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O2 local forecast

Washington, D.C.

Reading the local forecast...

AQI — · N/A · cleanest at loading

Washington, D.C.

Measured

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US AQI

No data

No recent measurement available near this location.

PM2.5

—µg/m³

PM10

—µg/m³

O₃

—µg/m³

Measured

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O2 broadcast

Preparing local bulletin

low confidence

O2 is assembling the latest report from validated AQI and forecast data.

Validated transcript ready

Transcript

Good evening, Washington. Here's your O2 air update.

Local air-quality data for Washington is still loading.

O2 is still waiting on enough hourly forecast data to call the next safer outdoor window.

Here's what to do. No recent AQI reading is available. Check local conditions before outdoor plans.

No local air-quality alert is active for this spot right now.

This update draws on Open-Meteo CAMS. Confidence in the timing is low.

Sources: Open-Meteo CAMS.

Ask the map

Select a question above.

Provenance

Data sources

Open-Meteo · CAMS
PM2.5 / PM10 / O₃ hourly + 48h forecast
Modeled
NIFC WFIGS
Current interagency fire perimeters & incidents
Measured
NWS NDGD Smoke
Hourly North America surface-smoke forecast
Modeled

Smoke layers · advanced

US model · NDGDNWS surface smoke — covers US & CanadaCanada model · FireSmokeUBC BlueSky full model — cyan overlay

Layer either model on its own, or overlay both. The Canada model renders in cyan so you can tell the two apart where they meet.

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How to stay safe

The same fixed rules O2 uses to read your air. Every category is written out as well as colored.

US AQI categories, their ranges, and the guidance O2 applies to each
Category	AQI	What O2 advises
Good	0–50	Air quality is satisfactory.
Moderate	51–100	Unusually sensitive people should consider reducing prolonged outdoor exertion.
Unhealthy for Sensitive Groups	101–150	Sensitive groups should reduce prolonged or heavy outdoor exertion.
Unhealthy	151–200	Everyone should reduce prolonged or heavy outdoor exertion.
Very Unhealthy	201–300	Everyone should avoid prolonged or heavy outdoor exertion.
Hazardous	301–500	Everyone should avoid all outdoor exertion.

When smoke is at ground level

Keep windows and doors closed while smoke is at ground level.
Run an air purifier with a HEPA filter, or set your HVAC to recirculate rather than drawing in outside air.
If you have to be outside for a long stretch in Unhealthy conditions or worse, a properly fitted N95 or KN95 reduces how much smoke particulate you breathe. A cloth or surgical mask does not.
Move workouts indoors, or shift them to the cleanest window on the timeline.
Check on neighbors who are older, live alone, or have heart or lung conditions.

When to get medical help

Contact a medical provider if you have chest pain, real difficulty breathing, or symptoms that do not ease after moving to cleaner air. If symptoms are severe, call 911.

O2 provides general information only and is not medical advice. Always follow guidance from public health and emergency management authorities.

Frequently asked questions

Using O2

Is it safe to go outside right now?

Check the current category at the top of the page. O2 states it in words as well as color, and pairs it with guidance for everyone and for sensitive groups.

If you are planning exercise or a long stretch outdoors, use the safest window O2 names rather than the reading alone. Conditions this afternoon are not always conditions tonight.

What does the AQI number mean?

The Air Quality Index is the standard United States scale for reporting air quality. It runs from 0 to 500, and lower is better. 500 is the top of the scale — anything from 301 upward is the “Hazardous” category, dangerous for everyone.

Some apps report numbers above 500 by extending the formula past the official ceiling. O2 stays on the official 0–500 scale, so a reading here is always comparable to what agencies publish.

Every category on this page is written out as well as colored, so the meaning is clear without relying on color vision.

The map shows smoke over me but my AQI is Moderate. Which one is wrong?

Neither. They measure different things. The smoke layer shows smoke anywhere in the air column above you, from the ground up to several miles high. The AQI measures air at ground level, where you actually breathe.

Smoke from distant fires often travels a mile or two above the surface. When the map shows smoke overhead and your AQI stays low, that smoke has not mixed down to you.

It can still arrive later. As the day warms, the lower atmosphere mixes and smoke aloft can be drawn to the surface, which is why air often worsens in the afternoon and eases after sunset. That mixing is what the 48-hour forecast tracks.

Why can I smell smoke when the reading is only Moderate?

Your nose is more sensitive than the instruments. People can smell wood smoke well below the concentrations that move the AQI.

Your eyes take in the whole sky, too. A thin haze spread over many miles makes the sky look milky and the sun look red without the air at street level being heavily polluted.

A smoke smell is worth noticing, but on its own it does not mean the air is unhealthy.

Why does O2 differ from AirNow or my weather app?

AirNow reports readings from physical ground monitors. O2 uses modeled data, which estimates conditions everywhere, including places with no monitor nearby.

