Live from Austin!

A recent BBC Panorama documentary has suggested that wifi Internet might be a major health hazard. Scary quotes about chromosome damage and radiation exposure have appeared all over the Internet.

Unfortunately, the documentary’s conclusions are junk science.

Let’s start off by noting the inverse square law, a piece of basic physics which applies to electromagnetic radiation exposure. Basically, the strength of a signal varies in proportion to the distance squared.

The people who put together the documentary measured the wi-fi signal at a distance of 1m, and the cell phone tower signal at a distance of 100m. From their measurements, they concluded that the wifi signal was “three times the highest level of the mast”.

Well, no, it wasn’t. Because the cellphone signal was measured 100x further away, it was attenuated by a factor of 100×100 = 10,000×. So an accurate quote would be that the wi-fi signal was “three times the level of the cell phone mast divided by 10,000″. Not as exciting, though, is it?

You might argue that it’s reasonable to measure at different distances because people don’t tend to sit close to cell phone masts, but they do tend to sit close to wi-fi equipment. However, think for a moment about how a cell phone works. Yes, the mast transmits a signal to your phone, which is 10,000× weaker by the time it gets to you. However, you don’t just listen to your phone; hence, it must also transmit your voice back to the network. And the same physics works the other way: the signal your phone transmits is 10,000× weaker by the time it gets back to the mast.

So as you might guess, the radiation your phone emits is much, much more powerful than the radiation that reaches you from any nearby mast. That’s the radiation levels the BBC program should have been measuring and comparing with wi-fi.

While raw power is measured in watts, the relevant measurement for assessing radiation danger levels is the Specific Absorption Rate or SAR, which is measured in watts per kilogram. An adult’s body has much more bulk to dissipate the electromagnetic field, hence it’s less susceptible than (say) a lab rat’s body.

The US limit on radiation from consumer mobile phones is 1.6W/kg. (That’s lower than the European limit, so we’ll take that as our guideline.) The limit for devices like wifi is a mere 0.08W/kg. (Figures are in FCC OET Bulletin 56.)

Those are the maximums. The actual SAR ratings of common mobile phones are well documented. A value of 0.9 is fairly normal, with few phones below 0.5. So already, it’s clear that the average mobile phone actually exposing you to 0.9W/kg is likely far more dangerous than the 0.08 W/kg theoretical maximum allowed for devices like wi-fi.

Let’s look at some actual figures for wi-fi output compared to phones. I haven’t managed to find SAR ratings for wi-fi (if you have any, let me know), so we’ll have to compare power output in both cases. Peak power output from a phone is around 2W, with the average being around 250mW, according to a handy page from the Australian Radiation Protection and Nuclear Safety Agency.

Coincidentally, 250mW is the absolute maximum power output you can get from my wi-fi router (a Linksys WRT54GS). But to get that, you have to hack the firmware. The default power output for the router is around 20mW, 100× less than the phone. Now add in the fact that mobile phones are held against your head, whereas your wifi antenna is likely at least 30cm away from you at all times, and invoke the inverse square law again. The end result is that the electromagnetic radiation you get from wifi is a tiny fraction of that which you get from mobile phones.

As a UK Health Protection Agency scientist puts it in The Times, “a year sitting in a classroom near a wireless network is roughly equivalent to 20 minutes on a mobile.”

Aha, you say—what if you don’t use the mobile phone much? I’m afraid you still get irradiated. As you travel around, the signal from the nearest cell will get weaker. The phone checks signal strength every 7 seconds. If it drops off too far, the phone sends out an “I’m here!” transmission in order to locate another cell.

Given that each cell covers a square km or two, or as little as a few blocks in cities, taking a quick drive across town can involve your phone transmitting dozens of times. So wi-fi is a pretty negligible concern compared to carrying a mobile phone, let alone using one.

