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Air Quality
Frederick · updated at 20:00Air Quality Index · US EPA scale
Good
Clean air, no risk for anyone.
Main pollutantO₃52.0 µg/m³25
050100150200300+
Temperature13°Humidity94%Wind13 km/h NNWUV index0
Health recommendations
GoodGeneral population
Great day for outdoor activities. A good time to air out the house.
Sensitive groups
No restrictions.
children, older adults, pregnant women and people with asthma, COPD or heart diseaseOutdoor exerciseGo ahead
WindowsOpen is fine
MaskNot needed
Sensitive groupsNo restrictions
Next 24 hours
hourly AQI25O₃20:00
24O₃21:00
24O₃22:00
23O₃23:00
Tomorrow23O₃00:00
23O₃01:00
23O₃02:00
23O₃03:00
23O₃04:00
22O₃05:00
21O₃06:00
20O₃07:00
20O₃08:00
21O₃09:00
23O₃10:00
24O₃11:00
25O₃12:00
26O₃13:00
26O₃14:00
26O₃15:00
25O₃16:00
24O₃17:00
22O₃18:00
20O₃19:00
Worst at 13:00 26Best at 07:00 20
Next days
daily peak AQISun27/0938GoodO₃
Mon28/0926GoodO₃
Tue29/0963ModeratePM2.5
Wed30/0973ModeratePM2.5
Pollutants now
concentration · sub-indexWhat it isPM2.5
Fine particles under 2.5 µm — small enough to reach the lungs and bloodstream. They come from wildfires, diesel engines, industry and smoke, and are the pollutant most linked to heart and lung disease.
WHO 2021 guideline: 15.0 µg/m³ (24-h mean)What it isPM10
Inhalable particles up to 10 µm: road and construction dust, pollen, soot and sea salt. They irritate the nose, throat and airways and worsen asthma and bronchitis.
WHO 2021 guideline: 45.0 µg/m³ (24-h mean)What it isOzone (O₃)
Ground-level ozone forms when sunlight reacts with vehicle and industrial gases. It peaks on hot, sunny afternoons and causes coughing, chest pain and reduced lung function during exercise.
WHO 2021 guideline: 100 µg/m³ (24-h mean)What it isNitrogen dioxide (NO₂)
A gas produced mainly by fuel burning in cars, trucks and power plants. Highest near busy roads. It inflames the airways and increases asthma attacks.
WHO 2021 guideline: 25.0 µg/m³ (24-h mean)What it isSulfur dioxide (SO₂)
A gas released by burning coal and oil in industry, refineries and ships. It irritates the eyes and airways; people with asthma are especially sensitive.
WHO 2021 guideline: 40.0 µg/m³ (24-h mean)What it isCarbon monoxide (CO)
A colourless, odourless gas from incomplete combustion — vehicle exhaust, stoves and fires. It reduces the blood's ability to carry oxygen and is dangerous in enclosed spaces.
