There are few home improvement projects as dangerous as roof stain removal. So many different things can go wrong that it would take a novella to describe all the hazards in detail. That said, I'd like to go over some of the more common dangers that one might encounter while cleaning a roof.
First of all, it's so important to be aware of power lines that run from the street to your roof. Take a few minutes before starting to locate exactly where the line is so that you can raise the ladder in a different area if possible. If you absolutely must mount the roof near a power line then try to use a non-conducting ladder in case it moves or slips. Also be cognizant of the fact that if you slip or begin to fall in this area that it would be unwise to grab the line for support. Electrocution is a very real and present danger. Try to grab a gutter, instead. You might rip the gutter off the home but at least you'll come away alive. Safe roof stain removal is all about lowering the odds of a nightmare scenario, and one can certainly help to make this possible by simply avoiding the part of the roof where the power line connects.
Once on the roof there are a whole host of other potential issues to be aware of. It should go without saying that the steeper the roof the higher your odds of a disastrous fall. Use the proper equipment to ensure your safety. You should have roofing shoes with top-tier traction and it would also be wise to use a safety harness system if you have any doubts whatsoever. Keep your center of balance as low as possible so that if you begin to slip you can more easily drop down and grip the surface.
There's one trick in particular that will make your navigation of the roof surface more safe. Walk the chemical hose to the furthest point of the roof from the ladder first and work your way back from there. That way the chemical-covered (and very slippery) portion of the roof is always behind you and you will be walking on dry shingles the entire time. Don't forget to leave yourself a dry path back down to the ladder area. Also, always make a note of where the chemical hose is at any given time. I've had a number of close calls myself where I've tripped over the hose and nearly tumbled off the roof completely. Roof mold removal projects require your complete attention and focus at all times, not only so that the cleaning is a success but also so that you don't make a wrong move that results in a horrifying fall.
An article about roof stain removal safety wouldn't be complete without mentioning the protection of your body from chemicals. Roof cleaning solutions are very powerful, both in liquid and gas form, and you absolutely must take the proper precautions. Wear a NIOSH-approved mask while mixing and applying the product to protect your lungs from exposure. Also, wear a comfortable pair of goggles to protect your eyes and some elbow-length gloves to protect your hands and forearms. I also recommend long sleeves and pants to prevent the exposure of other parts of your body.
As should now be evident, roof cleaning is such a dangerous activity that it should really be left to trained professionals. If at all possible try to find one who uses non-pressure methods and is fully insured. Expert roof stain removal specialists already have the tools and experience necessary to complete the job safely and in a timely fashion.