Current Air Quality Index & Pollutant Levels
Maryland, United States
Daily air quality forecast. PM2.5, PM10, O₃, NO₂, SO₂, CO.
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37
Air quality is acceptable. Unusually sensitive individuals should consider limiting prolonged outdoor exertion.
μg/m³
Hourly forecast
AQI · PM2.5 μg/m³
03:003710
04:003610
05:003610
06:003511
07:003411
08:003413
09:004113
10:005312
11:006111
12:00619
13:00618
14:00628
15:00618
16:00617
17:00627
18:00607
19:00597
20:005510
21:005116
22:005023
23:004420
00:004114
01:003912
02:003811
PM2.5
10.2μg/m³
68% of WHO limitAcceptable
PM10
11.0μg/m³
24% of WHO limitGood
Ozone (O₃)
92.7μg/m³
93% of WHO limitConcerning
NO₂
6.1μg/m³
24% of WHO limitGood
SO₂
1.6μg/m³
4% of WHO limitGood
CO
179.5μg/m³
4% of WHO limitGood
Dust (AOD)
0.01AOD
Clean
Daily air quality forecast
Today50Moderate34–62
Fri49Moderate31–66
Sat42Moderate26–60
Sun42Moderate35–50
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–maxAvg 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
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