WHO 2021 guideline: 4000 µg/m³ (24-h mean)Tap a day to see it hour by hour
Today27/09
18°13°Good38max
Today27/0918°13°
18°13°Good
38maxHour by hourAQI · PM2.5 · main
00:00377µg/m³PM2.5
01:00387µg/m³PM2.5
02:00387µg/m³PM2.5
03:00377µg/m³PM2.5
04:00366µg/m³PM2.5
05:00346µg/m³PM2.5
06:00326µg/m³PM2.5
07:00315µg/m³O₃
08:00305µg/m³O₃
09:00295µg/m³O₃
10:00294µg/m³O₃
11:00284µg/m³O₃
12:00273µg/m³O₃
13:00273µg/m³O₃
14:00263µg/m³O₃
15:00263µg/m³O₃
16:00252µg/m³O₃
17:00252µg/m³O₃
18:00252µg/m³O₃
19:00251µg/m³O₃
20:00251µg/m³O₃
21:00241µg/m³O₃
22:00241µg/m³O₃
23:00231µg/m³O₃
Worst at 01:00Best at 23:00
Tomorrow28/0919°13°Good26max
Tomorrow28/0919°13°
19°13°Good
26maxHour by hourAQI · PM2.5 · main
00:00231µg/m³O₃
01:00231µg/m³O₃
02:00231µg/m³O₃
03:00231µg/m³O₃
04:00231µg/m³O₃
05:00221µg/m³O₃
06:00211µg/m³O₃
07:00201µg/m³O₃
08:00201µg/m³O₃
09:00212µg/m³O₃
10:00231µg/m³O₃
11:00241µg/m³O₃
12:00252µg/m³O₃
13:00262µg/m³O₃
14:00262µg/m³O₃
15:00262µg/m³O₃
16:00252µg/m³O₃
17:00242µg/m³O₃
18:00222µg/m³O₃
19:00202µg/m³O₃
20:00173µg/m³O₃
21:00204µg/m³PM2.5
22:00224µg/m³PM2.5
23:00265µg/m³PM2.5
Worst at 13:00Best at 20:00
Tue29/0924°16°Moderate63max
Tue29/0924°16°
24°16°Moderate
63maxHour by hourAQI · PM2.5 · main
00:00285µg/m³PM2.5
01:00285µg/m³PM2.5
02:00265µg/m³PM2.5
03:00244µg/m³PM2.5
04:00234µg/m³PM2.5
05:00234µg/m³PM2.5
06:00244µg/m³PM2.5
07:00265µg/m³PM2.5
08:00295µg/m³PM2.5
09:00244µg/m³PM2.5
10:00234µg/m³PM2.5
11:00284µg/m³O₃
12:00324µg/m³O₃
13:00344µg/m³O₃
14:00364µg/m³O₃
15:00384µg/m³O₃
16:00394µg/m³O₃
17:00384µg/m³O₃
18:00344µg/m³O₃
19:00346µg/m³PM2.5
20:00489µg/m³PM2.5
21:005411µg/m³PM2.5
22:005813µg/m³PM2.5
23:006315µg/m³PM2.5
Worst at 23:00Best at 04:00
Wed30/0927°16°Moderate73max
Wed30/0927°16°
27°16°Moderate
73maxHour by hourAQI · PM2.5 · main
00:006517µg/m³PM2.5
01:006416µg/m³PM2.5
02:006115µg/m³PM2.5
03:006014µg/m³PM2.5
04:006014µg/m³PM2.5
05:006215µg/m³PM2.5
06:006316µg/m³PM2.5
07:006516µg/m³PM2.5
08:006718µg/m³PM2.5
09:006115µg/m³PM2.5
10:005210µg/m³PM2.5
11:00499µg/m³PM2.5
12:00438µg/m³O₃
13:00437µg/m³O₃
14:00436µg/m³O₃
15:00446µg/m³O₃
16:00456µg/m³O₃
17:00446µg/m³O₃
18:00397µg/m³O₃
19:00529µg/m³PM2.5
20:005914µg/m³PM2.5
21:006517µg/m³PM2.5
22:006919µg/m³PM2.5
23:007321µg/m³PM2.5
Worst at 23:00Best at 18:00
Index scale
US EPA · 0 to 5000–50
GoodClean air, no risk for anyone.
51–100
ModerateAcceptable; unusually sensitive people may notice mild discomfort.
101–150
Unhealthy for sensitive groupsChildren, older adults and people with heart or lung disease may have symptoms.
151–200
UnhealthyEveryone may feel effects; sensitive groups, more serious ones.
201–300
Very unhealthyHealth alert: increased risk for the whole population.
301–500
HazardousEmergency: the entire population is likely to be affected.
Index computed with the US EPA method from concentrations modelled by CAMS (Copernicus), via WeatherAPI. These are model estimates, not station measurements; for official data check your local environmental agency.
Nearby counties
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Air quality in Frederick (MD)
Air quality in Frederick (Maryland) with up-to-date data for today, tomorrow and the day after: air quality index (AQI), fine particulate matter PM2.5 and PM10, ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and carbon monoxide (CO). Find out whether the air is Good, Moderate, Unhealthy or Hazardous and make safer decisions for outdoor activities.
