Worst air pollution Portsmouth, today and tomorrow
Today (16 July): Air quality in Portsmouth is fair. AQI, NO2, and O3 are fair; PM2.5, PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 11:00 AM (O3: 33.2/100).
Tomorrow (17 July 2026): Air quality in Portsmouth is fair. NO2 decreases to good; all other pollutants stay as today. Pollution peaks around 8:00 AM (O3: 27.6/100). Airmine updates local air quality forecasts four times daily.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Portsmouth's air quality in New Hampshire benefits from the Great Bay estuary and Atlantic coastal position, with consistent maritime breezes providing reliable ventilation along the New England seacoast. Vehicle emissions from I-95 and the Pease Tradeport's aviation operations are the primary local sources, while the coastal position and consistent Atlantic airflows generally maintain Portsmouth among New England's cleaner coastal urban environments throughout the year.
Today - 16 July | Pollution peaks at 11:00
AQI:
Fair
33.2/100
PM2.5 (fine particles):
Good
8.9/100
PM10 (coarse particles):
Good
5.1/100
NO2 (nitrogen dioxide):
Fair
21.5/100
O3 (ozone):
Fair
33.2/100
SO2 (sulfur dioxide):
Good
1.3/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
5.8/100
PM1 (ultrafine particles):
Good
6.2/100
Levels show the poorest local air quality during the day
Tomorrow - 17 July | Pollution peaks at 08:00
AQI:
Fair
27.6/100
PM2.5 (fine particles):
Good
5.7/100
PM10 (coarse particles):
Good
2.3/100
NO2 (nitrogen dioxide):
Good
15.7/100
O3 (ozone):
Fair
27.6/100
SO2 (sulfur dioxide):
Good
1.4/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
2.9/100
PM1 (ultrafine particles):
Good
4.1/100
Pollen forecast in Portsmouth
View pollen forecastAir quality forecasts for neighbourhoods and landmarks in Portsmouth
Frequently Asked Questions
Is air quality bad in Portsmouth right now?
On 16 July 2026, overall air quality in Portsmouth is fair. AQI is the main air quality indicator at 33.2/100. Pollution peaks around 11:00 AM (O3: 33.2/100).
Will air quality be worse tomorrow in Portsmouth?
On 17 July 2026, air quality conditions in Portsmouth will be similar to today, with AQI forecast at fair at 27.6/100. Pollution peaks around 8:00 AM (O3: 27.6/100).
When is air pollution at its worst in Portsmouth?
Like most US cities, Portsmouth sees air quality shift from season to season. Typically, the shoulder seasons bring the most consistently clean air of the year, while hot, humid summer days bring the highest ozone risk, often worsened by pollution transported in from other regions. Winter cold fronts tend to clear the air quickly, so extended pollution episodes are relatively uncommon.
Are air quality levels in Portsmouth based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Want to see air quality forecasts for other cities in United States?
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Data provided by Airmine — Last update: 16 July 2026 at 10:33 CEST (Data is updated four times daily.)
This forecast is produced independently using Airmine's own atmospheric data and models.
Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
For long term forecasts and maps, see the Airmine app