Wi-fi and phones aren’t the only sources of electromagnetic radiation, though. Wi-fi operates at 2.4GHz, which just happens to be the same frequency as your microwave oven. In fact, you may have noticed that your wi-fi signal strength is lower if you’re cooking something in the microwave, especially if your laptop is in the kitchen.

You might wonder why wi-fi operates at the same frequency as microwave ovens. Well, microwave ovens operate at 2.4GHz because that’s the frequency that’s best for heating up water molecules. For the same reason, it’s a bad frequency for long distance telecommunications through damp air, so it hadn’t been grabbed for any major commercial purpose. Hence, it was declared as free unlicensed spectrum for local low-power radio. This lack of regulatory hurdles led to innovation such as cordless phones, wireless video surveillance systems, and (eventually) wi-fi.

This also means that the effect of microwave exposure at wi-fi frequencies is simply heat. It’s not like nuclear radiation, it doesn’t mutate your genetic material; it simply warms up your water molecules a bit. From a scientific perspective, people are having a hard time coming up with theories to explain why localized warming of the body might cause damage. (In fact, it’s reported anecdotally that sailors on night watch on deck during WW II would stand in front of the radar in order to keep warm. They got hundreds of times the electromagnetic radiation warming you could ever get from a phone, yet they apparently didn’t suffer major damage.)

But let’s head back to the kitchen. Microwave ovens are allowed to leak up to 5mW/cm² at 5cm distance. A leaky oven may expose you to 0.256W/kg, at the same 5cm distance, according to measurements of leaky microwave ovens from the Australian Radiation Protection Agency. So at typical watching-lunch-rotate distance, it’s about the same level of danger as the radiation from your wifi router. So if you’re worried about wi-fi, you should be worried about your microwave oven too.

But there’s a much larger source of microwave radiation in your life. It’s called the sun. Summer sunlight at ground level can be up to 100mW/cm² of electromagnetic radiation. So standing outside on a sunny day irradiates you with 20× the radiation of a leaky microwave or wifi router, and a good chunk of it is microwave frequency.

So if you’re worried about electromagnetic radiation, perhaps the rational thing to do is what us computer scientists do—stay inside and browse the Internet via wi-fi, but never emerge blinking into the daylight…

Meanwhile, there are a growing number of people who believe that they are sensitive to low levels of microwave radiation like that found in wi-fi and sunlight. They call the phenomenon “electrosensitivity”. They claim that wi-fi and mobile phones give them headaches, make them nauseous, and so on, after just a few minutes. So, what’s the evidence?

Well, so far there have been at least 7 separate scientific trials in which allegedly electrosensitive people were asked to tell researches whether a mobile phone signal was present. In proper double-blind trials, “electrosensitive” people were unable to detect a mobile phone signal even after 50 minutes of continuous exposure. (Update: Here’s a very recent one.)

And even if they could have detected the signal—which they couldn’t—that wouldn’t have proved that the signal was responsible for their reported symptoms.

So if you believe wi-fi or mobile phones are making you ill, please do see a doctor—specifically, a psychiatrist. You may have a psychosomatic illness, you may be schizophrenic and believe you are picking up radio waves with your teeth, but you are not being made sick by people’s wireless Internet. If you truly believe you can tell when a mobile phone or wi-fi system is transmitting, sign up for a research study and prove it. You’ll be the first.

The sad thing is, though, that there are crackpots in even the highest levels of government. So expect to see more scare stories about wi-fi in the next few years.

I’m old enough to remember that back in the 80s, the scare story was about overhead power lines. They were making us nauseous, giving us cancer and leukemia, causing headaches. Funny how that risk seemed to vanish.

Microwave popcorn uses an artificial butter flavoring called diacetyl.

Numerous studies have now linked diacetyl fume inhalation to a rare condition called bronchiolitis obliterans, in which the bronchioles of the lungs get blocked by masses of fibrous tissue.

The problem has been known about since 1999, but so far federal agencies haven’t done anything. There’s now a bill in California proposing to ban diacetyl by 2010.

