The oil spilling into the Gulf, and the dispersants being sprayed on the oil, contain some chemicals that evaporate into the air and could be carried in the wind toward shore. Residents in some of the onshore areas closest to the oil spill have reported odors and symptoms such as headaches, dizziness, nausea, eye irritation, and respiratory problems. The EPA has been responsive to public concerns about hazards in the air, and has set up a network of stationary and mobile monitors along the coastline. Our analysis of the EPA data identifies some levels that could raise health concerns. If the winds shift or the oil moves, we expect to see EPA air monitoring results from other locations. This blog post will be updated regularly with the new EPA data, so bookmark this page and check back here for new information.
The residents and workers in the path of any fumes resulting from the oil spill need access to high quality comprehensive data on the threats in their air. As the winds shift, communities and scientists need to be able to see where the monitors are located, and get rapid and regular updates. Unfortunately, the EPA data are currently being posted with a delay of several days, so we’ll get the information up here as soon as it’s available, and we’re urging EPA to post the data more quickly. Further monitoring of air quality in these areas will be essential to identify threats and protect public health.
Of the pollutants EPA is testing for, the Total VOCs, hydrogen sulfide, benzene and naphthalene are the most worrisome for the health of communities living and working in the areas near the monitors. EPA is providing daily summaries of their monitoring data at various locations for PM, Total VOCs and hydrogen sulfide. They are also providing some limited data on specific VOCs (such as benzene) and some semi-volatile chemicals such as naphthalene.
If you just want the latest updates for your area, skip this section, but if you want to know how we’re interpreting the EPA data, read this next technical bit.
When the volatile chemicals from oil are monitored together as a group they are referred to as total Volatile Organic Compounds (or VOCs). I summarized the health effects of VOCs in a prior blog post. Unfortunately, there are no regulatory standards for ‘safe’ levels of total VOCs in the air; all of the regulatory standards are focused on specific VOCs. OK, so let’s look at specific VOCs: The most worrisome VOC in oil is benzene because it is known to cause leukemia in humans. Unfortunately, since the data reported by EPA sometimes only includes total VOCs, we don’t know what fraction of that number consists of benzene; in fact, there are no data at all (so far) on what fraction of the oil-related VOCs in the Gulf consist of benzene. So in order to put the EPA data into context, we came up with an estimate of what level of total VOCs could exceed regulatory standards for benzene.
Here’s how we made the calculation: Benzene levels in crude oil range up to 1 percent by weight (source: KIRKELEIT et al 2006: Benzene exposure on a Crude Oil Production Vessel). However, benzene would make up a much larger fraction of the VOCs that evaporate off the oil. A National Academy of Sciences (NAS) report cites an estimate that about 40 percent of crude oil evaporates after it is spilled. We divided 40% by total benzene levels in crude oil (1%), to come up with an estimate of 2.5 percent benzene in the VOC fraction. The National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit for benzene is 0.1 (which isn’t necessarily the best benchmark, but it seems to be the best of the options), so any total VOC levels over [0.1 / 0.025] = 4 parts per million (PPM) could present a health concern. EPA seems to be using a cut-off of 10 ppm for their decisions on follow-up sampling, which might be based on a benzene fraction in the VOCs of 1%, which we do not think is sufficiently health-protective. Others could argue that levels of total VOCs under 4 ppm may be hazardous, so it’s clear that this issue is somewhat controversial. Based on this, we recommend the following guidelines for health risk levels from total VOCs:
Another threat to air quality and human health associated with oil spills is hydrogen sulfide. Hydrogen sulfide (H2S) smells like rotten eggs and can irritate the eyes, cause respiratory problems (particularly in individuals with underlying diseases like asthma), and result in nausea, dizziness, confusion and headaches. The EPA reports that a level at which acute effects could occur in sensitive individuals is an average of 0.33 ppm over 8 hours, and the workplace standard is 10 ppm. Based on this, we recommend the following guidelines for health risk levels from hydrogen sulfide:
Benzene is one of the more toxic chemicals in crude oil. It readily evaporates and can enter the air where people can be exposed by breathing it. It is known to cause leukemia in humans, and long-term exposures, even at low levels, can be very hazardous. For this reason, the following regulatory standards have been established:
Naphthalene is another cancer causing chemical in crude oil that can evaporate into the air. The following regulatory standards have been established:
Here’s the summary of the EPA air monitoring data. I’ll be updating this information daily as new information becomes available, so bookmark this blog and check back!
