How to Estimate Air Quality Only Using Your Eyes

The 5-3-1 index can help you understand and estimate the air quality at any time, from any location.

Posted: Jul 23, 2018 7:52 PM

MEDFORD, Ore. -- Wildfires are burning in remote areas, sending smoke across almost all of southern Oregon.  While the Department of Environmental Quality monitors air pollution throughout the state, not every community has an official monitoring station. Even where there is an air quality monitoring site, smoke levels can rise and fall more rapidly than the monitoring sites can update.  Those are reasons why experts recommend visual observations for air quality health alerts.

Experts say the "5-3-1 visibility index is a simple way of estimating smoke levels and what precautions to take." While this method can be a useful tool, it's not 100% accurate.  You start by determining how many miles you can see, based on your knowledge of the distance to a mountain, signage, or other landmark. The DEQ suggests "a general rule of thumb: if you can clearly see the outlines of individual trees on the horizon it is generally less than five miles away."  They recommend positioning yourself so the sun is behind you.

Once distance has been determined, follow this simple guide:

5

If visibility is well over five miles, the air quality is generally good.

Even if visibility is five miles away but generally hazy, air quality is moderate and beginning to deteriorate, and is generally healthy, except possibly for smoke sensitive persons. The general public should avoid prolonged exposure if conditions are smoky to the point where visibility is closer to the 5-mile range.

If under five miles, the air quality is unhealthy for young children, adults over age 65, pregnant women, and people with heart and/or lung disease, asthma or other respiratory illness. These people should minimize outdoor activity.

3

If visibility is under three miles, the air quality is unhealthy for everyone. Young children, adults over age 65, pregnant women, and people with heart and/or lung disease, asthma or other respiratory illness. These people should minimize outdoor activity.

1
If under one mile, the air quality is unhealthy for everyone. Everyone should avoid all outdoor activities.

No matter how far you can see, if you feel like you are having health effects from smoke exposure, take extra care to stay inside or get to an area with better air quality. You should also see your doctor or other health professional as needed.

Oregon Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 3967

Reported Deaths: 148
CountyConfirmedDeaths
Multnomah105258
Marion91425
Washington69817
Clackamas29610
Deschutes1200
Linn1159
Umatilla1123
Polk9610
Lane672
Yamhill667
Jackson600
Benton555
Clatsop450
Klamath410
Coos310
Malheur280
Josephine251
Douglas250
Jefferson240
Wasco181
Columbia160
Hood River120
Morrow120
Lincoln90
Tillamook60
Crook60
Curry60
Union60
Wallowa20
Sherman10
Grant10
Harney10
Baker10
Unassigned00

California Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 99387

Reported Deaths: 3819
CountyConfirmedDeaths
Los Angeles478452145
Riverside7139303
San Diego6797249
Orange5578131
San Bernardino4567176
Alameda298693
Santa Clara2675139
San Francisco239940
San Mateo190482
Kern187629
Tulare177179
Santa Barbara155112
Fresno148222
Contra Costa135337
Imperial135224
Sacramento131056
Ventura91230
San Joaquin77133
Kings6882
Stanislaus65928
Sonoma5154
Solano45520
Monterey4298
Marin41714
Merced2687
San Luis Obispo2631
Santa Cruz2002
Yolo19822
Placer1889
Napa1093
Humboldt942
Madera852
El Dorado780
San Benito762
Sutter422
Nevada411
Butte400
Del Norte400
Shasta364
Mono341
Yuba281
Mendocino220
Inyo191
Mariposa161
Lake140
Calaveras140
Glenn120
Amador100
Siskiyou61
Colusa50
Plumas40
Lassen40
Tuolumne30
Tehama31
Alpine20
Trinity10
Sierra10
Unassigned00
Medford
Clear
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Brookings
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