Safecast is a global sensor network for collecting and sharing radiation measurements to empower people with data about their environments.

Monitoring Fallout Decay

May 3, 2013 06:00 May 3, 2013 06:00 May 3, 2013 06:00
 

One of the great utilities of the Safecast project is the ability to collect and analyze environmental data on an unprecedented scale. As Safecast passes the two year mark with collecting radiation data in Japan it is now possible to begin to look back over the changes in radioactivity across different parts of the country and see where this may all be heading.

Radioactivity in Inzai, Japan

Radioactivity in Inzai, Japan. 18 months worth of data.

Safecast data from Iitate, Japan.

Radioactivity in Iitate, Japan. 24 months worth of data.

A scan of two cities

While events at the Fukushima Daiichi plant have led to the common association of all of Japan with radiation we have collected enough data to show that large swaths of the country remain near background (Approximately 30-40 counts per minute). One example of this is the city of Inzai, which lies between Tokyo and Narita International Airport, and is 193km southwest of the meltdown site.  As the first graph shows background levels slightly above what is considered typical, but there is no appreciable change from the middle of 2011 to the end of 2012 in terms of radioactivity.

The next city in our study, Iitate, is about 38km northwest of the Fukushima Daiichi reactor site, and shows both more significant exposure and a noticeable decay curve.  What is notable about the decay curve is that a decay half-life can be estimated to reasonable precision with the best-fit exponential decay function.  From this method we can estimate the decay half-life for surface radioactivity to be only one year from the two years starting in the middle of 2011.  This is notable as the decay half-life for the two dominant radioisotopes, Cs-134 and Cs-137, are two and thirty years respectively.  This implies that there are additional mechanisms at work in Iitate which are moving radioactive material away from the surface, such as erosion and the deposition of new topsoil, which are accelerating the decay of measurable radioactivity at the surface. Continue reading »

Safecast Air: How do we determine what to measure?

April 2, 2013 19:04 April 2, 2013 19:04 April 2, 2013 19:04
 

Global Map of Carbon Monoxide concentration.

Global Map of Carbon Monoxide concentration.
Courtesy of NASA


How do you address the question of what should be measured in the air to help determine its quality in a meaningful way? As Safecast has been expanding its efforts into monitoring air quality we’ve been sorting out what to measure based on the following criteria: public health, environmental interest, and durability of the sensors involved.

Public Health
The impact of atmospheric composition on various respiratory and cardiovascular conditions has been heavily studied for decades. Starting with the work of the Environmental Protection Agency and U.S. health standards we get a focus on gases such as Carbon Monoxide, which has the nasty habit of blocking the absorption of Oxygen into the bloodstream, as well as microscopic particulates, which will slowly damage lung tissue especially as the particulate size drop below a millionth of a meter (About 1/200th the width of a hair).

Personal air filters from different cities.

Personal air filters from different cities.
Courtesy of TOTOBOBO

Environmental Interest
Cities have an impact on their local atmosphere beyond the composition of any one target gas which has also been of interest to everyone from research scientists to people trying to reduce their air conditioning bill: the urban heat island effect. This effect is quite easy to demonstrate by comparing the surface temperature of an asphalt parking lot and comparing it to a grassy field on a sunny day. Cities, being mostly composed of dry and non-reflective surfaces, tend to absorb far more heat than the surrounding countryside. The result of which has been associated with an increase in summer fatalities, increased power consumption, and shifts in local rainfall patterns. The evolution in these patterns can be better understood even by just monitoring the local temperature and humidity across an urban area.

Downtown Atlanta in infrared.

Downtown Atlanta in infrared.
Courtesy Wikimedia.

Sensor Durability
While a number of target gases have been identified in our development work we do also want to deploy monitors which could run for years with little to no maintenance. For example, compact and robust sensors exist which can measure Ozone, Nitrogen Dioxide, Volatile Organic Compounds (e.g. Methane), and Carbon Monoxide. However, the sensors which could monitor Sulfur-containing gases such as Hydrogen Sulfide and Sulfur Dioxide, which are also associated with acid rain and respiratory ailments, tend to wear out over a scale of months.

