Archive for the ‘Mobile Phones’ Category

Science in the face of complexity

February 4, 2016
Jeff Dahn: Battery Expert at Dalhousie University

Jeff Dahn: Battery Expert at Dalhousie University

My mother-in-law bought me a great book for Christmas: Black Box Thinking by Matthew Syed: Thanks Kathleen ūüôā

The gist of the book is easy to state: our cultural attitude towards “failure”- essentially one of blame and shame – is counter productive.

Most of the book is spent discussing this theme in relation to the practice of medicine and the law, contrasting attitudes in these areas to those in modern aviation. The stories of unnecessary deaths and of lives wasted are horrific and shocking.


But when he moves on to engineering, the theme plays out more subtly. He discusses the cases of James Dyson, the Mercedes Formula 1 team, and David Brailsford from Sky Cycling. All of them have sought success in the face of complexity.

In the case of Dyson, his initial design of a ‘cyclone-based’ dust extractor wasn’t good enough, and the theory was too complex to guide improvements. So he started changing the design and seeing what happened. As recounted, he investigated¬†5,127 prototypes before he was satisfied with the results.¬†The¬†relevant point here is that his successful design¬†created 5,126 failures.

One of his many insights was to devise a simple measurement technique that detected tiny changes in the effectiveness of his dust extraction: he sucked up fine white dust and blew the exhaust over black velvet.

Jeff Dahn

This approach put me in mind of Jeff Dahn, a battery expert I met at Dalhousie University.

Batteries are really complicated and improving them is hard because there are so many design features that could be changed. What one wants is a way to test as many variants as quickly and as sensitively as possible in order to identify what works and what doesn’t.

However when it comes to battery lifetime Рthe rate at which the capacity of a battery falls over time Рit might seem inevitable that this would take years.

Not so. By charging and discharging batteries in a special manner and at elevated temperatures, it is possible to accelerate the degradation. Jeff then detects this with precision measurements of the ‘coulombic efficiency’ of the cell.

‘Coulombic efficiency’ sounds complicated but is simple. One first¬†measures the electric current as the cell is charged. If the electric current is constant during charging then the electric current multiplied by the charging time gives the total amount of electric charge stored in the cell. One then measures the same thing as the cell discharges.

For the lithium batteries used in electric cars and smart phones, the coulombic efficiency¬†is around 99.9%. But it is that¬†tiny of amount (less than 0.1%) of the electric charge which doesn’t come back that is progressively damaging the cell and limiting it’s life.

One of Jeff’s innovations is the application of precision measurement to this problem. By measuring electric currents with uncertainties of around one part in a million, Jeff can measure that¬†0.1% of non-returned charge with an uncertainty of around 0.1%. So he can distinguish between cells that 99.95% efficient and 99.96% efficient. That may not sound much, but the second one is 20% better!

By looking in detail at the Coulombic efficiency, Jeff can tell in a few weeks whether a new design of electrode will improve or degrade battery life.

The sensitivity of this test is akin to the ‘white dust on black velvet’ test used by Dyson: it doesn’t tell him¬†why something got better or worse – he has¬†to figure that out for himself. But it does tell him quickly¬†which things were bad ideas.

I couldn’t count the ammeters in Jeff’s lab – each one attached to a test cell – but he was measuring hundreds of cells simultaneously. Inevitably, most of these tests will make the cells perform worse and be categorised as ‘failures’.

But this system allows him to fail fast and fail often: and it is this capability that allows him to succeed at all. I found this application of precision measurement really inspiring.

Thanks Jeff.






A ‘Safe’ Dose?

January 30, 2012
Is there such a thing as a 'safe' exposure level to a hazard?

Is there such a thing as a 'safe' exposure level to a hazard?

In many areas of life we are exposed to hazards in the form of a substance or a process which may harm us. Mobile phones use microwaves ‚Äď physically similar to those used for microwave cooking ‚Äď but at a much lower power. We know that microwaves at high power are bad for us ‚Äď think of microwaved meal . ANd we know that mobile phones are pretty safe ‚Äď but is the exposure level from using a phone completely safe?

