When researchers piled into vans stocked full of testing equipment and drove around Galena Park and Manchester on the east side of Houston measuring toxic vapors in February 2015, it wasn't exactly a surprise that they picked up benzene in the air.

After all, Houston has long grappled with air pollution, and toxic substances like benzene — a chemical that the U.S. Department of Health and Human Services has determined causes cancer — have been showing up in neighborhoods near the refineries and other industrial complexes along the Houston Ship Channel for years.

So the researchers, led by Jay Olaguer at the Houston Advanced Research Center, knew what they were looking for going in. Benzene is found in crude oil and it's a tricky substance to deal with. It evaporates very quickly, but the stuff is heavier than air so it can sink and settle on low-lying areas. When it gets to water, it only dissolves a little bit, with most of the benzene simply floating on top.

And it can do real damage, even when you're exposed to it for only a small amount of time. When benzene enters the body, it makes the cells stop functioning correctly, so bone marrow might stop producing enough red blood cells, which leads to anemia, according to the Centers for Disease Control. The immune system might be damaged by changing the level of antibodies in the blood and triggering a shortage of white blood cells.

A short exposure to benzene can leave a person dizzy and confused with a racing heart along with tremors, headache and various other symptoms. Long-term exposure has been known to cause anemia, irregular periods in women and can lead to leukemia and other types of cancer in blood-forming organs, according to the CDC.

Most people would have bet that the benzene in the air would be tied directly back to the refineries. However, it didn't turn out to be that simple for the researchers at Houston Advanced Research Center, led by Jay Olaguer.

The researchers drove around in three vans packed with equipment to collect real-time data about the toxic vapors in the air, which was then analyzed by computers. The computers used weather patterns to trace the toxic vapors, and did indeed detect benzene at the expected places along the Houston Ship Channel. But the researchers also found large benzene releases tied to pipelines running through the area, Olaguer told KUHF this week.

The benzene spikes matched up with the pipeline systems and showed that the pipelines were sporadically belching benzene vapors. These unpredictable emissions were releasing benzene into the air at levels that were much higher than reported in the same areas in the 2011 National Emissions Inventory, the Environmental Protection Agency's air pollution inventory system that is built using data collected from state and local agencies.

Basically, while the data doesn't look that bad, relatively speaking, on the National Emissions Inventory, the HARC study shows that in real time, benzene is escaping into the air in Galena Park and Manchester at rates that are close to dangerous levels for short-term exposure. And those emissions are way over safety limits for long-term exposure, according to the study, which was published this month in the Journal of the Air and Waste Management Association.

Olaguer told KUHF that the HARC scientists need to do more research on the whole issue, but he says government regulators should wake up to the reality of the situation, that their methods of tracking air pollution need to be updated so that the samples are taken in real time and can catch it when toxic vapors of this magnitude are released.

