Current Air Quality Index & Pollutant Levels
Maryland, United States
Daily air quality forecast. PM2.5, PM10, O₃, NO₂, SO₂, CO.
Air Quality
61
Everyone may begin to experience health effects. Sensitive groups should avoid prolonged outdoor exertion. Keep windows closed.
μg/m³
Hourly forecast
AQI · PM2.5 μg/m³
00:006126
01:006127
02:006228
03:006329
04:006229
05:006228
06:006126
07:006025
08:005624
09:005223
10:004822
11:004421
12:004120
13:004120
14:004221
15:004421
16:004221
17:004221
18:004620
19:004718
20:004917
21:005215
22:004414
23:003714
PM2.5
25.7μg/m³
172% of WHO limitExceeded
PM10
26.6μg/m³
59% of WHO limitAcceptable
Ozone (O₃)
104.2μg/m³
104% of WHO limitExceeded
NO₂
8.6μg/m³
34% of WHO limitGood
SO₂
1.8μg/m³
4% of WHO limitGood
CO
269.4μg/m³
7% of WHO limitGood
Daily air quality forecast
Today52Moderate41–63
Wed29Fair20–44
Thu26Fair21–35
Fri27Fair22–32
Sat27Fair26–29
European AQI Scale
0–20
Good
Air pollution poses little or no risk.
21–40
Fair
Acceptable for most; very sensitive people may notice symptoms.
41–60
Moderate
Children, elderly and people with conditions should limit prolonged outdoor exertion.
61–80
Poor
Everyone may start to feel effects; sensitive groups risk more serious effects.
81–100
Very Poor
Health warning of emergency conditions; everyone is more likely to be affected.
100+
Hazardous
Health alert: serious effects for everyone — limit time outdoors.
The European Air Quality Index ranges from 0 (best) to 100+ (worst). It combines measurements of particulate matter and gas pollutants into a single number.
History — Past 30 days
min–max Avg AQI
What are these pollutants?
PM2.5 — Fine particulate matter smaller than 2.5 micrometers. These particles are small enough to bypass the nose and throat, reaching deep into the lungs and even entering the bloodstream. Major sources include vehicle exhaust, industrial processes, and wildfires.
PM10 — Coarse particles smaller than 10 micrometers, including dust, pollen, and road surface wear. While larger than PM2.5, they still cause respiratory irritation and aggravate asthma.
O₃ — Ground-level ozone is not emitted directly — it forms when nitrogen oxides and volatile organic compounds react in sunlight. Higher in summer afternoons. Can trigger asthma attacks and reduce lung function.
NO₂ — Nitrogen dioxide comes primarily from vehicle engines and power plants. It inflames the lining of the airways, making the lungs more susceptible to infection.
SO₂ — Sulfur dioxide is released by burning fossil fuels containing sulfur, especially coal and oil. Even short exposure can constrict airways, particularly in people with asthma.
CO — Carbon monoxide is an odorless gas from incomplete combustion of fuels. Outdoors, it mainly comes from vehicle traffic. At elevated levels, it reduces the blood's ability to carry oxygen.
Dust (AOD) — AOD at 550nm. Above 0.3 = Saharan dust.
Air Quality FAQ
What is the Air Quality Index?
The European AQI is a number from 0 to 100+ that summarizes how clean or polluted the air is. It combines measurements of fine particles (PM2.5, PM10) and gases (ozone, NO₂, SO₂) into a single score. The higher the number, the worse the air quality and the greater the health risk.
Who is most sensitive to air pollution?
Children, the elderly, pregnant women, and people with asthma, COPD, or heart disease are most vulnerable. Even moderate pollution levels (AQI 41–60) can trigger symptoms in these groups. Athletes and outdoor workers also face higher exposure due to increased breathing rates.
How can I protect myself?
On high-pollution days: stay indoors with windows closed, use air purifiers with HEPA filters, avoid strenuous outdoor exercise (especially near busy roads), and check the AQI forecast before planning activities. Even on moderate days, sensitive individuals should limit prolonged outdoor exertion.
When is air quality typically worst?
Ozone peaks on hot, sunny afternoons (summer). Particle pollution (PM2.5) is often worst in winter due to heating and temperature inversions that trap pollutants near the ground. Rush-hour traffic causes NO₂ spikes morning and evening. Dust events and wildfires can cause sudden, severe spikes any time of year.
Data: Copernicus CAMS · CC-BY-4.0
Air quality nearby