To the best of my knowledge, there is not a single case of a person having been harmed by using a phone (aside from as a result of the inattention they cause). But many people are still convinced that they are harmful. Indeed, for the people for whom this is a concern, the microwave radiation used by phones is intrinsically ‚Äėbad‚Äô. And they would consider any level of exposure ‚Äď no matter how low ‚Äď to be dangerous. And that led me to wonder if the concept of a ‚Äėsafe dose‚Äô really made sense?

One problem with microwaves, is that we can‚Äôt see them! And we never receive a large enough dose to sense them directly. This can lead us to either ignore the hazard (‚ÄúIts all nonsense!‚ÄĚ), or to become anxious that we are secretly being over-exposed (‚ÄúThey want to build a phone mast only 100 metres form my children‚Äôs school!‚ÄĚ). So let’s first learn some lessons from two hazards with which we are more familiar: sound and light.¬†Hazards? Surely exposure to sound and light is completely safe? Well, no. Exposure to loud sounds can cause deafness, and exposure to bright light – such as the Sun – can cause blindness. But it is not just excessively large exposures that cause problems.

Exposure to modestly loud noises does not cause immediate deafness, but prolonged exposure does reduce our hearing acuity, something we don’t usually notice for many decades. “I SAID WE DON’T NOTICE IT FOR DECADES!”. Similarly, exposure to normal sunlight causes a yellowing of the cornea which affects our vision in old age. So it is sensible to consider that exposures to sound and light should be limited so that in the course of our normal lives we are not unduly damaged.

But we also benefit from exposure to light and sound – indeed to withdraw exposure would be – quite literally – torture. As best we can tell, a whole lifetime of listening to sounds which are not-too-loud and exposing ourselves to light which is not-too-bright does us no harm and brings us wonderful benefits. So sound and light are not intrinsically ‚Äėbad for us‚Äô or ‚Äėgood for us‚Äô. What determines whether exposure to these ‚Äėhazards‚Äô is ‚Äėsafe‚Äô is judged quantitatively, not qualitatively. For a hazard of this kind, the concept of a ‚Äėsafe dose‚Äô makes sense, we get to enjoy the benefits and avoid the downsides.

What are the numbers for microwaves? The intensity of the microwaves inside a microwave oven is around 100,000 watts per square metre ‚Äď definitely bad for you. By comparison the intensity of visible light from the full summer Sun is roughly 1,000 watts per square metre. And a mobile phone? A few millimetres from the phone surface the maximum intensity is around 0.1 watts per square metre.

Sound and light are familiar to us, and so it is easy to understand the balance required in terms of reducing our exposure to avoid future harm.¬†¬†However microwaves are invisible and unfamiliar. So although the concept of determining a ‚Äėsafe dose‚Äô quantitatively is reasonable, it is easy to understand why people feel suspicious that we are being secretly harmed. Trusting your health to a regulatory authority is not quite as reassuring as being able to trust your own judgement. But I can’t think of any alternative.

Mobile Phone Safety: An Interesting Graph

January 11, 2012

Incidence of Cancers of the Central Nervous System: This graph is featured at the head of an article about increases in brain tumours arising from the use of mobile phones.

I came across the graph at the head of the page while looking at an article which asserted that there was evidence that mobile phones do indeed cause cancer. I was at first shocked РI had searched for data of this kind and found only data showing no detectable trend.  And then I was angered Рbecause the rise seen in this graph very obviously has nothing to do with mobile phones!

The offending page (The million dollar question: What is the risk of brain cancer from cell phone radiation?)is authored by one Dariusz Leszczynski and he comments on it thus:

The graph presented above, which has been generated by the Finnish Cancer Registry, shows a steady increase in brain and nervous system cancer cases among Finnish women and, to a lesser extent, among Finnish men.¬†Therefore, the “urban legend” that there has been no increase in brain cancer cases in recent years should be put to rest.

