Air quality in Philly neighborhoods is mostly determined by proximity (how close are you to some of our city’s largest polluters). It is reasonable to believe that distance from where you are to the Sunoco refinery or I-95 has a significant impact on the quality of air you breathe. But, as I mentioned before, the current air quality monitoring network doesn’t give us a clear picture of this. This isn’t true for the whole of the city, as air pollution from places outside of Philadelphia can travel into the city by way of large-scale air currents. The heavy pollution from Beijing hanging in the Los Angeles basin is a good example of this type of air quality travel. At the neighborhood level, though, what you are close to means a lot for what you breathe.
Above is a land-use map of Philadelphia I made depicting the variety of different uses in the city. For those of us that spend quite a bit of time looking at maps and thinking about space in Philadelphia, it isn’t much of a surprise: a long stretch on industrial use on the western edge of the Delaware river that snakes down around the expanding southport; dense commercial and transportation use in our very own central business district, center city; a sea of yellow and orange residential and vacant land in our urban neighborhoods; and large tracts of contiguous industrial and transportation in the southwest marking the space of food terminals, the refinery, and our somewhat international airport. The pie chart of land use by square mile included here shows that just over half of land in the city is taken up by residences and transportation alone.
It is hard to say exactly how land-use in a neighborhood effects air quality, but one study has shown that proximity to a port, traffic intensity, distance to road, and residential density can explain the majority of air pollution in an area. This means that the denser your neighborhood and the closer it is to transportation, the more likely you are to have high levels of particulate matter. Another study, carried out in NYC, showed similar results, but noted that adding industrial land use to the equation helped improve predictions of where particulate matter is most concentrated.
I’ve highlighted a few Philadelphia neighborhoods (Port Richmond, Bridesburg, Center City West) to show some of the differences in land use across the city. A note on transportation: street grids take up a deceptive amount of space, and they account for far more actual space than they appear to on the map. Keeping this in mind will help explain some of the massive amounts of land used for transportation in the city. It is also a reminder of the ubiquity of our transportations networks. Gas consuming, particulate producing, mobile combustion machines are everywhere. Of course, these maps don’t show traffic congestion at all (that is for a later post), only the roads they have potential to move through.
Above is a map center city west with a breakdown of land-use distribution in the area. These maps don’t give us a perfectly clear picture of how land-use impacts air quality, but they can help us make some good descriptions of where they are likely to be. For example, taking a look at the Port Richmond/Bridesburg area, we might be able to guess a couple things about air quality in the neighborhoods. These neighborhoods are a small peninsula in a sea of transportation and industry. A major highway interchange flanks all sides of this two-part neighborhood area, concentrating a large transportation hub between both places. A fat, gray arc rests between neighborhoods showing the concentration of transportation between the port and the adjacent industrial areas. Most of the industrial land-use is clustered in southwest Philadelphia and along the Delaware, albeit with a peppering of concentrations in the northeast, but Port Richmond/Bridesburg is uniquely nestled in a dense concentration of transportation and industry.
This might not be surprising, but it does give us a general idea of where we should be looking to monitor and change air quality in the city. While Center City West appears to have high concentrations of transportation land-use, it is important to remember that these streets, while everywhere, are not always full. This is not the case for our not-so-sleepy port neighborhoods. Land-use maps only tell us so much, but they are a good visualization of where all that invisible dust is likely to be concentrated.