Air quality in Lewiston

Air quality index (AQI) and PM2.5 air pollution in Lewiston

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What is the pollen count in Lewiston today?

Tree pollenModerate
Grass pollenLow
Weed pollenLow
See pollen forecast


What is the current weather in Lewiston?

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WeatherBroken clouds
Wind0 mp/h
Pressure29.9 Hg

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1 Little Rock, Arkansas


2 Hampton, Virginia


3 Lake Charles, Louisiana


4 Elizabeth City, North Carolina


5 Pensacola, Florida


6 Chicago, Illinois


7 Porterville, California


8 Junction City, Oregon


9 Logan, Utah


10 Visalia, California


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Real-time Lewiston air quality ranking

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1 Lewiston PM2.5 BAM


(local time)


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What is the current air quality in Lewiston?

Air pollution levelAir quality indexMain pollutant
Moderate 57 US AQIPM2.5



PM2.5 concentration in Lewiston is currently 3 times the WHO annual air quality guideline value

Health Recommendations

What is the current air quality in Lewiston?

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Sensitive groups should reduce outdoor exercise
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Close your windows to avoid dirty outdoor air
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Sensitive groups should wear a mask outdoors
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Sensitive groups should run an air purifier


Lewiston air quality index (AQI) forecast

DayPollution levelWeatherTemperatureWind
Wednesday, Feb 21

Good 30 AQI US

Human face indicating AQI level
Weather icon
55.4° 41°
Wind rotating 309 degree 6.7 mp/h
Thursday, Feb 22

Good 16 AQI US

Human face indicating AQI level
Weather icon
55.4° 37.4°
Wind rotating 176 degree 4.5 mp/h
Friday, Feb 23

Good 33 AQI US

Human face indicating AQI level
Weather icon
55.4° 41°
Wind rotating 256 degree 17.9 mp/h

Moderate 57 AQI US

Human face indicating AQI level
Weather icon 60%
53.6° 41°
Wind rotating 240 degree 17.9 mp/h
Sunday, Feb 25

Good 5 AQI US

Human face indicating AQI level
Weather icon 90%
48.2° 35.6°
Wind rotating 257 degree 22.4 mp/h
Monday, Feb 26

Good 5 AQI US

Human face indicating AQI level
Weather icon
42.8° 32°
Wind rotating 257 degree 13.4 mp/h
Tuesday, Feb 27

Good 4 AQI US

Human face indicating AQI level
Weather icon 70%
44.6° 35.6°
Wind rotating 178 degree 11.2 mp/h
Wednesday, Feb 28

Good 4 AQI US

Human face indicating AQI level
Weather icon 100%
41° 35.6°
Wind rotating 138 degree 6.7 mp/h
Thursday, Feb 29

Good 4 AQI US

Human face indicating AQI level
Weather icon 90%
39.2° 32°
Wind rotating 121 degree 6.7 mp/h
Friday, Mar 1

Good 4 AQI US

Human face indicating AQI level
Weather icon 90%
37.4° 30.2°
Wind rotating 286 degree 4.5 mp/h

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What is the current level of air pollution in Lewiston, Idaho?

Lewiston is a city and is the county seat of Nez Perce County, Idaho, United States, in the state's north-central region. According to a census conducted in 2010, the estimated population was approximately 32,000 people. This showed a rise of 1,000 people over the past ten years. The city can be found at the confluence of the Snake River and the Clearwater River.

In the middle of 2021, Lewiston was experiencing a period of air that was classed as being “Unhealthy for sensitive groups” with a US AQI reading of 119. It is predicted that tomorrow it will be even worse when it slips into the “Unhealthy” bracket with an estimated reading of 169. This United States Air Quality Index number is an internationally used set of metrics supported by the World Health Organisation (WHO) and is used to compare different cities throughout the world using comparable standards. It is calculated by using the levels of the six most commonly found pollutants. If figures are not all available, the figure is calculated using what information is available. In Lewiston, the only pollutant that was recorded was PM2.5 with a figure of 43 µg/m³. This can immediately be seen to be more than four times higher than the recommended level of 10 µg/m³ by the World Health Organization (WHO). Whilst no level of air pollution can be safe, 10 µg/m³ is low enough to be attained by most places with little effort.

