air polluntants

Have you heard of Poly-Cyclic Aromatic Hydrocarbons (PAH) ?


What started with a poster

I encountered some students from American Canyon High School in Benicia who created a poster about the hazards of PAHs while exhibiting at The Youth for the Environment & Sustainability Conference (YES) in San Francisco.

When discussing the usual contaminants in the air we breathe, words such as smog, haze, soot, sulfur dioxide, nitrous oxide, and particulate matter are used.

One of the terms you do not expect to hear is polycyclic aromatic hydrocarbon (PAH). For those of you who might not be familiar with these compounds, PAHs are chemicals that occur naturally in coal, crude oil, and gasoline. They also are produced when coal, oil, gas, wood, garbage, and tobacco are burned.

Where I have encountered  poly-cyclic aromatic hydrocarbons

PAHs are composed of two or more fused aromatic or benzene rings. Two aromatic rings are fused when a pair of carbon atoms is shared. The resulting structure is a molecule with all carbon and hydrogen atoms lying in a single plane. PAHs consist of thousands of structures originating from at least three sources, and they always occur in the environment as complex mixtures.

I was exposed to these compounds for the first time during a project I participated in as a project engineer with a soil remediation project I worked on. The presence of these compounds was detected in the soil, which needed to be remediated before the land could be turned over for development.  The area in question used to house a medical device production facility that was no longer operational.

How PAHs wind up in our air

Breathing air contaminated with motor vehicle exhaust, cigarette smoke, wood smoke, or fumes from asphalt roads is a common way exposure occurs. People take in PAHs when they eat grilled or charred meats, or foods on which PAH particles have settled from the air. In most cases, these chemicals are formed from incomplete combustion of organic materials such as the processing of coal or crude oil, combustion of natural gas, cooking, and tobacco smoking.

Final thoughts

I was glad I came across the poster, because we all need to be reminded that these carcinogenic compounds are present in many household items. These do not receive as much press attention as common air pollutants such as smog or haze. However, just because these compounds are not in the nightly news does not mean people should not worry about their existence.