The solid blue line would be the surface temperature, basically the temperature of the ground at night, and you can see the surface temperature tends to be lowest in the rural areas, and rises somewhat to the downtown core and then dropped somewhat again back out to a rural area. The air temperature is very similar to the surface temperature at night. But in the day time, now we're looking at the reddish lines, you can see that the air temperature is relatively flat across all of these areas, but what is different is the surface temperature. So that very topmost line on the graph you can see rises pretty sharply from the rural areas where air temperature and surface temperature are pretty similar to the downtown area where there's a huge increase in surface temperature compared to the air. So as a result, we have all of these hot surfaces of basically man-made built environment in this downtown urban core, and those surfaces tend to hold their heat and release it at night which is why we don't see as much of a decline in the nighttime temperatures in the downtown area as we do for example in the rural areas. So this is a well-known phenomenon of the built environment in cities, and it's one that unfortunately can lead to many fatalities during extreme heat waves. Finally, if we zoom into the building level, we can think about lots of different potentially harmful exposures there. We can have things like high temperature, and high humidity. If we have both of those factors present together, we can get things like you see in the image here, mold. We also have light pollution. We might have indoor air quality issues from environmental tobacco smoke or if we're in a region that burns biomass for energy and heat from smoke from burning those materials. We might get exposed to toxic chemicals or pests and sanitation issues, or our building may be unsafe to begin with and present injury risks or crime hazards. But of course, we also have very beneficial exposures from buildings. The primary one being they provide us shelter from the elements and a safe place to raise and live with our family, and pets, and friends. So just to highlight one potential environmental health issue at the building level. Many people are concerned, I would say perhaps more than they need to be about mold being present in their homes. Mold is of course an aesthetic and certain types of mold can cause allergic reactions, or asthma, or other respiratory complaints, but mold is nevertheless a feature in many homes. So you can see again the right combination of temperature, and humidity can basically encouraged the growth of mold and potential health impacts there. So hopefully, in this module you've gotten a sense that the built environment can influence our health at a very broad scale, perhaps regionally, but all the way down to the individual building that we live or work or study in. All of this built environment is going to increase our chances of having impacted health. What we want to do is design that built environments so the impacts are positive, not negative.
