Missouri Department of Natural Resources

DHSS review of air monitoring data from the Bridgeton Landfill area, April 23 – May 3, 2013 –The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill between April 23 and May 3, 2013.  On April 23, DNR began routine, twice daily, surveillance of hydrogen sulfide, benzene, and odor levels around the entire periphery of the landfill.  In addition, DNR has provided continuous monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, and total volatile organic compounds (VOCs) at three fixed locations.  DHSS has reviewed both sets of data to identify potential public health concerns.

Reduced Sulfur Compounds
DNR monitors intermittently detected reduced sulfur compounds at two of the monitoring locations, south and west of the landfill, particularly during periods of moderate to strong odors.  While average concentrations exceeded acute, short-term health-based guidelines for hydrogen sulfide on several occasions, the compounds being detected were not primarily hydrogen sulfide but were other reduced sulfur compounds.  In fact, all readings with the Jerome meter, which specifically detects hydrogen sulfide only, were well below acute levels of public health concern.  Based on recent lab analysis, the primary reduced sulfur compound in the landfill gas is a compound with similar strong “rotten egg” odor, but much lower toxicity.  Given this information, it is unlikely that reduced sulfur concentrations were above a level of public health concern during this time period, even though odors were often strong.

Sulfur Dioxide
Concentrations of sulfur dioxide continued to exceed health-based guidelines for short-term exposure at the monitoring location west of the landfill property line, near the Metropolitan Sewer District (MSD) lift station.  Sewer gas from the lift station may have contributed to the sulfur dioxide readings at this location.  On April 30, hourly average sulfur dioxide concentrations detected at the monitoring location south of the landfill also exceeded acute guidelines.  While exposure to sulfur dioxide at these concentrations may cause short-term symptoms, considerable dispersion is expected to reduce potential exposure levels at nearby residential areas.  Sulfur dioxide concentrations did not approach levels that could result in more serious short-term or long-lasting effects.

Odors
Strong odors were identified at some surveillance locations around the landfill on a daily basis, generally depending on the wind direction.  Symptoms associated with exposure to strong odors include headache, nausea, and fatigue.  During periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms.  Symptoms generally associated with strong odors typically disappear once the odors dissipate.

Benzene, Total VOCs and Carbon Monoxide
Benzene was not detected in ambient air at any of the surveillance locations around the landfill.  Hourly average concentrations of carbon monoxide and total VOCs did not exceed levels of health concern.

DHSS review of air monitoring data from the Bridgeton Landfill area, March 16 - April 23, The Department of Health and Senior Services (DHSS) has reviewed air quality screening data collected by the Department of Natural Resources (DNR) at Bridgeton Landfill between March 16 and April 23, 2013.  DNR has performed continuous air monitoring at three locations near the landfill since mid-February.  DHSS reviews the monitoring data to identify potential public health concerns associated with exposure to hydrogen sulfide, sulfur dioxide, total volatile organic compounds (VOCs) and carbon monoxide (CO) in ambient air near the landfill.

Hydrogen Sulfide
In late April, DNR deployed a new piece of equipment, a Jerome meter, which has the capability of detecting hydrogen sulfide levels separate from levels of reduced sulfur compounds. The AreaRAE monitor, which has been in use since February, detects hydrogen sulfide and other reduced sulfur compounds but does not distinguish between the two. The Jerome meter and the AreaRAE monitor were placed together during a period of high odor. The Jerome meter detected hydrogen sulfide at less than ten parts per billion which is below a level of health concern. At the same time, the AreaRAE monitor detected a mixture of hydrogen sulfide and reduced sulfur compounds at several hundred parts per billion. This level is exceeds acute health-based guidelines for hydrogen sulfide alone; however, previous lab analysis showed that the primary reduced sulfur compound in the landfill gas is a compound with similar odor to hydrogen sulfide but lower toxicity.

Sulfur Dioxide
Moderate concentrations of sulfur dioxide were observed intermittently at two of the AreaRAE monitoring locations, west and south of the landfill. Hourly average monitor readings exceeded health-based guidelines for short-term exposure on March 16 through April 2 and April 23 at the monitoring location west of the landfill, next to the Metropolitan Sewer District (MSD) lift station. Sewer gas from the lift station may have contributed to the sulfur dioxide readings at this location.  Sporadic sulfur dioxide detections occurred on April 7, 8, and 22 at the monitor south of the landfill. Individuals near these locations on those dates may have experienced transient symptoms such as cough and/or irritation of the eyes, nose, or throat.  Sensitive individuals, such as asthmatics or those with other chronic respiratory conditions, are more likely to have experienced symptoms; however, sulfur dioxide concentrations did not approach levels that could result in more serious short-term or long-lasting effects.

Volatile Organic Compounds and Carbon Monoxide
The total VOC data from the AreaRAE monitors do not specify different compounds, and the results of total VOC monitoring were inconclusive due to insufficient data quality. Because benzene has been the primary VOC of public health concern, DNR has requested the subcontractor use an UltraRAE benzene detector going forward for routine monitoring around the landfill to address this issue. DNR is working with DHSS to provide time sensitive data for use in evaluations and future recommendations. In addition, DNR should continue regular air sampling for laboratory analysis of individual VOCs and other compounds. Hourly average CO concentrations were below levels of health concern in all areas.

