By now, we should all be aware of the risks associated with carbon monoxide poisoning. That is the gas which can make you sick, or even worse, which results from incomplete combustion. Faulty furnaces and leaky auto exhaust systems are a common source. You might even recall that a famous tennis star was tragically killed as a result of carbon monoxide poisoning in an accident relating to an improperly vented pool heater.

That is the carbon monoxide dilemma. It is dangerous, but we all know that if you purchase a carbon monoxide detector, the problem can be controlled. Now that we have finally come to terms with this issue, here comes another gas related red flag: problems associated with nitrogen oxides.

When fossil fuels such as oil, coal, and natural gas are burned, nitrogen oxides are also released into the air (as is also carbon monoxide). These resulting gases are dangerous for two reasons. First, they react in the air to create ozone, which in turn causes smog. Smog is especially a problem for people with respiratory problems. Second, it is reported that at high levels, this gas itself can cause lung damage.

The two primary sources of nitrogen oxides are car emissions and emissions from electric power plants. Recall how in the past I have mentioned that one of the biggest sources of air pollution is coal-burning electric power plants. This is the kind of thing to which I was referring.

For decades, scientists have focussed on the carbon monoxide issue. Now, it appears that nitrogen oxides are also on their collective radar screens. For example, last year the Agency charged with protecting San Francisco's air quality was sued in federal court by several oil refining companies. They claimed that the Agency's attempts to curb nitrogen oxide releases from the refineries are not supported by real science. The refiners asserted that they are not contributing to the ozone threat and that, in some manner, they may actually be reducing ozone through their processing operations. A hard to believe position, but who knows?

Nitrogen Oxide concerns are not limited to outside your home. We all know that too much time spent in the kitchen can be unhealthy; but most of us thought that was due to the potential for overeating. Another reason to stay out of your kitchen relates to the risk of increased nitrogen oxide exposure.

An Australian governmental organization, the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO), has conducted indoor air sampling studies to determine which areas of the home are safe and which are not. CSIRO found that levels of nitrogen oxides are often higher in the kitchen than anywhere else inside the home. A CSIRO researcher spent 20 weeks wearing a personal air pollution sampler and reached this conclusion.

Australians are reported to spend an amazing 95% of their time indoors. Understandably, therefore, indoor air quality issues tend to be even of greater concern down under than here in the United States. Of course, my own children spend about 100% of their time indoors, watching television!

Specifically, indoor nitrogen dioxide levels were generally found to be low, averaging nine parts per billion (ppb), contrasted with 16 ppb readings outdoors. This means that most areas of the home contain lower amounts of this gas than are found at outdoor naturally occurring levels. A kitchen, however, with a gas oven, produced levels of 32 ppb, twice the outdoor concentrations. And if you have a gas heating furnace, presumably this increases possible exposure.

It seems that the Australian study was too limited in scope to draw any hard conclusions. And, the study does not conclude that this increased exposure is, itself, harmful. With many pollutants, its is not one source that causes problems, but rather the combined effect of all exposures.

While outdoor air quality has been monitored for years, we have only recently begun to consider the issue of indoor air quality. In the end, maybe we will learn that it does not matter whether harmful pollutants originate indoors or outdoors. It is the cumulative effect of exposure that matters: how much exposure has there been from all combined sources, and over what period of time?

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Published: May 6, 1999

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Stuart Lieberman, Esq. writes about environmental issues. He was a New Jersey Deputy Attorney General assigned to the State Department of Environmental Protection from 1986 to 1990. Currently he is a shareholder in the environmental law firm of Lieberman & Blecher, P.C., located in Princeton, New Jersey. Stuart can be reached at slieberman@liebermanblecher.com.