Yesterday, I examined some of the EPA TAGA data showing a recent dramatic increase in toluene and xylene levels around Pensacola, FL., specifically the area covered by the shaded triangle:
I focused on the dramatic increase in toluene and xylene because the benzene levels were relatively constant.
However, that doesn't mean the benzene levels are irrelevant. If anything, the benzene levels are the most disturbing of the three. The AVERAGE benzene concentration is now 3 times the EPA levels, even higher than previously measured. (warning:PDF)
The 20 microgram/cubic meter limit set by the EPA is equivalent to 6.26 ppb in air. As you can see from the chart, Pensacola's AVERAGE measurable benzene levels are between 15 and 19 ppb. In some places it is much higher.
As far as the EPA is concerned, these numbers are a concern if they persist for a year. From their point of view, that is a reasonable approach. The EPA has to weigh a variety of factors in the process of formulating public policy. It wouldn't be appropriate to label a city as a health hazard for a transient event. However, the damage done to individuals in the interim is not to be ignored. Given the fact this catastrophe is going to be with us for a long time, I think it is worth documenting the benzene levels in and around Pensacola.
Here is a higher resolution map showing specific locations where benzene levels were at least 3 times higher than the level the EPA cites as a potential health concern. The red arrows are from the July 5 data and the blue arrows are from the June 24 data.
The highest levels measured are actually in a Warrington, a town south of Pensacola. The intersection they measured these levels at is shown here:
The EPA, while doing a great job, has to cover a lot of territory. The benefit of their survey approach is to identify potential hot spots. Once those are located, those would be good places to set up stationary monitoring devices to record the benzene exposure residents are going to be experiencing. This is particularly true in areas that are more densely populated. Note the EPA did not take air samples in downtown Pensacola.
In light of the recent news that BP is going to remove the cap this weekend and leave it off for at least a couple of days, we can expect additional high benzene readings downwind. The current Gulf weather forecast for the next few days has the wind blowing from the West at about 10 knots. That is good news for Pensacola, located to the Northeast. However, I would not be surprised if residents along the Gulf coast of Florida, specifically the area west of Ocala, started experiencing something in their air starting Sunday. Here is what I think we will be seeing in the next couple/few days:
UPDATE: Based on recently released satellite radar image from July 7, it appears an oil slick has socked in the Florida panhandle, extending from Mobile Bay to well beyond Panama City. The slick comes right up to the shore, so this may be the source of the volatile organic compounds (VOC) showing up in the EPA data, not VOC originating at ground zero.
Here is the satellite image:
If you overlay the current prevailing winds, it's a good bet that anyone measuring air samples in Panama City right now would see readings comparable to those reported in Pensacola if the offshore oil slick is the source of the air pollution.
The red blob is the approximate location of the oil slick near ground zero. The grey blob is the approximate location of the oil slick along the Florida panhandle. The wind barbs show the current direction and strength of the wind (from the West at about 10 knots). To see the original satellite image, go to Skytruth's site. Considering the local temperatures are in the high eighties, I expect this will be a problem for quite awhile as the VOC blow off the surface.