Monitors are more precise at their exact location. Models cover everywhere and can forecast ahead. Small differences are normal; large, persistent ones are worth reporting.

For official readings and health guidance, see AirNow.gov, Weather.gov, and your state or local health department. O2 is an independent tool and is not affiliated with the EPA, NOAA, or any government agency.

A friend's app showed a totally different — or much higher — number. Why?

Not every app is on the same scale. O2 uses the official United States EPA Air Quality Index, which runs 0 to 500. Some apps and monitors use other scales — a few extend well past 1000 during extreme events, and other countries use entirely different indices — so the same air can read 175 here and a far larger number elsewhere.

O2's readings come from Open-Meteo, built on CAMS, the Copernicus Atmosphere Monitoring Service — a science-grade global model run by the EU's ECMWF. Because it is one consistent method applied everywhere, O2 gives you a comparable 0-to-500 reading anywhere in the country, including places with no monitor nearby.

A single ground monitor can be more precise at its exact spot, but coverage is patchy and scales vary. When two sources disagree, check which scale each one uses before assuming either is wrong.

What does O2 do with my email and location?

You can use the whole dashboard without giving O2 anything. Your location is used to show your local forecast.

Air alerts are opt-in and need an email address. If you subscribe, O2 stores your email, the latitude and longitude you chose, a label for that place, and its timezone. That is what makes a local alert possible.

Subscriptions are confirmed by a link sent to your address, so nobody can sign up someone else. Every message carries one-tap unsubscribe, and unsubscribing stops all future mail. O2 does not sell your details.

How it works

Where does the data come from?

Air quality and forecasts come from Open-Meteo, built on the CAMS global atmospheric model. Fire perimeters and incidents come from NIFC WFIGS. Modeled surface smoke comes from the NWS NDGD forecast, with the Canadian FireSmoke BlueSky model available as an optional overlay. Basemaps are Mapbox and OpenStreetMap.

The air-quality, fire, and smoke sources are listed on the dashboard under Data sources, each with a link and a label showing whether it is measured or modeled.

How does wildfire smoke change PM2.5, PM10, and ozone?

Wildfire smoke is mostly PM2.5 — fine particles small enough to reach deep into the lungs and the bloodstream. PM2.5 is the pollutant smoke raises most, and usually the one driving the AQI during a smoke event.

Smoke also carries coarser PM10, such as ash, though PM2.5 is normally the bigger health concern. And smoke is not only particles: it contains gases and chemical precursors that, in sunlight, can push up ground-level ozone (O₃) downwind — so a plume can worsen ozone in places the particles never reach.

O2 lists PM2.5, PM10, and O₃ under the reading so you can see which one is driving your air quality.

Does the NOAA briefing track dust too, or only smoke?

NOAA's Hazard Mapping System — the source of the written smoke briefing — analyzes both wildfire smoke and wind-blown dust from satellite imagery. They are different hazards: smoke comes from fires, dust from dry, exposed ground lifted by strong winds.

O2 is built around wildfire smoke, so its map layers and forecast focus on smoke. The NOAA briefing text may still mention dust where analysts see it, and that distinction is theirs.

What is the difference between observed and forecast?

Observed describes conditions up to now. Forecast describes what the models expect next, out to 48 hours.

The timeline marks the boundary between the two, so you always know whether you are looking at what happened or what is expected.

You will also see labels on the sources themselves. Measured means the value is a reading of current conditions. Modeled means it is produced by an atmospheric model rather than read off an instrument at your location. Forecast means it describes a time that has not happened yet.

How is the improvement time calculated?

O2 walks the hourly forecast for your location and finds the first hour when conditions are expected to cross into a better AQI category, then states it in plain language.

It also names the cleanest window in the loaded forecast, which is often later than the moment things first start improving.

Forecasts are estimates and get less certain further out. Wind shifts and new fires can move the timing by hours. Treat it as planning guidance, not a guarantee.

What does the confidence rating mean?

It reflects how much usable forecast data O2 actually loaded for your location and how clearly that data supports a timing estimate.

When coverage is thin or the signal is ambiguous, confidence drops and O2 says so rather than stating a precise time it cannot support.

Is O2 usable with a screen reader or a keyboard?

Air quality is safety information, so reading it should not depend on seeing a map or telling colors apart. These are the specific things that have been checked.

Every air-quality category is written out in words beside its color, so nothing depends on color vision alone. The current reading, its category, and the time the air is expected to improve are all available as text, not only as map graphics.

The timeline, the map questions, the alert signup, and every question on this page can be operated from the keyboard, and the control you are on is always visibly outlined. O2 also honors your system's reduce-motion setting.

Reading the local forecast...

Preparing local bulletin

Data sources

Smoke briefing

NOAA smoke description

How to stay safe

When smoke is at ground level

When to get medical help

Frequently asked questions

Using O2

How it works