Microsoft Word Marcellus Radon doc

Introduction

It has been known for over 40 years that radon, a radioactive gas, is present in natural gas. Reports by R.H. Johnson² and C.V. Gogolak³ calculate the health effects due to burning natural gas in kitchen stoves and space heaters. In an US Environmental Protection Agency report, Raymond Johnson calculates the number of lung cancer deaths due to inhalation of radon in homes throughout the U.S. as 95 due to radon concentrations in the pipeline of 37 pCi/L.

Radon is an inert radioactive gas. This means it does not react chemically with other elements. Whatever radon is in the pipeline and is delivered to homes is released to the home environment from kitchen stoves and space heaters. The radon is not oxidized and is not made benign or non-radioactive in the burning process.

Since radon is an inert gas, when it is inhaled, the gas is mostly exhaled. Except radon will decay to other radioactive decay products, such as polonium, bismuth and lead. These are solid fine radioactive particles that can be inhaled and subsequently reside in the lung.

Most calculations assume this radon gas mixes uniformly within the living space and the concentrations of radon and its decay products are thereby diluted. Thus, once radon enters the home, the average concentrations depend on the home volume, and also on the number of air interchanges. Previous calculations by Johnson and Gogolak make specific assumptions about the average volume of a home and the number of air interchanges per hour. Their assumptions are not necessarily appropriate to apartments in major urban areas, such as New York City.

To estimate the health effects of radon in natural gas three factors must be addressed. One, the concentration of radon at the natural gas wellhead. Two, transport from the wellhead to the household. And, three, the dilution of incoming radon in the home.

The first step is to calculate the initial source term, the concentration of radon at the wellhead. The Marcellus shale formation is more radioactive than other sources of natural gas in the United States. Based on a simple model of a hydraulic fractured well, in the next section, we calculate the radon concentrations at the wellhead.

Radon at the wellhead is then transported through natural gas pipelines to distribution centers and to homes for use in cooking and heating. During the time of transport, radon decays. This radioactive gas has a half-life of 3.8 days.

Most of the natural gas currently consumed in New York State arrives from the Gulf Coast, a distance of 1800 miles. The closer to the point of use, the shorter the transport time. And the Marcellus shale is much closer, less than 400 miles to New York City. With a travel time of 10 mph in the pipeline, only about 25% of the initial radon from the Gulf Coast remains to enter homes. Since gas from the Marcellus shale travels a much shorter distance, a greater fraction remains. We estimate closer to 76% of the initial concentration of radon at Marcellus Shale wellheads will arrive at New York State residences.

Once radon enters the home through cooking, it is diluted within the home volume and also by air exchanges with the outside air. Radioactivity due to radon decay products is inhaled and resides in the lung, yielding a radiation dose to the lung. Using the latest dose conversion factors, based on ICRP-60, which convert the inhaled radioactivity to a radiation dose, we can calculate the radiation dose to an individual over a 30-year period. From the radiation dose to the population, we can determine the number of lung cancer deaths to New York State residents. As will be seen, the total number of lung cancers is significant, far more than estimated by Johnson in 1973.

None of this analysis appears in the Generic Environmental Impact Statement prepared by the New York Department of Environmental Conservation. In the entire 1400 page Environmental Impact Statement, one sentence appears. “Radon gas, which under most circumstances is the main human health concern from NORM, is produced by the decay of radium-226, which occurs in the uranium-238 decay chain.”⁴ (NORM refers to Naturally Occurring Radioactive Material.)

This one sentence is the full extent of the Department of Environmental Conservation’s analysis of the environmental impact of radon.