Profile of a solid state Nitrogen Dioxide sensor.

Profile of a solid state Nitrogen Dioxide sensor.
Courtesy of SGX Sensortech.

These criteria, coupled with a need to run these sensors in a small volume on with a lower power consumption, leads to our current list of metrics for Safecast’s air monitoring efforts:
Temperature, humidity, Carbon Monoxide, Ozone, Volatile Organic Compounds, Nitrogen Dioxide, and particulate matter of diameter one micron and above.

New Safecasters joined in Chichibu

February 5, 2013 01:23 February 5, 2013 01:23 February 5, 2013 01:23
 

We are happy to announce that local citizens from Chichibu in Saitama Prefecture have joined the Safecast volunteer network. (Mr. Tateno, Mr. Sekine and Mr. Noguchi from the left)

Chichibu has beautiful countryside and is surrounded by mountain ranges. In winter the mountains are covered by snow. I found the scenery very attractive, and somewhat similar to Nagano.
It is believed that a substantial dose of cesium fallout affected this region after the Fukushima NPP accident on 3.11 in 2011. In order to understand the current situation, a local citizens’ group contacted Safecast. Chichibu is an area in which Safecast had not yet measured radiation levels.

The three people in the above photo are the founders of a local food radiation monitoring station called “The association to protect everyone’s health and life from radiation in Chichibu” (“Houshano kara minnano kenko to inochi wo mamoru chichibu no kai”). They are retired school teachers who run the monitoring station and provide services to check radiation contamination levels from food samples brought by local people. They use an Atomtex 1320A, a radiation detector made in Belarus which is designed for food, distributed in Japan by Advanced Fusion Technology, Co., Ltd.. At ¥1,600,000 it is an expensive unit. Local citizens pitched in to purchase the device, and any concerned resident can have food checked with the device by paying just ¥1,000 for a one-item test. A single-item test takes approximately 30 minutes, with adetection limit for cesium of 7 Bq/kg. They purchased the device in July 2012, and since then items they have tested which exceeded the allowable levels (100 Bq/kg) have been publicly reported through their newsletter.

So far, mushrooms, including shiitake, have shown high levels of contamination (the tendency of wild mushrooms to accumulate high levels of cesium became well known after Chernobyl). Here are some examples reported by the group:

Food type Region produced Month tested [Cs 134/137
detectd?]
Fresh mushroom Chichibu City Dec. 2012 209.5 Bq/kg
Wild mushroom
(Tamago-dake)		 Yokoze Town Oct. 2012 367 Bq/kg
Wild mushroom
(Ippon-shimeji)		 Chichibu City Oct. 2012 223 Bq/kg
Wild mushroom
(Aka-monitake)		 Ryokami Village Oct. 2012 219 Bq/kg

 

They also check the contamination level of soil collected from gardens and the points where water from gutters reaches the ground. The contamination levels of the latter are particularly high. For example, one of the tests found 119,700 Bq/kg at the highest. In the Chichibu area, people traditionally eat wild game, including wild deer and wild boar. Their tests have identified that wild animals have been contaminated, but although the samples they have tested have not been as high as those found in shiitake and other wild mushrooms, wild deer from the area with over 800 Bq/kg was recently reported in the press:

http://www.saitama-np.co.jp/news10/24/02.html


The above photo shows Chichibu’s “food monitoring station”

The core members of the group have been providing seminars, talks and workshops to share the information thy have collected. They are collaborating with neighboring regions to inform the public about radioactive substances. The group has been run mainly by retired school teachers, including a high school science teacher who retired once but has returned to teaching part-time. His knowledge about radiation has increased the credibility of the group in the eyes of locals. We look forward to including newly collected data from the Chichibu region to the main Safecast map soon.