With a level as high as this, the advice is to close doors and windows to prevent more dirty air from entering the room. Those of a sensitive disposition are advised to remain indoors or if travel outside is unavoidable, then a good quality particle filter mask is recommended. The use of an air purifier would be beneficial if one is available. The table at the top of this page will help to decide when it is safe to venture outside again.

Does the level of air pollution vary throughout the year in Lewiston?

During the last few days, the air quality in Lewiston has varied between being “Moderate” to “Unhealthy for sensitive groups” to “Unhealthy”, with the US AQI numbers ranging from 93 to 174. This is due to the number of wildfires that are currently burning. There are multiple fires in southern Oregon, Nevada and other parts of the state. More than 61,000 acres are ablaze in Reno, Nevada and northern California and only 9 percent of it is currently contained. The Bootleg Fire is burning more than 143,000 acres near Klamath Falls, Oregon. Several areas here are under evacuation notices in case the situation becomes worse. The one closest to Lewiston and probably the main source of pollution is at Dry Gulch which is raging through 38,000 acres and is only 5 percent contained. The Fire Department of the National Guard has been enlisted to assist the local firefighters. The forecast is not looking good and these conditions are expected to last for the foreseeable future. The location of some of the fires is in very steep terrain which makes them very difficult to control, both from the ground and also from the airborne units.

South of Lewiston, are six fires, which so far have burned a combined 100,000 acres. That smoke is also going into Montana on the prevailing winds.

Looking back at the 2020 figures published by, it can be seen that the period of worst air quality occurred in September when a figure of 52.6 µg/m³ was recorded which classified it as being “Unhealthy for sensitive groups”. There was a marked improvement the following month when the quality improved and fell into the “Good” category with a figure of 10.8 µg/m³. For the remaining ten months of the year, Lewiston achieved the target figure as recommended by the WHO of being less than 10 µg/m³. June in particular returned a very low figure of 3.9 µg/m³.

Historically, records were first kept in 2017 when the annual mean figure was 11.4 µg/m³ which would be classified as being “Good”. The following year saw the figure dip below the WHO recommendation with 8.3 µg/m³, and yet again in 2019 when the figure was even lower at 7.5 µg/m³. In 2020, the figure rose again up to 10.5 µg/m³ which put it above the target figure back into the “Good” classification. This is unusual and as such may not be a truly accurate reflection of reality because of the restrictions imposed due to the COVID-19 pandemic. Many vehicles were no longer used as the drivers were furloughed and not required to commute to and from work. There were also many factories and other non-essential production units which were temporarily closed in an attempt to prevent the spread of the virus.

Has Idaho some of the most polluted areas in the country?

Air quality is getting worse, according to a new report from the American Lung Association, and much of the blame can be attributed to wildfires. It is affecting the entire state. Idaho now has several of the top 25 most polluted areas in the country, which is cause for concern.

The pollution spikes are increasing both in intensity and frequency of occurrence. Many places now experience more days of elevated levels of high particle pollution which is directly attributable to wildfires. No Idaho county in the report received higher than a "D" grade for particle pollution.

Both ozone and particle pollution are dangerous to public health and can increase the risk of premature death and other serious health effects. Particle pollution is made of soot or tiny particles that come from coal-fired power plants, diesel emissions, wildfires and wood-burning devices. These particles are so small that they can travel deep in the lungs and trigger asthma attacks, heart attacks and strokes, and worse. Breathing ground-level ozone can generate a variety of health problems including chest pain, coughing, throat irritation and congestion. It can worsen bronchitis, emphysema, and asthma. Ozone also can reduce lung function and inflame the lining of the lungs. Repeated exposure can lead to permanent scarring of lung tissue.

Where does air pollution come from in Lewiston?

It is generally accepted that there are four main categories of air pollution. These are mobile sources from such things as cars, buses, airplanes, trucks, and trains, or anything powered by an internal combustion engine that operates on fossil fuel. Stationary sources include power plants, oil refineries, industrial facilities and factories. Area sources can be thought of as agricultural areas, cities, and wood-burning fireplaces. The last category is from natural sources which includes wind-blown dust, wildfires, and volcanoes.

Mobile sources are responsible for more than 50 percent of all the air pollution in the United States and the major mobile source of air pollution is the automobile, according to the Environmental Protection Agency. Stationary sources, such as power plants, emit large amounts of pollution from a single location, these are also known as point sources of pollution.

