Nashua included in New Hampshire Code Orange particle-pollution alert

Nashua was included in a New Hampshire Code Orange Air Quality Alert for particle pollution that remained in effect until 11 p.m. EDT on July 18, 2026.

The alert was issued by the New Hampshire Department of Environmental Services and carried by the National Weather Service office in Gray. It covered a regional area that included Nashua, which was specifically named in the alert’s list of affected cities.

This was a time-limited July 18 warning, not a finding that Nashua had unhealthy air on Aug. 3. The materials reviewed for this report did not include a current Aug. 3 Nashua air-quality bulletin from the state environmental agency.

Forecast conditions and affected area

The alert covered Nashua and other communities in Eastern Hillsborough County and adjacent areas of southern New Hampshire. It concerned particle pollution and used the Code Orange classification.

An associated Nashua forecast called for patchy smoke, showers and thunderstorms, and gusty winds. Those were forecast conditions, rather than observations establishing pollution levels at a particular place or time.

A separate Nashua-area forecast cited for Aug. 3 called for a high near 86 degrees. That forecast is distinct from the July 18 air-quality alert and does not establish that the earlier pollution episode was continuing.

Advice for sensitive groups

Officials identified children, older adults, people with asthma or other lung disease, and people active outdoors as groups who could be especially affected by elevated particle pollution. They advised sensitive people to reduce strenuous or prolonged outdoor activity while the alert was in effect.

The alert did not identify a Nashua-only pollution source. It also did not report measured health impacts in Nashua or state that schools, workplaces, events, or other activities had been closed or restricted.

How the alert fits broader air-quality concerns

New Hampshire Public Radio reported in May that the state can issue Code Orange alerts for ozone and particle pollution. Its reporting said heat, humidity, transported emissions and wildfire smoke can worsen air quality in New Hampshire. That statewide context does not identify the cause of the July 18 particle-pollution alert affecting Nashua.

For residents planning outdoor work, exercise, or other sustained activity, the July alert’s practical guidance was directed at people in sensitive groups: reduce strenuous or prolonged outdoor exertion during the alert period. No further deadline or follow-up action was specified in the supplied alert materials after its 11 p.m. EDT expiration on July 18.