Air Toxics Monitoring in New Jersey

NJDEP measures outdoor air concentrations of air toxics at four monitoring sites in New Jersey. They are located in Camden, Elizabeth, New Brunswick, and Chester. The Camden site has been measuring several toxic volatile organic compounds (VOCs) since 1989. The Elizabeth site began measuring VOCs in 2000, and the New Brunswick and Chester sites became operational in July 2001.  Also in July 2001, analysis for toxic metals began at all four sites.  Air toxics monitoring data summaries can be found in the annual NJDEP Air Quality Report.  Some results are discussed below.

COMPARISON OF THE 1999 NATA RESULTS TO THE MONITORED CONCENTRATION OF AIR TOXICS IN NEW JERSEY

Twenty-three of the compounds measured at the Camden monitoring site in 1999 had enough data to compare to the 1999 NATA modeled concentrations.  The Camden monitoring site is located at Copewood and Davis Streets, in census tract 6015.  The monitoring data was compared with the modeled concentrations predicted by 1999 NATA for that census tract.  The comparisons are shown in the graph and table below.  It appears from this analysis that the agreement between the predicted and monitored concentrations is remarkably good for most of the chemicals.  Modeling predictions are dependent on many variables, any of which can  vary from the actual conditions, and many of which can not be accounted for.  The results produced by the modeling depend on emission estimates for stationary, area, and mobile sources, meteorological conditions, and how well the dispersion model represents what happens in reality. 

Monitored Concentrations of Air Toxics at Camden in 1999
Compared to 1999 NATA Predicted Concentrations

Monitored Concentrations of Air Toxics at Camden in 1999
Compared to 1999 NATA Predicted Concentrations

TRENDS IN MONITORED AIR TOXICS CONCENTRATIONS

The graphs below show the ambient air concentrations for five air toxics that have been monitored in New Jersey over the years.  Benzene, 1,3-butadiene, and formaldehyde are pollutants of concern in New Jersey, meaning that their air concentrations exceed their health benchmarks.  Monitored levels of toluene and xylene have consistently been below their health benchmarks.

Benzene

Benzene is emitted from many different types of sources, but primarily from mobile sources.  It is a major component of gasoline.  It is widely used as a solvent, and as a starting material in the production of numerous other chemicals.  It ranks in the top 20 in production volume for chemicals produced in the U.S., although its use in consumer products (glues, paints, furniture wax, detergents) has been decreasing significantly.  It is a known human carcinogen.

1,3-Butadiene

1,3-butadiene primarily comes from on-road mobile sources (cars, trucks), so it is not surprising to see higher levels at the Elizabeth monitoring site, which is located next to the New Jersey Turnpike.  Other it also used in the production of rubber and plastics.  Although the overall trend in the air concentration from 1994 has been downward, levels measured at every site except Chester (in rural Morris County) still tend to be above the health benchmark.  1,3-butadiene is classified as probably causing cancer in humans.

Formaldehyde

Formaldehyde air concentrations are affected by direct emissions, and by formation from the interaction of other pollutants.  Formaldehyde is emitted during the production and use of household goods (such as cosmetics, cleaning products, and manufactured wood products) and industrial chemicals, and sources of combustion (such as cigarette smoke, gas cookers, fireplaces, and of course, automobile exhaust).   The graph shows that formaldehyde concentrations haven’t changed much in the recent past, and aren’t even very different in urban and rural areas.  Levels are above the health benchmark.  Formaldehyde is classified as a probable human carcinogen. There is no data point for 2003 because of a monitoring instrument malfunction.

Toluene and Xylene

Toluene and xylene, presented in the graphs below, are components of gasoline, and are emitted mostly from mobile sources.  They are also used in large quantities as solvents and in the production of other chemicals.  These chemicals are used in the manufacture of paints, coatings, insecticides, pharmaceuticals, adhesives, and many other products.  Fortunately, NJDEP’s air monitors show them to be at levels below their health benchmarks.  They are not known to cause cancer.

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