Climate change is fueling devastating storms like Hurricane Harvey that are mangling critical infrastructure and industrial facilities, causing dangerous pollutants to leak into the air. Physicist Tony Miller and his team at Entanglement Technologies have developed an air pollution detector that alerts people if the air is unsafe to breathe, and they were on the ground after Hurricane Harvey to help some of Houston’s hardest hit neighborhoods. This interview has been edited for length and clarity.
What brought you to Houston after Hurricane Harvey struck?
It was clear there were significant spills and damage in Houston caused by Hurricane Harvey, and a lot of exposure to toxic chemicals, but not necessarily resources to asses their impact and extent. We reached out to contacts at the Environmental Defense Fund (EDF) and asked if we could help, and they immediately responded ‘yes.’ Early the next morning, we started driving to Texas from California.
Air Alliance Houston and EDF funded our effort, and they had a set of priorities based on data reported to the City of Houston and the Texas Commission on Environmental Quality. They knew there were significantly elevated hydrocarbon levels, but couldn’t determine if that indicated highly toxic benzene or much less toxic toluene.
We can measure a range of chemicals with our AROMA analyzer, and focused on BTEX: benzene, toluene, ethylbenzene and xylenes. In Houston, we saw elevated concentrations of all of them. While each can be toxic, benzene is by far the worst.
During the week we were there, we detected six plumes. We saw the highest concentrations of benzene in the Manchester neighborhood, the very first site we measured, which abuts an active chemical refinery. A few blocks even mix residences and storage tanks.
The benzene came from a leaking tank less than 300 yards from the closest residence. Unfortunately, we don’t know what happened in the neighborhood in the days leading up to our measurements, and that’s a lesson: rapid response is critical.
It’s very difficult to collect good environmental data after an event like Harvey because every resource is strained. The government has to deal with an overwhelming number of problems at the same time, like damage to electrical lines, flooding, displaced people, risk of disease outbreaks, and mold growing in flooded homes. We quickly screened large areas to first prioritize for emergency response and then evaluate broader community exposure.
You monitored pollution all the way from California to Texas. What did you see en route?
A significant amount of the pollution we see in transit is caused by traffic we’re encountering — not just on the road, but also nearby. Gasoline can be up to 1 percent benzene, and when that doesn’t burn completely, you get benzene in vehicle exhaust.
Modern catalytic converters and emission control systems have done a good job helping reduce benzene, so some of the highest concentrations we’ve ever encountered were from historic vehicles. The worst we’ve ever seen was an original VW bug. Regulations have made a big impact on air quality.
How does your technology work?
Our optical sensor, AROMA, is built around a pair of mirrors — it’s exactly the same optical sensor that the [2017 Nobel prize-winning] LIGO observatory is using. Of course, ours is 10 centimeters long, and theirs is several kilometers long. It comes directly from quantum optics, and our device came out of work several of us at Entanglement were doing at Stanford and Caltech to make better sensors.
People have gotten very good at seeing interactions at an atomic scale, even a single atom with a single photon of light. We’ve taken that tool and scaled it up to look at chemicals in the environment. This set of tools has enabled us to get very high performance in a compact system. We use that sensitivity to help us distinguish different molecules.
What impact will chemical monitoring have in the future?
Refrigerants are some of the largest contributors to the greenhouse effect, and we’re looking into detecting and managing them in our next-generation instrument. Pound for pound, they’re much more impactful than even CO2.
Another chemical risk we’re starting to monitor closely is trichloroethylene (TCE), which can cause birth defects in the first six weeks of pregnancy. TCE leaks into the ground and groundwater, and it can rise into indoor air spaces. We’ve measured six sewer sources in the San Francisco Bay area near contaminated sites and found significantly elevated TCE concentrations in five of them.
And of course any time you have a major event where you can have real damage — like Harvey, or an earthquake, or a tornado — there’s a need to assess more than just what we can see. You want to know where there’s a fire, where there’s a damaged gas main and where there are chemical threats. Some climate models are predicting more events like Harvey. With more risk of damage to infrastructure, there’s more risk for those kinds of chemical exposures.
Our society has been built, in part, on our ability to manipulate the chemical world, and we’ve come to realize that a lot of the things we now use as tools have the potential to cause significant harm. Dealing with those chemicals — and being able to assess quickly whether or not they pose a risk — is where we see our technology being very valuable.
This interview was conducted by Josh Chamot, who writes for Nexus Media, a syndicated newswire covering climate, energy, policy, art and culture.