Salty your message box is full so I can't reply to you, however I figured I would share this with the group because it is relevant.
Hello. The issue right now is the rough fire. Here is the link to help with the fire restrictions.
http://inciweb.nwcg.gov/unit/797/
Yosemite Fire Info:
http://www.nps.gov/yose/blogs/fireinfo.htm
Make sure you have a fire permit
California Campfire PermitsCalifornia campfire permits are required for campfires, stoves and lanterns on the National Forest sections of the JMT. You can obtain one online or at any Forest Service, BLM and Cal Fire office in the state. They may not be available in the National Parks along the JMT as they are not required. http://www.preventwildfireca.org/Campfire-Permit/
The main fire right now affecting the JMT is the rough fire. The JMT is out of harms way however the smoke is being seen as far as 40 miles away and going on average 20 miles high. Your september dates looks like it should be fine due to they are starting to back burn tomorrow in the canyon to burn down the canyon wall to stuff it out, however it can still travel up the canyon floor towards the JMT but it has a long way to go until it gets to the JMT.
As far as breathability bring antihistamines I had to use that on the short hike I did yesterday. I used Afrin because it closes the membranes and allowed my nasal passages to open up.
I would call MTR to see what they are up to. Also are you a member of the JMT face book page? Where are you flying into? If your flying into fresno let me know.
Regards,
Gary