The Delve Special episode “Food for Thought” just seems more and more relevant as the years go by.  Random quote: “Everyone has to die of something, so it might as well be something delicious.”

Done so far:

• Curtains, rods, holdbacks fitted in living room.
• Books unpacked onto bookshelves in office.
• Partial repair to drywall around coax socket in living room, to be completed during the week.
• Two sets of vertical blinds fitted in office.

Today we had a guy spec out a home security system. We’re in what they call a ‘transitional’ neighborhood–while it’s all families immediately around us, a block away is one of Austin’s housing projects, and the kids get the bus from the stop at the end of the street. While I don’t want to be a yuppie prick, I’m conscious of the fact that I’m setting up an office full of tempting computer equipment. So, sensors on both of those windows… But I promise not to drive the BMW to Starbucks.

We’ve got quite a lot of stuff to get rid of, annoyingly enough. A microwave (the kitchen came with one built in above the oven), a cafe-style table with two stools, some folding chairs, a rug, that sort of thing. I’m also going to try and simplify a bit, get rid of the rather excessive number of devices for playing shiny silver discs, and get a single universal player.

The train is audible in the evenings; you don’t hear the train itself, but you can hear the horn. Then again, you can hear train horns in most parts of central Austin, and I’d rather have occasional trains in the evening than a constant rumble of traffic. The neighborhood dogs are louder.

Another noise nuisance is the peacocks. I kid you not, a restaurant a block or two away keeps peacocks, and apparently allows them to wander the street. If you’ve never heard a peacock crowing in the morning, it sounds a bit like a distressed kitten with a PA system. Once I dig out the MiniDisc recorder I may make some recordings.

We tried our new oven tonight. I had no idea that food cooked in an expensive oven might actually taste better than food cooked in an old cheap oven–but it does. It was amazing.

The toaster in the hotel room gave off an interesting flash and a zap noise the other day, and now it only toasts on one side of each slot; the middle element is burned out. It wasn’t a very good toaster to start with, and having to take the bread out and turn it around wait to toast the other side was reminding me of the days before autoreverse cassette decks. The hotel room has no oven either, just a third-rate microwave, which has been cramping our culinary style a lot and causing excessive amounts of eating out.

We had a toaster oven in Cambridge. It had previously been Laura’s, and had been exchanged for food before she moved away. It hadn’t been very good at making toast either, but we hadn’t been planning a long term relationship with it. A combination of neglect and difficulty of cleaning had meant that it had gradually accumulated grime inside until it began to give off interesting smells and occasional smoke during use. So, it had been given to some guys who had turned up with a truck to scavenge from our kerbside leavings. (I’d posted an open invitation to a couple of mailing lists.)

The toaster before that had always been hopelessly unpredictable, requiring constant supervision when making toast. Then one day it just stopped working altogether. It didn’t seem to have any kind of fuse, so it became toaster roadkill.

Still, that was a less spectacular failure than our first toaster oven, which I had set fire to in Malden by trying to cook tacos. Anyhow, point being, my experience with toaster ovens has been pretty negative. But it was clearly time to buy another one, so this time I was determined to get one that wasn’t going to break, catch fire, prove impossible to clean, or only toast one side of the bread.

You wouldn’t think it was that hard to design a toaster oven. I mean, basically it’s just a box with two electric heating elements in, a door on the front, and a sliding shelf. However, looking at this one I can see that it has a number of features that our previous crappy toaster ovens have lacked.

For starters, it has proper thick heating elements, rather than bits of wire wound around circuit board that burn out after a few months. It also takes the revolutionary approach of having identical heating elements top and bottom, so that the stuff you cook can be heated evenly on both sides.

Also unlike previous units, this one is designed to be cleanable—they’ve actually bothered to teflon-coat the inside. The final piece of toast-making rocket science is that the rack for the toast can be placed in the middle, equidistant from the two elements, so that both sides of the bread end up equally toasted.