Summary of data prior to May 21, 2010:
Near Venice, LA, the EPA is conducting air quality monitoring at fixed locations and as part of mobile sampling conducted in the TAGA bus. Sampling data from April 28th through May 16th is currently available for five fixed locations for the following pollutants, PM, Total VOCs, hydrogen sulfide, benzene, ethylbenzene, toluene, xylene and naphthalene – although not all locations were monitored every day and not all pollutants were included. Maps of some of the monitoring stations are located on the EPA website. Roughly, these stations are/were located as follows:
EPA has posted sampling results from April 28th through May 16th from the fixed monitoring stations. The daily average one hour measurement ranged from 0.05 to 2.7 ppm at these stations and the maximum levels recorded ranged from 0.1 to 5.91 ppm. During this time period none of the daily average measurements exceeded public health levels of concern.
Air Toxics (benzene and naphthalene)
EPA data on benzene and naphthalene levels is available for the fixed monitoring stations from April 28th through May 12th and just benzene from the mobile TAGA bus from May 5th. The majority of the sampling results for these chemicals at the fixed monitoring sites were below the detectable limit of the instrument, and we do not yet know whether the instruments are sufficiently sensitive to detect levels of concern. However, both chemicals were found in the air during this time period. The highest levels recorded were 0.09 ppm for benzene and 0.003 ppm for naphthalene. Along the TAGA bus route, the benzene levels ranged up to 0.025 ppm. Detectable levels of both benzene and naphthalene were lower than workplace standards and levels where there would be acute health effects. Continued exposures to these chemicals at the higher levels recorded could pose long-term health risks.
EPA has posted sampling results from May 2nd through May 16th from three of the fixed monitoring stations (V02, V03 and V05). The daily average hydrogen sulfide measurements recorded at these stations ranged from undetectable to 0.846 ppm. However, we have learned that some of the instruments EPA is using have limits of detection that are significantly above health-based thresholds, so we are not confident that these results are appropriately capturing levels of concern. The maximum level recorded was 1.2 ppm. The average daily level at two monitoring stations during this time exceeded the EPA threshold where acute symptoms would be expected (0.3 ppm). These measurements were recorded at the following locations on the following days:
Near Chalmette, LA, the EPA is conducting air quality monitoring at fixed locations and as part of mobile sampling conducted in the TAGA bus. Sampling data from May 2nd through May 16th is currently available for five fixed locations for the following pollutants, PM, Total VOCs, benzene, ethylbenzene, toluene, xylene and naphthalene – although not all locations were monitored every day and not all pollutants were included. Maps of some of the monitoring stations are located on the EPA website. Roughly, these stations are/were located as follows:
EPA has posted sampling results from May 2nd through May 16th from the fixed monitoring stations. The daily average one hour measurement ranged from 0.007 to 3.391 ppm at these stations and the maximum levels recorded ranged from 0.094 to 26.6 ppm. During this time period none of the daily average measurements exceeded public health levels of concern.
Air Toxics (benzene and naphthalene)
EPA data on benzene and naphthalene levels is available for the fixed monitoring stations from May2nd through May 13th and just benzene from the mobile TAGA bus monitoring on May 7th. The majority of the sampling results for these chemicals at the fixed monitoring sites were found to be below the detectable limit of the instrument. However, benzene was found in the air during the time period. The highest level recorded was .001 ppm. Along the TAGA bus route, the benzene levels ranged up to 0.012 ppm. Detectable levels of benzene were lower than workplace standards and levels where there would be acute or long-term health effects.
Levels of hydrogen sulfide at the monitoring locations near Chalmette are not currently available from EPA.
This post originally appeared on NRDC's Switchboard blog.