Recommendations
DHSS continues to recommend that during periods of objectionable odor, sensitive individuals should stay indoors as much as possible, avoid outdoor exercise, and seek medical advice for any acute symptoms.  DNR should continue regular air sampling, as recommended by DHSS. 

On March 19, DHSS review of air monitoring data from the Bridgeton Landfill area, February 13 – March 15, 2013, the Department of Health and Senior Services (DHSS) has reviewed the air quality screening data from the Department of Natural Resources (DNR) for the Bridgeton Landfill for the period of February 13 through March 15, 2013.  DHSS previously recommended long-term air monitoring, which DNR provided with this screening data.  The air monitoring was carried out continuously, 24 hours a day, at three monitoring locations near the landfill. 

DHSS reviewed the levels of carbon monoxide (CO), total volatile organic compounds (VOCs), hydrogen sulfide and sulfur dioxide (SO2). The average CO, VOC and SO2 levels were not identified at concentrations of health concern.

In the case of hydrogen sulfide, the screening data identified a potential public health concern that warranted further evaluation. For a combined total of three to four hours, on the afternoons of February 14, 23 and 24, average concentrations of hydrogen sulfide at the air monitoring location near Hussmann Corporation (12999 St. Charles Rock Road) exceeded a health-based comparison value for short term exposures (1 to 14 days) but were not in excess of public health protection guidelines for exposures lasting less than 24 hours.  Although it is not possible to draw definitive conclusions from this screening data, DHSS deems that additional monitoring or other actions are warranted.

Exposure to elevated levels of hydrogen sulfide can cause headache, irritation to eyes, nose or throat, and may cause difficulty breathing especially for persons with asthma or other chronic respiratory conditions.  In fact, any intense odors can have public health effects on both quality of life and well-being, particularly for sensitive individuals.  Symptoms generally associated with offensive odors typically disappear once the odors dissipate. 

DNR will continue increased air sampling, as recommended by DHSS, to allow for more definite conclusions to be drawn regarding any potential health risks of public exposure to chemicals in the landfill gases. 

During periods of objectionable odor, sensitive individuals and persons with chronic respiratory diseases should limit time spent outdoors and seek medical advice for any acute symptoms. 

DHSS review data from March 13 air sampling at Bridgeton Landfill – the Missouri Department of Health and Senior Services (DHSS) has reviewed the air sample data from the March 13, 2013 sampling event at Bridgeton Landfill.   Timed (5-hour) samples were collected from two downwind locations, during a period of medium-strong odor emissions, between the landfill and a residential area.  One sample was collected in an upwind location.

DHSS specifically reviewed the concentrations of volatile organic compounds (VOCs) in air samples.   Of the 62 VOCs targeted in the air sample analysis, 8 VOCs were detected in the downwind samples.  None of these VOC concentrations exceeded appropriate health-based screening values for either short-term or chronic exposure in ambient air.  As a result, DHSS did not identify VOC concentrations of public health concern in the data from this sampling event.  DHSS recommends continued air monitoring and sampling to identify any potential health risks of public exposure to landfill gases.

DHSS review of air monitoring data from the Bridgeton Landfill area from Feb. 15 sampling event, the Department of Health and Senior Services reviewed the air sample data and concentrations of volatile organic compounds (VOCs) in the ambient air samples and found that the analyzed gas concentrations did not exceed a level of concern for public health.

Of the 62 VOCs targeted in the analysis, 12 VOCs were detected in downwind samples. Of the 12 VOCs detected, only benzene in the sample collected near the landfill property line exceeded a health-based screening level for chronic (>1 year) exposure. A lower benzene concentration was detected at the sampling location near the residential area, but did not exceed the screening levels for chronic exposure. None of the detected VOCs exceeded health-based screening levels for acute (<14 days) or intermediate (2 weeks – 1 year) exposure.

DHSS review of air monitoring data from the Bridgeton Landfill area from Feb. 4-5 sampling event, the Department of Health and Senior Services reviewed the air sample data including the concentrations of 62 volatile organic compounds and 12 aldehydes in the air. Department of Health and Senior Services analysis found the analyzed gas concentrations did not exceed a level of concern for public health.

Samples collected in a nearby residential area also showed no chemicals detected above a level of public health concern. Samples were also collected along the landfill property line to capture the worst-case exposure scenario. Department of Health and Senior Services did identify a short-term benzene concentration in one sample near the landfill property line that was slightly above a conservative health-protective screening level for long-term (>1 year) residential exposure. However, this momentary sample result was two to three times less than health-protective screening levels for shorter term exposures.  A significant decrease in landfill gas chemical concentrations was observed from the property line to the residential neighborhood, apparently due to dispersion of the landfill gases in ambient air.

DHSS review of air monitoring data from the Bridgeton Landfill area from the Feb. 2 sampling event, the Department of Health and Senior Services reviewed the air quality screening data including levels of carbon monoxide, total volatile organic compounds and hydrogen sulfide. A review of the air quality data found that gas concentrations did not exceed a level of concern for public health. Department of Health and Senior Services also reviewed the gamma radiation readings detected by the Department of Natural Resources and collected samples from the air to provide additional details. The real time radiation sampling by DNR did not detect gamma radiation rates outside of normal levels. Laboratory analysis of the Department of Health and Senior Services samples by two different laboratories confirmed that no radioactivity was detected above normal background levels.