Frederick County air quality information - February 9, 2012 - 1:59 PM
Current Air Quality Index (AQI) for Particle Pollution
| 16 |
More on the Measurements
Because the Air Quality Index is calculated from past and current measurements, a single measurement does not correspond directly to a particular AQI. However, one measurement can predict what the final AQI level is likely to be. Here are some approximate ranges that can help you understand what these measurements mean.
Ozone (parts per billion)
| 1-hour | 8-hour | AQI Level |
|---|---|---|
| 0-65 | 0-59 | Green |
| 66-82 | 60-75 | Yellow |
| 83-104 | 76-95 | Orange |
| 105-125 | 96-115 | Red |
| 126 and up | 116 and up | Purple |
Eight-hour thresholds are lower because prolonged exposure increases the potential for health problems.
About Air Quality Measurements
This air quality information is collected from DEQ air monitoring stations across Virginia on an hourly basis. These stations measure the amount of ground-level ozone and particle pollution in the air at a specific time.
Not all stations monitor both types of air pollution. All available data for each station is displayed on that station's individual page.
Ground-level ozone is measured in parts per billion. A reading of 100 PPB means that 0.00001 percent of the air around the monitor is ozone gas. An average reading of 85 PPB over eight hours indicates an unhealthy level of ozone.
Particle pollution is measured in micrograms per cubic meter. A microgram is one millionth of a gram, or 0.000001 grams. The web pages for monitoring stations that have particle pollution monitors display only the particle pollution index (a value calculated from several hourly readings).