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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: 21010

Reported Deaths: 355
CountyConfirmedDeaths
Multnomah484994
Washington304725
Marion288370
Umatilla225128
Clackamas152340
Malheur76814
Deschutes59610
Lane5793
Jackson4612
Yamhill45013
Lincoln4149
Union3942
Jefferson3554
Morrow3543
Polk31312
Linn27710
Klamath2012
Wasco1893
Hood River1840
Benton1696
Douglas1501
Josephine1142
Columbia940
Coos910
Clatsop850
Crook471
Baker380
Tillamook340
Lake320
Wallowa191
Sherman160
Curry150
Harney100
Gilliam40
Grant40
Unassigned00
Wheeler00

California Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 554388

Reported Deaths: 10307
CountyConfirmedDeaths
Los Angeles2067784967
Riverside40452799
Orange39076720
San Bernardino35452502
San Diego31779586
Kern22626171
Fresno17031171
Alameda13213208
San Joaquin12303211
Santa Clara11475203
Sacramento10795161
Tulare10475196
Imperial9693244
Stanislaus9566161
Contra Costa9022138
Ventura814689
San Francisco743267
Santa Barbara670469
San Mateo6110120
Marin528779
Monterey521235
Merced501264
Kings445356
Solano402940
Sonoma343147
Madera230239
Placer218620
San Luis Obispo209315
Yolo169043
Santa Cruz12386
Butte10958
Napa104610
Sutter9217
El Dorado7291
San Benito7094
Lassen6380
Yuba5884
Shasta41810
Mendocino38010
Colusa3624
Glenn3603
Nevada3221
Humboldt2824
Tehama2761
Lake2202
Amador1642
Mono1531
Tuolumne1522
Calaveras1471
Del Norte990
Siskiyou930
Inyo643
Mariposa602
Plumas340
Modoc50
Trinity50
Sierra30
Alpine20
Unassigned00
Medford
Clear
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Hi: 94° Lo: 57°
Feels Like: 90°
Brookings
Clear
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Hi: 94° Lo: 61°
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Crater Lake
Clear
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Grants Pass
Clear
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