Usually when I leave Canada I've used most of the cash I had and if (like the last trip) I take a cab to the airport then the cabbie gets an odd tip with lots of change (and probably a bit higher than usual.) In the 1980s I made many trips into Mexico and had some cash I held onto for future trips, then in 1994 they devalued and changed their currency and I don't think it's worth anything. So don't keep it if you can spend it before leaving the country. (When I worked at Organ Pipe Cactus Natl. Monument in Arizona my aunt and uncle from Calgary visited, and I rounded up all of the spare change and bills that we had collected in our various donation boxes and they bought it from us to take it off of our hands, because the bank wouldn't take it.)

Interesting interview on the NPR program Fresh Air today, looking into allergies and how gut and skin health are part of it (how we eat foods now that don't resemble the foods our gut flora evolved digesting.) Allergic: Our Irritated Bodies in a Changing World. I think it was released today. Dr. Theresa MacPhail is the author.

Medical anthropologist Theresa MacPhail, herself an allergy sufferer whose father died of a beesting, set out to understand why. In pursuit of answers, MacPhail studied the dangerous experiments of early immunologists as well as the mind-bending recent development of biologics and immunotherapies that are giving the most severely impacted patients hope. She scaled a roof with an air-quality controller who diligently counts pollen by hand for hours every day; met a mother who struggled to use WIC benefits for her daughter with severe food allergies; spoke with doctors at some of the finest allergy clinics in the world; and discussed the intersecting problems of climate change, pollution, and pollen with biologists who study seasonal respiratory allergies.