The implication in this context is clear: that this rise is in someway connected with mobile phone use. Now Dariusz does go on to say…

…we should remain cautious and not jump to the easy conclusion that cell phone radiation is responsible. Cell phone radiation may be the cause for the increase, but there have been other changes to the way we live and our environment, and so it might not be.

My problem with this is that contrary his assertion, Cell phone radiation could not possibly be the cause of the rise. ¬†Look at the dates! There is a clear rise in cancers of the brain and central nervous system starting in around 1960. Yes 1960. A quick browse of Wikipedia confirms that something called a ‘mobile phone’ did exist in the 1960’s, but it was rare and could not conceivably be the cause of the observed rise.

  • If a tiny number of phones in the 1960’s immediately caused an increase in cancer rates as shown, then the millions of phones we use now would cause the above graph to skyrocket.
  • Alternatively, if there was a latency period – as one would predict if mobile phone use did indeed cause cancer – then where is it? The data would be flat and then show rise after perhaps twenty years of use – that’s the typical latency between starting smoking and getting cancer.
  • Finally, notice that in the period since 1990 when mobile phone use has exploded, all that can be seen is exactly the same trend as seen in the 1960’s – but possibly flattening off.

So the the rise seen in the graph above cannot possibly be associated with mobile phone use.¬†So what did cause it? Well, I don’t know, but I would suggest it arises as the product of improved healthcare resulting improved diagnosis, coupled with improved¬†life expectancy – the graph below shows life expectancy for Finland using data from the wonderful ¬†Gap Minder. The data are nominally age compensated but as this page explains, the compensation is complicated.

I am not saying that mobile phones do not cause cancer: I don’t know whether they do or they don’t. I feel sure that time will tell. However, having looked for evidence that they do cause harm, I have never found any evidence of harm. And indeed the graph shown at the head of the page is actually evidence that the exponential increase in mobile phone use was not the cause of the observed rise.

LIfe Expectancy in Finland: Data from

My New iPhone

October 28, 2011
Me and my iPhone.

Me and my iPhone.

Re-assured by the news of a Danish study reporting no evidence for increased rates of brain tumours in mobile phone users, even over 17 years of use (full paper here), I finally bought an iPhone. The SAR rating of 1.17 watts per kilogram is not the lowest, but it seemed acceptable to me, and so I took the plunge.

I am still coming to terms with the way I have had to to re-organise my life in order to cope with the phone’s ways of doing things, but I have survived the weekend. I had thought the phone would fit in with my life, but having talked with other smart phone ‘victims’, I now realise that this was a naive hope.

Sadly, a building near my school which housed several phone masts has been dismantled and so mobile phone reception at home is rubbish. Oh how I wish they would build more phone masts.;-)

Incidentally, my first ‘app’ was ‘UK Energy‘ which plugs into the¬†ELEXON¬†database to extract real time data on the source of electricity generation. Having previously lost hours of my life on the Elexon site, I am really grateful to¬†Tom Weightman¬†for writing this¬†app.

A microwave dose of bananas

October 16, 2011
What is the analogy of the 'banana equivalent dose' for a mobile phone? Picture from

What is the analogy of the 'banana equivalent dose' for a mobile phone? Picture from

The BBC this week highlighted the relevance of the Banana Equivalent Dose Рthe dose of ionising radiation received as a result of eating a  banana. I commented on this just over a year ago (Would you eat a radioactive banana? ) where I pointed out that although the use of bananas to measure radioactive dose seems like a comic stunt, it is actually a serious metrological issue.

Measurement is the quantitative comparison of an unknown quantity with a standard unit. Ideally the standard unit should be familair to the people who will use the measurement. And ideally the the standard unit should be of a similar magnitude to the unknown quantity Рthis makes it easy for human beings to register the significance of the measurement. The banana equivalent dose is a useful unit because it is typical of the doses received by people outside the Fukushima fallout zone Рthey might be receiving the equivalent dose of 24 bananas per day (2.4 microsieverts per day compared with a standard expectedUK dose of 7 microsiverts per day). This is a lot of bananas from a dietary perspective, but quite appropriately, few people would fear radiological consequences.