Area sources are generally made up of numerous smaller sources which individually are not considered to be a threat. They pose a problem when their pollution is combined. Natural sources can be significant but do not usually create an ongoing situation in the same manner as the others.

Pollution from human-generated and natural sources is often created in one place and transported through the air to another. Very often, and depending on the type of pollution, a chemical change can take place as one pollutant reacts with others in the presence of sunlight.

Once pollutants become airborne they produce haze which impairs visibility and once they are deposited, they can create harm to the environment. Parks that are downwind of power plants that lack modern pollution controls often suffer from elevated levels of PM pollutants. Exhaust pipe emissions from cars and trucks, as well as industrial processes such as oil and gas development, give rise to higher levels of ozone concentrations, too.

What can be done to improve the air quality in Lewiston?

The Nez Perce Tribe and researchers at Washington State University have received a three-year U.S. Environmental Protection Agency grant to measure air pollution in Lewiston, Idaho.

Formaldehyde is an airborne pollutant that can cause negative health effects such as sore throats and coughs to lung cancer. Formaldehyde can be directly emitted or can form in the atmosphere from reactions of other pollutants to sunlight. Several years ago, researchers measured high summer formaldehyde concentrations of up to 22 parts per billion in Lewiston.

Due to Lewiston’s position so close to the Snake River and the Clearwater River, researchers will monitor downstream and upstream wind flows from Lewiston to determine the pollution’s source. Wind flow along rivers can exacerbate an air quality problem or can help mitigate it.

What are the detrimental effects on human health due to poor air quality in Lewiston?

Poor air quality can irritate the eyes, nose, and throat, cause shortness of breath, provoke asthma and other respiratory conditions, and affect the heart and cardiovascular system. Breathing polluted air for long periods can cause more serious problems.

Children breathe more than adults and are more sensitive to pollution. Their air passages are narrower because of their smaller frames, so it takes less inflammation or irritation to obstruct their airways. Children typically spend more time outdoors and are more active than adults. Due to their lower height, they are also closer to the source of the pollution from vehicles.

Older adults with pre-existing respiratory conditions are at greater risk too. People with diabetes have a possible underlying cardiovascular disease.

Healthy adults of all ages who exercise vigorously outdoors or who are required to be outside because of their job are susceptible to air pollution because they have a higher level of exposure. Exercise causes people to breathe faster and more deeply, drawing more air into the lungs. In the case of ozone, the risk of serious effects is heightened during the afternoon when the sun is at its strongest and ozone levels are at their highest. It’s better to exercise in the morning or evening when ozone concentrations are expected to be less elevated.

Ozone can cause coughing, headaches, and eye, nose, and throat irritation. Symptoms may last for a few hours after ozone exposure and even become painful. Overexposure causes a sunburn-like condition on the lining of the lungs which the body can eventually repair if the exposure is only short-term. Long-term exposure adds stress to the heart and lungs, which must work harder to supply the body with the oxygen it needs.

Ozone pollution is also harmful to the natural world. Trees and other living organisms can suffer from compromised growth, reproduction, and the overall health of plants. Ozone also interferes with the ability of plants to produce and store food. This makes plants and trees weaker and more susceptible to diseases, pests, and environmental stress. Leaves are easily damaged when they become brown and spotty and wilt prematurely, eventually dying and falling off the tree. The yield from growing crops is often much lower when the level of ozone is continuously high. It affects such crops as soybeans, kidney beans, wheat and cotton.

Particulate Matter, or “soot,” is made of microscopically small particles, either solid or liquid or a combination of both. The smaller the particles, the deeper they can penetrate into the respiratory system, which causes more significant health problems. Fine particles with a diameter of less than 2.5 microns can easily bypass filters in the nose and throat and penetrate deep into the lungs where they lodge in the alveoli and are then able to transfer into the bloodstream and travel around the body to other organs. Larger particles less than 10 microns in diameter can cause significant health problems too but are often stopped by the body’s self-defense system in the nose.

The lungs can easily become porous due to excess exposure to ozone pollution. This results in the increased permeability, or the ability of liquids and gases to pass through to the lungs.

Lewiston air quality data attribution

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