Ask the Wi-Fi Guru About Wi-Fi Radiation Worries

By Aaron Weiss

September 09, 2010

Our monthly Q&A series offers advice to those seeking help with home or small business WLANs. This month our guru offers some insight into concerns about wireless radiation, why email doesn't work at some Wi-Fi hotspots, and whether it's worth it to set up a fancy Wi-Fi relay when plain old copper will do.

Our monthly Q&A series offers advice to those seeking help with home or small business WLANs. This month our guru offers some insight into concerns about wireless radiation, why email doesn't work at some Wi-Fi hotspots, and whether it's worth it to set up a fancy Wi-Fi relay when plain old copper will do.

Would you like to ask the guru a question? Write the editor.


Questions about health issues related to Wi-Fi have been in the news lately due to a story out of Simcoe, Ontario, a town outside of Toronto, Canada. There, some parents have asked for the school to shut off their wireless routers claiming that their children have reported symptoms including headaches and dizziness. After meeting on the subject, the school board recently elected to deny the parents' request and continue operating the wireless network.

Looking past the simple observation that kids have a long and storied tradition of finding reasons to stay out of school, the fears about wireless radiation expressed by these parents have been raised before. Disturbingly, none of the people taking such a strong stand on the possible health effects of wireless networks seem to have the slightest grasp of the facts.

The question often raised by Wi-Fi fearmongers is "do we really know the effects of wireless radiation?" And on its face, this question is a fair one. The problem is that, regardless of how we explore the answer, focusing on Wi-Fi is utterly nonsensical. We live in a veritable soup of electromagnetic radiation. It comes from cell phones, FM radio, TV signals, power lines inside and outside our homes, our cordless phones, microwave ovens, x-rays, MRI's, and even the Sun and Earth themselves. And every one of these sources is more powerful than Wi-Fi, sometimes by an order of magnitude measured in thousands and millions.

To put Wi-Fi radiation into perspective, consider that a year of exposure to Wi-Fi is about equal to 20 minutes on a mobile phone. I will not venture here to weigh in on the health effects of RF in general; the point remains, whether or not RF can be harmful to us at certain power levels, we are exposed to a giant helping of it on a continual and daily basis from myriad sources, of which Wi-Fi represents a mere morsel.

Should I just pay $6,000 and have my house wired, or try to rig something up with Wi-Fi?

Q:I live in a rural area near Cincinnati, Ohio. Both the cable and telephone companies are willing to run cable to the house for between four and six thousand dollars. There are hills blocking line of sight for cell and wireless, so no signal at home. How do I get an access point? Do I then use repeaters to link to a WLAN in my house? - Paul

A: In principle the answer here is yes, you can use a combination of directional antennas and wireless repeaters to cover hilly terrain over a long distance. But of course setting up such infrastructure may not be easy, or cheap. You'll need power to the repeaters, not to mention stable, weatherproof mountings, and very accurate calculations to be sure that the signal path can clear the necessary elevations and obstacles. Without knowing much more detail about your topography it is difficult to get more specific.

With all that said, I'm going to risk my Wi-Fi Ambassadorship and instead make this recommendation: pay the six thousand dollars.

First of all, I say this because I'm jealous: I live in a rural area with lots of hills, too. Me and my 19 neighbors are within 3/4 mile of the cable line, and Time Warner (yes I'm naming names) wants over $40,000 to run cable to our houses. So from where I'm sitting, $6,000 is a bargain.

I know that many people complain about their cable broadband service, but the reality is that it may be the best you can do at this moment in time. Your bandwidth will most likely be faster, more reliable, and probably cheaper than building out a long distance wireless link just to serve your own house -- even if your amortize the up-front cost to the cable company.

Why isn't email working at this Wi-Fi hotspot?

Q:I'm at a campground and am connected thru their Wi-Fi .The problem is that I can receive email to my inbox Windows Mail, but I cannot send from Windows Mail. I have no problem sending email if I go to my carrier (Comcast) website. Why must I do that or is there a setting I can make in Windows Mail to allow outbound email. - Judy

A: Strictly speaking Judy, this is not a wireless networking problem, but it is a problem that mobile users may encounter with some frequency so it's worth a chat.

First, an educated guess--your provider (Comcast) is probably blocking the outgoing email port from users who are not on the Comcast network. When your computer tries to "talk" to another computer on the Internet, it does so by means of a specific "port" - think of a port as an individual apartment within a large building. Your computer needs to knock on the right "door" to access a particular service.

Outgoing email is sent using the SMTP protocol, which typically operates on port 25. Many network firewalls will block connections on port 25, often to prevent spammers from abusing their network. In this case, Comcast does not want people outside their network abusing the SMTP port; when you are at home, you are on Comcast's connection and so your outgoing email is allowed through. But at the campground, you are probably using a different provider, and so Comcast is blocking you from accessing port 25.

The reason you can send mail using Comcast's webmail service is because in this case, your machine is not actually sending the email. You are typing the message into your web browser, but Comcast's web server is sending out the email; in other words, the message is going out from within Comcast's network, and so the block does not apply.

There are three possible solutions in this situation:

  1. Find out if your provider offers an "alternate" SMTP port. For example, Comcast offers an alternate SMTP port at 587, which requires authentication. You can configure Windows Mail (or any email client) to connect to this port instead.
  2. Use a different SMTP provider. You do not have to send outgoing email by the same provider where you receive incoming email. For example, you can sign up for a free Gmail account and configure your email client to send outgoing mail via Gmail, even if you do not use Gmail to receive mail.
  3. Use your provider's webmail when you are outside their network (not as robust, but does not require any configuration changes).

Because wireless users are likely to be mobile and therefore sometimes outside their provider's network, it can make your life easier to find an SMTP configuration that will work no matter where you are.



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