This week I read¬†more stories of anxiety caused by the erection of mobile phone masts. It¬†made me wish there was an equivalent measure to the banana equivalent dose for non-ionising radiation. People’s anxiety is made clear in one quote from the Richmond and Twickenham Times:

Mrs Morgan said: ‚ÄúI did a study of radiation [before] and as far as I know nothing has been proved that this radiation coming from these things are not harmless to human beings. Until they prove they are harmless I think they shouldn‚Äôt be erected.‚ÄĚ

Sadly, the proof of safety that Mrs Morgan desires is impossible. There is currently no evidence of harm, but it may be that in 20 years, some evidence of harm from prolonged use may become apparent. However, if it does become apparent those who oppose the construction of mobile phone masts maybe responsible for an increase in the population dose.

The dose of non-ionising radiation from the phone masts is tiny compared with the dose from actually using a mobile phone. By opposing the construction of nearby mobile phone masts, when people use their phones they emit more microwave radiation than they would for a nearby mobile phone mast. If we had an equivalent of the banana equivalent dose, for non-ionising radiation we would be able to quantity this.

Perhaps it should be in terms of a one minute mobile phone calls to a mast 500 metres away. Then we could say:

  • If the mast is built near your home your extra dose will be the equivalent of X minutes of mobile phone calls to a mast 500 metres away, but the dose from every mobile phone call you make from home will be reduced by the equivalent of¬†¬†Y minutes of mobile phone calls to a mast 500 metres away
  • If the mast is not¬†built near your home, you will receive no extra dose of radiation ¬†from the mast, but the dose from every mobile phone call you make from home will be increase ¬†by the equivalent of¬†¬†Y minutes of mobile phone calls to a mast 500 metres away

If you have any ideas about how to express this non-ionising equivalent dose I would love to hear about them.

P.S. I asked my son whether he would eat a radioactive banana.No! ‘ he said, ‘I don’t like bananas!’. I then asked ¬†‘Would you eat radioactive chocolate?‘ to which he replied without a moment’s hesitation:¬†‘Of course I would!‘.

Mobile Phone Safety: Advice

October 8, 2011
Traherne Lodge Residents who blocked the installation of a mobile phone mast

Traherne Lodge Residents who blocked the installation of a mobile phone mast. Photo Courtesy of Richmond and Twickenham Times

Yesterday I noticed a story in this weeks Richmond and Twickenham Times about ‘people power’ stopping the installation of mobile phone masts on top of a nearby block of flats. I then walked to my computer and found an e-mail from some Protons for Breakfast graduates asking for advice on exactly same subject. In this case it was concern over proposed mobile phone masts in Kingston. I find this continuing concern really interesting.

We have been discussing this topic at Protons for Breakfast for 7 years, and overall people seem less concerned about this issue¬†now they than ever been. Indeed, it has been suggested several times that we drop the subject and talk about something different instead. Children’s only concern about phones is how to get a better one! But I feel that beneath the veneer of acceptance there is deep-seated suspicion of the technology and the mobile phone companies. And there seems to be a constant stream of stories about community objections to mobile phone masts. Since most people who comment on the matter say they feel less anxious about Mobile Phones after Protons for Breakfast,¬†I think the topic is worth retaining. And additionally we get to destroy things in a microwave oven :-).

So what did I say to the Protons for Breakfast graduates? Below is an edited copy of the letter

Dear Protons for Breakfast graduates,

  • I sympathise.
  • I don’t know whether mobile phones will eventually be shown to cause harm. Nobody knows that. But to the best of my knowledge there is not a single known case in which someone has been harmed as a result of using a mobile phone or because of proximity to a mobile phone mast. And there is no reason to suppose that any harm will arise in future. It is possible, but IMO unlikely. Time will tell.
  • The ICNIRP guidelines are estimated by finding the lowest level of known harm. The guideline exposure level for workers in then set at 10% of that level, and at 2% of that level for the public.
  • I live about 176 metres from a cluster of mobile phone masts. My children’s primary school playground was 76 metres from the same masts. I did the calculations and then did not lose a moments sleep on the subject.

