Pragmatic Approach to the Issue of Hydrogen Sulfide in Drywalls
The discourse relative to the legal responsibility for using defective drywall and to the nature of the chemicals which emit the hydrogen sulfide will undoubtedly continue for a long time. However, the basic fact that hydrogen sulfide is toxic and exposure to it is harmful in not questioned. Therefore, it is incumbent on all the responsible parties to immediately stop the exposure of people to HYDROGEN SULFIDE to prevent recurring harm to their health and damage to their property.
The toxicity of hydrogen sulfide is manifested in two different mechanisms: A. HYDROGEN SULFIDE reacts with the iron in the blood and depletes it and thus can have negative impact on the respiratory function of the body and the transfer of oxygen. This effect is more dangerous when the exposed people are old, children or infants, pregnant woman and people with respiratory issues, and, B. Chronic exposure even to minute concentrations of HYDROGEN SULFIDE (and sulfur oxides) reduce the resistance of the lungs to viral and bacterial attacks and thus will increase the susceptibility of exposed people to contracting various infectious diseases not normally associated with exposure to inorganic toxic gas such as HYDROGEN SULFIDE or sulfur oxides.
With this philosophy in mind, it is imperative that the same steps followed by Hazmat teams, Dept. of Defense personnel and Industrial Hygienists will be followed in this case too. These steps are:
- Measure the CONCENTRATION of HYDROGEN SULFIDE in the house and QUICKLY IDENTIFY the houses where the dwellers are exposed to dangerous concentrations of HYDROGEN SULFIDE.
- QUICKLY take protective measures to STOP the DANGEROUS EXPOSURE and prevent additional damage to the inhabitants.
- VERIFY that the danger has been eliminated and that the SOURCE of HYDROGEN SULFIDE was removed.
Methods of Measuring HYDROGEN SULFIDE in Houses
The concentration of HYDROGEN SULFIDE is not constant and varies with the operation of the air conditioner, the frequency of opening and closing of doors and windows, the presence of open sources of HYDROGEN SULFIDE such as rotting garbage or sewer lines. A proper measure of exposure to HYDROGEN SULFIDE in a house is the average concentration that a dweller breaths while living in the house.
Two different methods have been used to measure the HS concentration:
- Assessment of the concentration based on a DOSIMETRIC measurement over a period of time, (DOS), and,
- Spot measurement, (SM), of the concentration using a HYDROGEN SULFIDE detector.
The DOS method gives the average HYDROGEN SULFIDE concentration breathed over the measurement period, typically 3-5 days. The SM gives the HYDROGEN SULFIDE concentration at the location of the measurement at that instant. The underling assumption is that this spot value represents the average concentration. Unfortunately, SM methods are prone to give a large error since the mere presence and movement of the people who carry the measuring device creates air movements which are not normally associated with the dwellers breathing the air.
A Low-Cost Dosimetric Method for Measuring HYDROGEN SULFIDE Concentration
The easiest and cheapest way to measure the average concentration of HYDROGEN SULFIDE in a house involves using the low-cost dosimeters offered by ChemSee. This method was developed originally for the US Department of Defense and thousands of dosimeters were sold to the US Marines during the first Gulf War. The dosimeter is a small card which changes its color when exposed to HYDROGEN SULFIDE. The extent of color that develops is related to the EXPOSURE TIME, in hours and the AVERAGE CONCENTRATION, in parts per millions, (PPM), or parts per billions, PPB.
USE INSTRUCTIONS OF THE HYDROGEN SULFIDE DOSIMETERS
To use the dosimeter, all you need is to take the dosimeter from the envelop it came in and place it in the location you want to measure the HYDROGEN SULFIDE. Let the dosimeter stay there the appropriate length of time, and observe the color formed AT THE END OF THE REQUIRED TIME. If the house is occupied and/or uses an air conditioner, let the card stay in the test area FIVE days. If the house is vacant and usesno air conditioner, let the dosimeter stay in the test area THREE days. Note that the card has to be placed with the side shown DOWN. The back side does NOT have the colored circles printed on it. Mark the DOSIMETER LOCATION and the START and END of the exposure test. If a visible color is seen, the HYDROGEN SULFIDE concentration most likely exceeds the allowed level for normal civilian dwelling. In all cases, even if no color is visible to the naked eyes, the user is advised to place the card back in the envelop it came in and send it to the manufacturer for electronic reading. Make sure you write the date and time of the beginning and end of the exposure time and the test location.