Safecast volunteer Kiki
(Translated by Akiko)

Information, Misinformation, Disinformation (or, “These aren’t the droids you’re looking for.”) Part 1

December 29, 2012 18:07 December 29, 2012 18:07 December 29, 2012 18:07
 

Whose job is it to make this stuff easy to understand?

“YOU CAN’T ALWAYS FIND WHAT YOU’RE LOOKING FOR…..”
[Skip to Part 2] At Safecast we assumed from the start that our data should be accurate, easy to understand, informative, well-visualized, and easily accessible. In many respects this simply reflects “best practices” in information design, as well as a vision of social responsibility in which openness and transparency are paramount virtues. So when we make decisions about how to present our data, we adhere to principles of intuitiveness, depth, context, and dare we say it, beauty in design. We want to make it as easy as possible (AEAP) for people to find what they’re looking for, and to find out what it means. That’s why we’re continually miffed when official sources of information seem to be operating under an entirely different set of assumptions.

To be honest, the seriousness of government missteps and opacity during the early weeks of the disaster led us to accommodate ourselves to vastly lowered expectations in terms of the quality and accessibility of information we’d probably see from official sources. Even though it’s their job, and they are legally required to provide many kinds of information, many of us prepared ourselves for endless tooth-pulling and fact-checking about radiation information. So first, I’d like to give a sort of brief status update:
1) The government has made a lot of information available, more than we expected (because we expected nothing).
2) It still needs to be scrutinized, fact-checked, and independently confirmed.
3) There are still some areas where a lot of us have been pulling teeth for months and still haven’t been able to get the information we’re looking for.

So let’s just agree to live with #2 and #3 for the moment. It means constant effort on our part, but enough of us are constitutionally well-equipped for this kind of research-based tug-of-war that it’s not really that onerous at this point. We get good at it, we build trust, and people who were once opponents sometimes become allies, because frankly, they need our help.

But #1 is where we find ourselves really scratching our heads. There is all sorts of official information available, and a lot of it is proving reliable, but it’s rarely as easily accessible or informative as it should be. In fact, locating and using the data is usually as difficult as possible (ADAP) considering how easy it is now to find good information and web designers, and how inexpensive it has become. It should be easy to do a good job, if the people in charge really care about doing a good job. Continue reading »

Information, Misinformation, Disinformation (or, “These aren’t the droids you’re looking for.”) Part 2

December 29, 2012 18:06 December 29, 2012 18:06 December 29, 2012 18:06
 

A MEXT radiation monitoring post, aka “droid,” of a common type manufactured by NEC . This one is at the former Akasawa Elementary School in Aizu-Misato.

GOVERNMENT MONITORING POSTS

[Part 1 here] In recent months there has been a fair amount of controversy concerning the accuracy of the radiation monitoring posts the government has installed all over Fukushima prefecture, and in some neighboring prefectures as well. We wrote about it back in July, 2012:

TEPCO cheating on radiation levels by using “improved” monitoring posts

There are almost 700 of these monitoring posts (675 at latest count), which we refer to as “droids” because of how they look (see photo above). They are all powered by solar panels and use storage batteries.
[Update: 2700 monitoring posts have been installed as of Feb. 2013]
Through the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), the government spent a lot of money (we haven’t been able to find out precisely how much) to have them installed, and spent more money to have a web site made that displays the readings: MEXT realtime environmental radiation page

From this reasonably attractive-looking page, users are supposed to click on a prefecture, then on a region of the prefecture, and then choose from any one of a dozen or more municipalities. Then a scrolling list appears on the right hand side, and users can select a particular monitoring post to review (In the case of Koriyama City in Fukushima, there are 393 monitoring posts in the list). A zoomable, scrollable Google Fusion map appears, and the individual posts are marked by colored dots. Clicking a dot gives the current reading at that location, updated very 10 minutes it seems, and it is possible to download data for the entire month. So, thank you for doing that much, at least, MEXT.

