We haven’t seen much of the sky lately. I long for some clear, blue days! I know that sitting in a smoky cesspool is a lot better than evacuating or watching my community burn so I’m trying not to be too down. But, boy-howdy, it is foul out there:

If you aren’t tuned in to Purple Air, you should be. It is a network of air quality sensors that you can freely access via the internet or a mobile device. We can simply look outside and see that the air is horrible. But that’s the stuff you can see. There are lots of things we are breathing in that we cannot see. These are the really bad things. In fact, we often have days where the air quality looks fine but is actually not. Sometimes you see a slight “haze” which can be the result of high concentrations of really small particles.

The Purple Air sensors measure several things but the one of interest is abbreviated PM for “particulate matter.” In this case, size matters. The sensors measure particles less than 10 microns in diameter and particles less than 2.5 microns. (A micron is also called a micro-meter, which is 10^-6 or 0.000001 meters, about 0.00004 inches.)

It’s the PM 2.5 number that’s displayed. You can see that this morning the Yreka sensors show the local air quality to be very bad with numbers approaching 300. That means 300 micrograms per cubic meter (µg/m³) of air. Anything over 100 is a health concern. Here’s the scale:

Small particles are inhaled and deposit themselves on the lungs and from there enter the bloodstream. It almost doesn’t matter what the source of the particles is, the size is what makes them a problem. Wildfire smoke is a good source of particulate matter. Power plants and vehicle exhaust are also primary sources. These particles can be made of hundreds of different chemicals, including things like metals, and they spread indiscriminately. We’ve all sat around campfires and breathed in the smoke and not thought much about it. But this is like having a campfire in your tent with you at night and then carrying it around with you all day long. No one does that! So please don’t think that just because forests are “natural” that means that forest fires are good for your lungs. (Here’s a good article about the health effects of particulates.)

The EPA website has a good primer about particulate pollution. If you have N95 masks you might consider wearing them if you are going to be outdoors. They can help block some of the small (1-3 micron) stuff. Here’s a graphic to give you a sense of scale:

Stay safe out there and pray for rain, I suppose, or at least a good stiff wind to clean out the valley!