Smoke hanging on over our area; Air Quality Index Very Unhealthy
The wildfire smoke that blankets the region and in fact major parts of the west coast is not expected to improve much this week. People with lung or heart conditions are urged to stay indoors, and avoid physical activity.
As of 9am on Monday the AQI (Air Quality Index) according to AirNow.gov and the "Seattle-Duwamish permanent sensor was 219 ppm (parts per million) which puts it in the Very Unhealthy range. Above 300 is considered Hazardous. The overall area PPM concentration was around 147.
That's expected to persist near these same levels through Wednesday.
The current forecast is for no chance of rain until Thursday, when a 75% chance of rain is expected.
The kind of pollution it is matters as well with the smoke and particulate matter being 2.5. To understand what that means look at this graphic:
Size comparisons for PM particles
information from Environmental Protection Agency
What is PM, and how does it get into the air?
PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.
Particle pollution includes:
- PM10 : inhalable particles, with diameters that are generally 10 micrometers and smaller; and
- PM2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.
- How small is 2.5 micrometers? Think about a single hair from your head. The average human hair is about 70 micrometers in diameter – making it 30 times larger than the largest fine particle.
Sources of PM
These particles come in many sizes and shapes and can be made up of hundreds of different chemicals.
Some are emitted directly from a source, such as construction sites, unpaved roads, fields, smokestacks or fires.
Most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles.
What are the Harmful Effects of PM?
Particulate matter contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. Some particles less than 10 micrometers in diameter can get deep into your lungs and some may even get into your bloodstream. Of these, particles less than 2.5 micrometers in diameter, also known as fine particles or PM2.5, pose the greatest risk to health.
Fine particles are also the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas.