Petrichor is a word used to describe that pleasant smell you get after a heavy rainfall. It can be especially strong if the rain comes and ends a long hot dry spell.
If you are out on the land, it really can be delightful, as several different smells merge into one bouquet. There is the clean fresh smell of the air, particularly if there was a little thunder and lightning and the air is charged with ozone. There is a wonderful earthy smell as all the microbes and organisms living in the soil come back to life. There is a sweet pleasant smell of essential oils as the plants, mosses, lichens and fungi, which all suck up water and have a growth spurt. Even the ponds and give off a wonderful watery smell.
I have often been out in the bush after a big rain fall and thought to myself "Wow does it ever smell nice right now." In town or close to civilization, not so much, because believe it or not, humans are pretty smelly creatures.
Things often smell more when they are wet and when the sun is drying them off. Just imagine a big smelly dog that gets wet. A lot of people were complaining about the way Yellowknife smelt, after a big rain we had on July 3. Some were asking where the smells might be coming from.
If you are in the right part of town and the wind is in the right direction, you could be getting the smell of the roiled-up sewage at Fiddler Lake, which is Yellowknife's current sewage lagoon. Or it could be smells from Kam Lake or Niven lake which were used as city sewage lagoons in the past. Before that I believe there were pits here and there, where people dumped their garbage and honey buckets.
So, if you are smelling sewage that could be the cause. Also, swampy areas smell more swampy after a rain. Garbage dumps smell more garbage after a big rain. There is the current dump, the old Niven Lake dump, and the even older dump under Fitz Theil ballpark.
Years ago, I went down to City Hall and asked to see a map showing where all of Yellowknife's former garbage and sewage dumps were. I was told no such map existed. The city seemed to rely on people's memories. Sitting in the Miner's Mess one day, people were talking about a new school being built. One of the old timers said, "They better watch out where they dig, because once upon a time, that used to be a pit for honey buckets." I really don't think the city should rely on old timers' memories. They should be on a map.
Now think of all the dog poop laying just off the trails or in the bush that will smell when it gets wet. Plus, all the places like alleys and green spaces where people poop, urinate and throw up. Once it gets wet it smells. To that you can add in the vehicle exhaust. We are sitting on a greenstone volcanic belt of rocks which have a lot of sulfide minerals in them: when they rust or weather, they have a smell to them. Yes, some rocks do indeed smell. Throw in a little forest fire smoke and yup, Yellowknife does smell, particularly after a rain and some would say it can be less then delightful.
This is true not just of Yellowknife but for every community in the NWT and even all of Canada. Lots of critters have a far better sense of smell than humans, so those odours must form an unpleasant fog for 20 or 30 kilometres around us. As one old timer said, if you can smell it, it wouldn't be long before you will be able to taste it and are you sure you want to be putting that stuff in your lungs and stomach?
These are a few of the things the people looking after air quality should be thinking about. They could come up with a Petrichor Index, rating how the air smells, ranging from the horrendous to the delightful. Why not? Might spur people to clean up the place.
