I get poison ivy easily and badly, and most of the trees I cut on my property have 2-3" vines, so I can tell you what I do. I'll give the whole method for cutting and cleaning in case it will help someone else.
First, I assume that no matter how careful I am, I'll get some poison ivy, so I see my doctor to replenish my stock of steroidal skin cream (triamcinolone acetonide 0.1%). Forget the OTC poison ivy creams, they're worthless. I also pick up some <a href="http://www.ivyblock.com/">Ivy Block,</a> the active ingredient of which is <a href="http://www.nlm.nih.gov/medlineplus/druginfo/meds/a607074.html">bentoquatum.</a> Slather bentoquatum cream on exposed skin before poison ivy exposure, and it will block a mild exposure or lessen a bad exposure.
Dress appropriately. Obviously it's better to get poison ivy on your clothes than your skin. Pay special attention to places that will catch wood dust and chips, like glove cuffs and collars. Once wood chips get inside a sweaty glove, all bets are off. The offending compound of poison ivy is <a href="http://nac.tamu.edu/x075bb/caddo/poison.html">urushiol,</a> which is actually a mixture of several oily compounds. These oils aren't like engine oil, they have some water solubility, so they can diffuse through sweat. Get the oils on sweat soaked jeans, and they diffuse right to your skin - another reason to wear chaps.
Keep your chain razor sharp so it's throwing chips instead of dust. Sometimes I'll sharpen a chain two or three times on one tank of gas when working on poison ivy infested trees. Work quickly. Saw enough to remove the ivy affected parts of the tree, or the worst parts. Once exposed, you have half an hour at the most to wash off the urushiol. the hotter and sweatier you are, the less time you have, so work around poison ivy in the winter if possible.
Cleaning the saw isn't so bad if you maintained a razor sharp chain. Keep your cutting gear on and wear a face shield and breathing mask. Blow out all areas of the saw with compressed air, outside and at arm's length. Then dampen a rag or paper towel with a solvent like kerosene or WD-40 and wipe down the saw, turning the rag frequently. That's it, the saw is clean.
Phase one is complete, clean the saw, which moves us on to phase two, clean yourself.
First, off with the chaps, these stay in the garage and are always handled as if they are contaminated. The clothes come off and go straight in the washer, which you left open before going out, without touching the floor. Everything goes in, leather gloves, hats, boot laces. Try to use an extra pair of boots so you don't have to clean them up, too. Start up the washer after a shower, no need to contaminate the lid or knobs.
The expensive poison ivy designer soaps are snake oil. Urushiol covalently binds to skin cell membrane proteins within half an hour of exposure, after which no soap can possibly remove it. Soap will only wash away unbound urushiol. It is important to use a "stringent" soap, i.e., one that leaves your skin uncomfortably dry. Bath soap, even without moisturizing lotion, is ineffective, it is designed to be used daily and is not stringent. A good, cheap soap to use is grease cutting dishwashing detergent without lotion, Fels Naptha Soap is also a good stringent soap. For the hair, shampoo can be used, but make sure it's the "deep cleaning" stuff - no 2 in 1 conditioner bullsh!t. This next part sucks: we want to keep the skin pores closed so they don't let in more urushiol. That means a cold shower. Step in and buck up. Wash parts known to be exposed first, rinse out the washcloth, then hit the rest. Don't do anything stupid, like washing your junk right after an exposed area.
All that's left now is waiting. In one or two days the rash will develop, or not. Regardless of precautions, I've never escaped a rash, but it's usually an annoying one instead of a horrific, oozing, life-altering affliction. Beware: without warning, sensitivity can develop in people who "don't get" poison ivy, or in those already sensitive, sensitivity can increase. Poison ivy can even <a href="http://nac.tamu.edu/x075bb/caddo/poison.html">kill via skin exposure:</a>
<blockquote> It takes one or more exposures to develop sensitivity but in six days after any exposure a body can be sensitized. This means is that there are people like the teacher who used to show (off) for his students how he could stroke and even chew poison ivy leaves. I guess this was a sort of a, "do as I say, not as I do" lesson. He did this for several years until the year he ended up in the hospital. There is also a record of a lady dying from poison ivy. She was only exposed to the sap every year while washing her husband's hunting clothes. After several years she died due to a severe reaction resulting in a kidney shutdown (Michael Ellis, Jan. 1986).</blockquote>
Don't leave the clothes in a pile for your mother or wife to pick up. If you're man enough to load wood into a trailer, you're man enough to load clothes into a washer.
Links:
<a href="http://nac.tamu.edu/x075bb/caddo/poison.html">The Toxicodendrons.</a> Good general info site.
<a href="http://www.cattail.nu/ivy/ivy_index.html">Poison Ivy Tutorial.</a> Identification.
<a href="http://waynesword.palomar.edu/ww0802.htm">Waynes Word.</a> A technical primer on urushiol. Deals with poison oak, but the urushiol info is applicable to poison ivy.