AIR QUALITY MA

Air Quality in Marshfield, MA: Good (45 AQI)

AQI 45 · Good · Ozone · Updated 2026-05-03

Marshfield's air quality is good. Air pollution poses little or no risk.

Data: EPA AirNow, FEMA National Risk Index Last verified: 2026-05-03

Average AQI

Good

AQI Category

Wildfire Risk

Mold Score

ZIP Codes

What is AQI?

The Air Quality Index (AQI) is a standardized scale from 0 to 500 that measures air pollution levels. 0-50 is "Good," 51-100 is "Moderate," 101-150 is "Unhealthy for Sensitive Groups," and above 150 is "Unhealthy" for everyone. AQI tracks five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Marshfield's average AQI of 45 falls in the "Good" range.

Air Quality by ZIP Code in Marshfield

AQI varies across Marshfield's 1 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
02050	45	Good	20	66	View report →

Air Quality Overview

Marshfield, Massachusetts has good air quality with an average AQI of 45. This means air pollution poses little or no risk. The dominant pollutant measured is Ozone.

The Air Quality Index (AQI) is an EPA-standardized scale from 0 to 500. Values below 50 are "Good," 51-100 "Moderate," 101-150 "Unhealthy for Sensitive Groups," 151-200 "Unhealthy," 201-300 "Very Unhealthy," and above 300 "Hazardous."

Dominant Pollutant: Ozone

Ground-level ozone forms when pollutants from cars, power plants, and industrial facilities react with sunlight. Unlike stratospheric ozone, ground-level ozone is harmful to breathe.

Health effects of ozone exposure:

Irritation of the respiratory system
Reduced lung function
Aggravation of asthma and chronic lung diseases
Increased susceptibility to respiratory infections

Peak times: Ozone levels are typically highest on hot, sunny afternoons. Exercise outdoors in the morning when levels are lower.

Air Quality by ZIP Code in Marshfield

AQI varies across Marshfield's 1 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

ZIP Code	AQI	Category	Wildfire Risk	Mold Score
02050	45	Good	20	66

Wildfire Smoke Risk

Marshfield has an elevated wildfire smoke risk with an average smoke risk score of 20 (scale 0-100). There have been 2 fires recorded within 100 km of city ZIP codes.

Metric	Value
Avg. smoke risk score	20
Max smoke risk score	20
Fires within 100 km	2
High-risk ZIP codes	0

Wildfire smoke contains PM2.5, carbon monoxide, and volatile organic compounds. Even short-term exposure can trigger asthma attacks and respiratory distress.

Indoor Mold Risk

Marshfield has an average mold risk score of 66 out of 100, with 1 ZIP codes in the high-risk category.

Factor	Value
Mold risk score	66/100
Average humidity	67% RH
High-risk ZIPs	1
Peak season	summer high

Mold risk is influenced by humidity levels, housing age (older homes have more moisture issues), flood history, and water infrastructure quality. Indoor humidity above 60% creates favorable conditions for mold growth.

Signs of mold problems: musty odors, visible growth on walls or ceilings, worsening allergies indoors, condensation on windows. Professional mold testing ($300-$600) can identify hidden issues.

Health Recommendations

With good air quality (AQI 45), Marshfield residents can enjoy outdoor activities without significant restrictions. General tips:

Monitor AQI during wildfire season for temporary spikes
Use HEPA air purifiers indoors if you have respiratory conditions
Maintain indoor humidity between 30-50% to prevent mold

Marshfield vs. Nearby Massachusetts Cities

How Marshfield's air quality compares to nearby cities:

City	AQI	Category	Population
Marshfield	45	Good	34,000
Brant Rock	40	Good	34,000
Green Harbor	40	Good	34,000
Humarock	40	Good	34,000

ZIP Codes in Marshfield

Marshfield covers 1 ZIP code. Air quality can vary by neighborhood based on proximity to highways, industrial areas, and green spaces. Check your specific ZIP code for localized data.

Data Sources

Air quality: EPA AirNow — real-time and historical AQI data
Wildfire risk: FEMA National Risk Index
Mold risk: Derived from EPA, FEMA, Census ACS (humidity, housing age, flood history)
Monthly AQI: EPA Air Quality Statistics

Updated daily.

Frequently Asked Questions

Is the air safe to breathe in Marshfield?

Yes — Marshfield's average AQI is 45 (Good). Air pollution poses little or no risk for the general population.

How many unhealthy air days does Marshfield have?

Marshfield has zero recorded unhealthy air quality days, which is excellent. Air quality can still vary seasonally due to wildfire smoke, pollen, or industrial activity.

What is the AQI in Marshfield?

The average Air Quality Index (AQI) in Marshfield is 45, categorized as Good. The primary pollutant is Ozone. AQI ranges from 0-500, where 0-50 is Good, 51-100 Moderate, 101-150 Unhealthy for Sensitive Groups, and 151+ Unhealthy.

What is the wildfire risk in Marshfield?

Marshfield has a wildfire risk score of 20 out of 100. Low wildfire risk means smoke events are uncommon, but regional fires can still temporarily affect air quality.

Is mold a concern in Marshfield?

Marshfield has a mold risk score of 66 out of 100, based on humidity, precipitation, and temperature data. This is elevated — proper ventilation, dehumidifiers, and regular inspection of basements and bathrooms are important.

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