We live in a radioactive world. That simple fact about our planet kept coming to me in the weeks and months after March 11, 2011, when the Fukushima Dai-ichi Nuclear Power plant overheated, exploded and began releasing radioactivity into the ocean and atmosphere. It was a fact that I also learned after Chernobyl in 1986, when I was a graduate student in chemical oceanography studying plutonium in the ocean produced during nuclear weapons testing.

In the days and years after Fukushima, I would find myself responding to audiences up and down the West Coast who expressed concern about reports of a radioactive “blob” making its way across the Pacific or dead birds found on a beach or decomposing starfish. I kept hearing the same questions from worried parents, fisherman and surfers: Is it safe? Should I stay out of the water? Can I eat seafood? Is the Pacific dying?

I am a scientist, so my first response after the accident was to head to Japan, collect samples and assess the situation. Near the reactors, where we were not allowed to sample, levels of radioactivity in the ocean spiked to more than 10 million times the pre-accident background in early April. By the time we arrived in June, levels had thankfully had fallen thousands of times, but it was still easy to detect this new source of radioactivity as it mixed into the ocean and began moving inexorably east.

To my surprise, as radioactivity levels near Japan decreased, public concern in the United States increased. Maps pinpointing the spread and dilution of radioactive cesium-134 and -137—the principal markers of radioactivity from Fukushima—did little to allay public concerns. But because no federal agency claims oversight for radioactivity in ocean water, there was no place I could apply for funding to respond to these concerns in a comprehensive way. And since there was also no way I could take everyone in California on a research cruise to see what I was seeing, I decided to get people to see for themselves how much radiation there was.

The result was Our Radioactive Ocean (ORO), a crowd-funded campaign to measure the levels of radioactive cesium along the West Coast of North America and around Hawaii. Our goal was to empower individuals and groups to collect water at their favorite beach with our simple kit, then send the sample to my lab for analysis. In the process, they would take ownership of the information we returned to them and hopefully become ambassadors for the scientific process and the knowledge that we assembled, one sample at a time.

What started out as a blank map of the eastern North Pacific, is now dotted with well over 300 sample locations. More importantly, we have photos of families, surfing groups, and classrooms, all wading into the ocean to collect a sample—their sample. The results we have assembled show that radioactivity levels in the ocean off the West Coast are lower today than they were in the 1960s when similar radioactive contaminants were first released as fallout from nuclear weapons testing.

While the risks remain small, there are many reasons to keep monitoring the situation in this way until levels decrease to pre-2011 values.

The success of our efforts can be measured not only by the number of samples we’ve received but in the number of opportunities we’ve had to teach people about radiation in the ocean. As an academic who reaches just a few hundred fellow scientists at a time via peer-reviewed publications, I was astounded by the fact that we recently passed the milestone of 1 million views on the ORO web site and that we continue to receive inquiries about collecting samples.

Beyond the impacts of Fukushima, engaging the public to learn about the basics of radioactivity and the risks involved is important as we weigh the impacts of nuclear power against other sources of energy. But this is not enough.

With over 400 nuclear power plants around the world, many adjacent to or draining into the ocean, it is imperative that we have a cadre of citizens and scientists working side-by-side to understand the impact of radioactivity on the oceans. Engaging citizen scientists doesn’t get us all the way there, but it is a step in the right direction.