Switching gears, today was the East Austin Studio Tour day. Dozens of local artists got together to open their studios to the public. Many of them laid on coffee, cookies, snacks, and a few even had alcoholic beverages available. We got a Christmas gift for my aunt and uncle, and sara got some amazing handmade arm warmer things.

I created a Sim Ryan last night, and built him a small one-bedroom apartment with cheap furniture, a computer and a TV. As soon as the neighbors came around to say hi, he latched onto Bella Goth and started chatting her up like crazy, much to her husband Mortimer’s annoyance. After Mortimer stomped off in a huff, it was all going well for SimRyan… until he tried to cook a romantic meal for two, and set fire to the kitchen. By the time he’d stopped panicing for long enough to call the fire department, practically everything was destroyed.

Once I’d persuaded him to clean up (no easy task) I replaced the oven with a microwave. He seems to be able to deal with that better. I don’t know what I was thinking giving him a gas oven in the first place…

Career-wise, he started as a mail-room boy, and somehow through demonstrating the ability to fix the photocopier he’s wangled a job as an executive assistant after just over a week.

It’s possible to measure the speed of light using only a bag of marshmallows and a microwave oven.

I knew it was time to go home Friday afternoon, when I found myself standing in front of the microwave waiting for my printout to appear.

Felt better this morning. Went into work. Felt tired by noon, had a splitting headache after lunch. Came home, went to bed. Just woke up, had microwave pizza.

Going to work from home tomorrow. Hope I can be well by the weekend.

Never let it be said that I’m not doing my bit to try and prevent a recession. This weekend it was time for a new mobile phone.

My old phone is a Bosch World 718. It’s a lovely phone; reliable, good sound, excellent build quality, adequate battery life, and works pretty much anywhere in Europe or the USA because it’s dual-band GSM. The only problem is, it’s 1996 technology, which means it’s the size and weight of a brick compared to today’s phones. Which in turn meant that I was less likely to carry it everywhere.

So, it was time for an update. I looked at the Ericsson T28w, another dual-band phone, but I must admit that I was put off by the fact that it has the highest radiation levels of any phone on the market.

As a skeptical scientific type, I know that there is zero evidence that cell phones cause cancer. In fact, there’s a scientist at MIT who regularly exposes herself to insane quantities of microwave radiation. During WW2, sailors would stand in front of the emitters on cold nights to keep warm. If EM radiation caused cancer, we’d have seen some pretty horrific cases by now.

Nevertheless…

I also wasn’t entirely convinced by the T28 flip mechanism. Especially when I saw that the one in the store had broken off. In the end I settled on a Nokia 8290—about the same size, but a quarter of the radiation, and it has a bunch of features which are nice to have, albeit not essential.

First off, the 8290 has no external antenna. This helps when keeping it in a pocket. It’s actually small enough to just stuff into the pocket of my jeans, which is amazing.

Secondly, the 8290 has IR support. You can beam phone numbers, SMS messages and other data between a PalmOS handheld and the phone. If I wanted to pay more, I could even get wireless web and e-mail access.

And finally, the 8290 has replaceable faceplates. That seems frivolous, but it means that when the front of the phone gets scratched up from being in your jeans pocket all the time, you can just get a new plastic faceplate.

I also like the fact that I can now set access control for incoming calls, and have predefined settings for different places. So I can put the phone in a pre-defined “meeting” mode, where only certain people are allowed to disturb me, and the phone vibrates without ringing. I also got a handsfree headset for free, but I haven’t tried it yet…

I’m still keeping the Bosch for when I travel to the EU. But for the 99% of the time that I’m in the USA, the Nokia’s a much better solution.

I bought a microwave egg cooker. (Requires microwave oven, not included.)

I revel in the technology which allows me to produce a boiled egg in one minute.

For breakfast, I had two boiled eggs. Had I had only one, I would have saved almost one minute of my valuable time. (Ignoring the time it takes to wash the microwave egg cooker.)