According to a new study, the chemicals that spewed into the Gulf of Mexico from the BP Oil Spill set off a complex chain of chemical reactions forming air pollution aerosols. Unfortunately these aerosols weren’t adequately monitored for at the time of the spill. While this study did not look at the impacts of this pollution on the clean-up workers or onshore communities, it raises important questions about what Gulf communities were exposed to during the oil spill and shows the need for improved air quality monitoring.
During the oil spill, clean-up workers and coastal communities reported odors and respiratory symptoms linked to winds coming off the oil slick. On shore and off shore air quality monitoring efforts failed to definitely identify the culprit causing these complaints. See my previous blog for more information on the gaps in the monitoring network. The findings of this new study suggest that part of the answer to this puzzle may have been the creation of tiny particles, called organic aerosols, formed when the chemicals in the oil interacted with the air over the oil slick. These particles, less than one micron in diameter, contribute to the poor air quality experienced in many cities and have been linked to respiratory effects, particularly for vulnerable populations.
The study, published last week, in the journal Science, analyzed data taken from airplane flights over the Gulf in June 2010 while the oil was gushing to the surface. The researchers combined these measurements with analysis of the make-up of the oil and modeling of how the compounds in the oil interacted with the water and the air to paint a picture of the chemical processes that transformed the chemicals in the oil into tiny particles that were carried in the air towards the shore. The the air over the oil slick, as expected, contained a narrow band of volatile organic compounds (VOCs). However, there was also a much larger cloud of small aerosol particles. These small particles formed when the compounds which evaporate more slowly (intermediate- and semi-volatile compounds) spread out on the surface of the water and interacted with the air. Clean-up workers in the offshore environment likely inhaled this pollution, and coastal communities may have also been impacted.
Limited monitoring of these particles was performed during the oil spill, particularly offshore where the health impacts would have been the greatest. On shore, the lack of comprehensive air quality monitoring infrastructure in coastal Louisiana - ground zero for the plume documented in this study - limited the ability to detect the impacts of this contamination. The monitoring equipment did not capture spikes of pollution which would have been carried by onshore breezes.
This study highlights the need for more comprehensive air monitoring for workers and impacted communities in the face of oil spills where the air can hold more hazards than previously known.