This system sucks in many ways. While working with it in order to compare the MEXT readings with our own, we’ve found that it’s impossible to get an overview of more than a small part of Fukushima at any one time, that hunting down particular locations is incredibly time consuming and frustrating, that the cumulative time data does not go back far enough, and that the downloadable data comes with many restrictions and is difficult to pull down efficiently. Yes, MEXT made this system ADAP — As Difficult As Possible. Continue reading »

Visualizing a radiation hotspot

May 6, 2012 07:13 May 6, 2012 07:13 May 6, 2012 07:13
 

Explanation of the blotchiness of radiation levels along a road in Iitate mura area, Fukushima prefercture. Safecast’s Joe Moross shows how level vary dramatically over a few meters for both air and surface dose rates.

Information Disbursement

March 19, 2012 23:48 March 19, 2012 23:48 March 19, 2012 23:48
 

We publish our readings online, and now offline as well.

Safecast will be sharing radiation measurements with Minamisoma City

March 3, 2012 19:32 March 3, 2012 19:32 March 3, 2012 19:32
 
On February 21st we visited Minamisoma City’s Environmental Public Health Section under the Department of Civic Life.  As one of the municipalities near the nuclear plants, Minamisoma has been receiving a good amount of media coverage recently.  The city has expressed a strong interest in radiation measurements, and individual citizens are demanding that they want to know the radiation conditions as well.

At the meeting Minamisoma accepted the proposal for Safecast to make bGeigie measurements supplied by groups cooperating with Safecast activities available on the web and the city agreed to make use of such data.  It was also decided to provide a link to the Safecast.org website from Minamisoma City’s website.

Safecast volunteers will support groups taking measurements covering nearly all areas in Minamisoma City and Safecast will publicly release this measurement data as it is available.  These activities will start in March and are expected to be accomplished over a few weeks.

In the back row from left to right are Safecast’s Yuka, Rob Oudendijk and Mr Watanabe.  On the far right in the back row is Mr. Washiyama who is the contact person supporting this effort.

In front of the radiation monitoring display at the Minamisoma City Hall.  Mr. Watanabe (on the right) from Koriyama who arranged our meetings and Mr. Nishikawa (on the left, author of this post.)

Reported by Eiji Nishikawa
Translated by Steve Rife

Measuring Radiation in Snow

February 4, 2012 00:42 February 4, 2012 00:42 February 4, 2012 00:42
 

On January 22-23 it snowed heavily in Tokyo. To see if it affects radiation measurements I ran out with a few geiger counters to see if I could detect any change.

Snow in Tokyo

To measure the fresh snow I used 3 geiger counters and absorption filters:

  • Inspector Alert with 2″ pancake for measurement in CPM
  • Thermo B20 for measurement in Bq/cm2 (calibration setting for Cesium, so will be off in case of other nuclides)
  • Thermo PRD for gamma dose rate in uSv/hr

Snow activity measurement

Well, I did measure quite different levels compared to what the “normal” post-Fukushima levels are in my neighborhood (background typically around 30-40 CPM or 0.05-0.07 uSv/hr on the PRD).  I used a cloth to capture fresh snow fall as opposed to measuring snow that already had accumulated.

Continue reading »

World Karate Organization to do All Japan bGeigie Relay

January 14, 2012 11:51 January 14, 2012 11:51 January 14, 2012 11:51
 

On December 2nd, we handed one bGeigie to the Kenji Midori, the President of the World Karate Organization (WKO), or in Japanese “Shinkyokushinkai”. The WKO is well known in Japan and world wide for organizing the Karate World Championships. Actually the 10th World Cup was just held here in Tokyo.

from left to right: Sakurako Shima, Pieter Franken, WKO President Midori, and JAM

Continue reading »

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