Suggested Links:

Comments on articles on the BRAG web site

  • Response letter. Actually a pretty fair summary and the links in the letter are kosher. There really is no known harm.
  • EM Field sources in the home: I couldn’t understand that document.
  • WHO statement : Bland political statement.
  • The Influence of Being Physically Near to a Cell Phone Transmission Mast on the Incidence of Cancer: This paper is looks like a real scientific paper but is IMO nonsense. It is really extreme to suppose that 200 metres from a cell tower with an output of around 100 Watts (EIRO~1500W) that anyone is being harmed. The intensity reaching a person is ~37 milliwatts per square metre. Mobile phone handsets expose you to 10’s of watts per square metre. Sunlight is 1000 Watts per square metre. So if exposure at that level were dangerous – and there is strong evidence that it is not – then there would really be an epidemic of cancer. And there is not. And if cancer rates had risen by a factor 2 near phone masts there would be an epidemic of cancer – but there isn’t! Perhaps it was the presence of an old people’s home in one of the groups that caused the problem. See the Cancer research blog for believable data.
  • Electrosensitivity and the Church – Why you should not put mobile phone masts on churches. There is no evidence that electromagnetic hypersensitivity exists and there is evidence to show that it does not. I actually know one of the authors slightly (Denis Henshaw) and I have written to him to ask for his evidence that electro-hypersensitivity exists. If anything comes back I will let you know.
  • Cancer clusters at phone masts: I just don’t believe that. If it were true mobile phones would be dead as would a great many other people.
  • Call to ban mobiles and WiFi from schools: This is based on a Daily Express article. See my talk above for examples of nonsense media stories.
  • Approaching Epidemic: Brain Damage from Mobile Phone Radiation: This ‘Mercola’ peddles pernicious scare stories. There is no epidemic of brain cancer. I have written about him before and the link is above.
  • Bad science: Ben Goldacre is one of the few people who have the time to take apart some of the nonsense that is being peddled out there. He is a kind of saint.
  • Zac Goldsmith is a politician. By moving transmitters away from places where people are, he is advocating increasing their exposure to mobile phone radiation because when the base stations are farther away the handsets automatically increase their power to compensate. On any rational assessment it is better to have many more lower power base stations than to have a few stations that are very distant from the people that use them.

I hope this helps

Cancer Risk and Mobile Phones

June 26, 2011

Scroll down to the bottom of the graphic to find my story!

Cancer risk from Chemicals

Graphic designed by Professor John Adams. The orange square in top left represents the 30 chemicals we know that cause cancer. The beige area around it represents the 3000 chemicals we have fully tested. The grey area represents all the chemicals we know exists. Are you worried? Click for full size version.

The above graphic was part of a surprisingly lucid article on the BBC about our attitude towards activities where the risk of harm is simply unknown. This blog post is simply to show the above graphic and remind myself that BBC can still write good stuff when they put their minds to it.


June 2, 2011
Cancer Research Graph

The upper graph shows the effect of short-term use (less than 5 years), and the bottom one deals with long-term use (more than 5 years). Each dot shows the result from a single study. If it’s on the horizontal line, there is no effect. If it’s above or below the line, this suggests that phones might increase or reduce the risk of cancer respectively. Click for a larger graph.

A colleague at work flagged up a blog article on the Cancer Research UK web site and I just thought I would share the link with you.

The article is excellently written and I commend it to you. The article includes the graph above which shows the various studies attempting to detect the putative carcinogenic effect of mobile phones. The graph is discussed in a little more detail in the linked article.

If the points lie above the line and the uncertainty indicators – the bars above and below each point – also lie above the line then the researchers are claiming a statistically significant effect has been detected. You can see that the majority of studies fail to detect an effect but that one or two do. Pooling all the results to reduce the uncertainty they also fail to show an effect.

I have no comment but instead I leave you to make up your own mind on this issue.


