Editor’s Note: The following press release was issued Tuesday afternoon by the Allegheny County Health Department (ACHD). GASP thanks the department for addressing the H2S and SO2 exceedances publicly - we appreciate the transparency!
The Allegheny County Health Department (ACHD) received three sulfur dioxide (SO2) exceedance alerts from the North Braddock monitoring station in the early morning hours Tuesday.
As part of our ongoing monitoring program, these alerts help inform the ACHD Air Quality team of potential issues in the area so they can further investigate what may be happening.
The alerts went off at 1 am, 2 am and 4 am. Hydrogen sulfide (H2S) and carbon monoxide (CO) were also elevated from their typical levels during this time period.
The one-hour National Ambient Air Quality Standard for SO2 is 0.075 parts per million (ppm). Preliminary numbers show that at from 12 am to 1am SO2 was at 0.083 ppm, from 1am to 2 am SO2 was at 0.116 ppm, and from 3 am to 4 am SO2 was at 0.077 ppm.
H2S levels exceeded the 24-hour state standard of 0.005 ppm and the highest concentration happened from 1 am to 2am at 0.073 ppm. However, the one-hour state standard of 0.100 ppm was not exceeded over that same time period.
While CO did not exceed the federal standard of 35,000 parts per billion (ppb), the highest hourly concentration of CO from 11 pm on February 24 to 6 am on February 25 was 10,978 ppb. The North Braddock monitoring station normally records CO at about 200-400 ppb.
As of 9 am, CO, SO2, and H2S have been measured in low concentrations at the North Braddock monitoring station. ACHD has been in contact with pollution sources in the area to determine whether any local operations could have caused the exceedances. ACHD is currently investigating the issue and will provide additional information as it becomes available.
Residents can view hourly monitored data on the ACHD daily summary (North Braddock is available on p. 76) to see CO, SO2, and H2S concentrations. Hourly readings of H2S levels are also available using the air quality dashboard.
More about SO2:
According to the EPA, the largest source of SO2 in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Smaller sources of SO2 emissions include industrial processes such as extracting metal from ore; natural sources such as volcanoes; and locomotives, ships and other vehicles and heavy equipment that burn fuel with a high sulfur content.
SO2 can affect both health and the environment.
What are the health effects of SO2?
Short-term exposures to SO2 can harm the human respiratory system and make breathing difficult. People with asthma, particularly children, are sensitive to these effects of SO2. Watch for symptoms such as coughing or shortness of breath. These are signs to take it easier.
SO2 emissions that lead to high concentrations of SO2 in the air generally also lead to the formation of other sulfur oxides (SOx). SOx can react with other compounds in the atmosphere to form small particles. These particles contribute to particulate matter (PM) pollution. Small particles may penetrate deeply into the lungs and in sufficient quantity can contribute to health problems.
What are the environmental effects of SO2 and other sulfur oxides?
At high concentrations, gaseous SOx can harm trees and plants by damaging foliage and decreasing growth.
SO2 and other sulfur oxides can contribute to acid rain which can harm sensitive ecosystems.
What is hydrogen sulfide?
Hydrogen sulfide is a flammable, colorless gas that smells like rotten eggs. People usually can smell hydrogen sulfide at low concentrations in air ranging from 0.0005 to 0.3 parts per million (ppm).
How can hydrogen sulfide affect my health?
Studies in humans suggest that the respiratory tract and nervous system are the most sensitive targets of hydrogen sulfide toxicity.
Respiratory distress or arrest has been observed in people exposed to very high concentrations of hydrogen sulfide.
Exposure to low concentrations of hydrogen sulfide may cause irritation to the eyes, nose, or throat or headaches, poor memory, tiredness, and balance problems. It may also cause difficulty in breathing for some asthmatics. Respiratory distress or arrest has been observed in people exposed to very high concentrations of hydrogen sulfide. Brief exposures to high concentrations of hydrogen sulfide can cause loss of consciousness. In most cases, the person appears to regain consciousness without any other effects. However, in some individuals, there may be permanent or long-term effects such as headaches, poor attention span, poor memory, and poor motor function.
What is carbon monoxide?
Carbon monoxide (CO) is a colorless, practically odorless, and tasteless gas or liquid. It results from incomplete oxidation of carbon in combustion.
Health Effects Associated with Carbon Monoxide
At low concentrations:
Fatigue in healthy people.
Chest pain in people with heart disease.
At higher concentrations:
Impaired vision and coordination.
Headaches.
Dizziness.
Confusion.
Nausea.
Can cause flu-like symptoms that clear up after leaving home. Fatal at very high concentrations. Acute effects are due to the formation of carboxyhemoglobin in the blood, which inhibits oxygen intake.
At moderate concentrations, angina, impaired vision, and reduced brain function may result. At higher concentrations, CO exposure can be fatal.
Residents should test Carbon Monoxide detectors to ensure they are working properly and immediately leave if the alarm goes off. After moving to a safer location, call 9-1-1 and report the issue.