May 31, 2011
A woman engaged in a WHO category 2B activity

A woman engaged in a WHO category 2B activity

Today I read that the World Health Organisation have classified use of a mobile phone in the same category as drinking coffee, eating pickled gherkins, or wandering through fern bracken: ‘possibly’ carcinogenic. While I don’t disagree technically with this categorisation, I think their decision is asinine and unhelpful.

As we cover in detail in the Protons for Breakfast course, there is a potential hazard associated with use of a mobile phones. Exposure to high intensity microwave radiation is definitely hazardous – ask any microwave meal – but exposure from use of a mobile phone is calculated to be low enough that the risk of damage is small or zero. The WHO categorisation essentially says that it cannot be ascertained whether the risk is zero (category 3) or small (category 1). Since there is no strong evidence of harm (‘probably ‘ carcinogenic = category 2A) they called it category 2B – ‘possibly carcinogenic’. And there I predict, it will stay for ever. The perfect safety of something, like the absence of blue swans, can never be established.

Despite the absence of an increase likely candidate cancers –¬†it is possible that use of ¬†mobile phones could conceivably cause cancer. The problem with the categorisation is that for most people it doesn’t help them to make significant decisions in their lives.¬†It would, for example, be more helpful for all concerned if the naming of category 2B was changed from

  • 2B = ‘possibly does cause cancer, but we don’t know for sure yet’


  • 2B = ‘probably doesn’t cause cancer, but we don’t know for sure yet’.

And then, coffee in hand, we could walk with our pickled gherkins through the bracken and call our friends and tell them that they didn’t need to worry so much.

The british press and the issue of mobile phone safety

April 27, 2011
A typical mobile phone user

A typical mobile phone user

Do mobile phones cause brain cancer? This is the question at the heart of concerns around mobile phone safety. This concern continues:

  • despite the fact that there is not a single known case of harm arising from the use of mobile phones* and,
  • despite the fact that incidence of the relevant cancers has not changed significantly¬†over the last two decades during which mobile phone use has risen exponentially and,
  • despite the fact that no one has provided a convincing model of how the phones could even in theory cause harm.

Now there are real issues around mobile phone safety, and we spend an evening discussing them in Protons for Breakfast. These issues should form topics that can addressed rationally by the press. It is possible, and as an example, please read this superb article in New York times (I think you may need to register to read the article, but it is worth it). It is written by Siddhartha Mukherjee, a cancer specialist, and introduces all the complexity of the subject in an intelligent and accessible way. It does not resort to platitudes, but simply reports the situation as it is. Reading it I felt reassured that intelligent journalism was actually possible.

Sadly, I ¬†have yet to read a single rational article about this the British press. I won’t bore you with the all the articles in my database. The stories are uniformly facile – even in apparently august journals such as The Telegraph – and designed explicitly to engender fear, uncertainty, and doubt. These are factors which newspapers believe encourage media consumption.

They stories are simply ‘hacks’ of whatever press release some journalist is required to create a story around. However, the most egregious nonsense moves beyond the pathetic to the truly spectacular, and the prize must be¬†awarded ¬†to The Independent on Sunday for its article¬†Mobile phone radiation wrecks your sleep. This was its front page¬†headline on Sunday 20th January 2008. The story begins routinely enough reporting results of an unrefereed conference article which claims that mobile phone radiation affected the sleep of a cohort of people studied. Scratching around for supporting evidence Geoffrey Lean (again) happens upon the result of a study which he claims supports his thesis:

It also complements other recent research. A massive study, following 1,656 Belgian teenagers for a year, found most of them used their phones after going to bed. It concluded that those who did this once a week were more than three times ‚Äď and those who used them more often more than five times ‚Äď as likely to be “very tired”.

Did you catch that? Yes. This is a major UK newspaper reporting on its front page that teenagers who use their mobile phones in bed are likely to report that they are “very tired”. Can you believe that an apparently reputable UK newspaper can publish such risible nonsense? I urge you to laugh – it helps keep back the tears.

* This excludes harm arising from inattention caused by distraction while using the phone which has caused many road deaths and at least one train crash.

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