🌿 CleanAirData
← Back to all cities

Waltham, MA

🌍
Looking for air quality outside the US? We currently only cover US cities. For international data, please check your local environmental agency website.

Long-term air quality

What this page tells you

This page combines annual PM2.5, unhealthy days, 5-year trend, and data coverage so you can compare long-term air quality, not just today's reading.

Jump to indoor air guidance Read the formula
⚠️
Note: Waltham does not have its own EPA monitor and this page relies on the nearest monitor in Boston, 9.1 miles away.
📍 Homebuyer Guide 📊 Data Coverage: 100% 📅 2021-2025 Trends

Waltham, MA air quality summary: Waltham, MA, maintains a clean air score of 83.4 and a grade of B. The city has an annual PM2.5 mean of 6, reflecting its long-term environmental status. Waltham records a PM2.5 annual mean of 6, which is considered a moderate level for long-term exposure. The long-term air quality in Waltham has been improving over recent years.

Clean Air Score

83
Grade B

The clean air score of 83.4 and grade of B indicate a moderate and consistent air quality profile over the long term. These values suggest that the area generally meets established standards for fine particulate matter.

🏡 What This Means for Buying

Air quality should be treated as one factor in a broader relocation or housing decision in Waltham. The data provides a historical baseline for evaluating the local atmosphere over several years.

Best time for outdoor visits: Check seasonal chart

Indoor Air Quality in Waltham, MA

Outdoor pollution can still affect indoor air when windows are open, filtration is weak, or wildfire smoke moves in.

How to react when today's AQI changes

Use the AQI bands below to decide whether to open windows, run an air purifier, or stay indoors when pollution spikes in Waltham.

AQI 0-50

Good

Open windows: Open windows if you want fresh air.

Air purifier: No purifier needed for most homes.

Indoor activity: Normal indoor activity is fine.

AQI 51-100

Moderate

Open windows: Sensitive groups should limit open-window time.

Air purifier: Use fans or filtration if dust or pollen is bothering you.

Indoor activity: Most people can stay active indoors.

AQI 101-150

Unhealthy for Sensitive Groups

Open windows: Keep windows closed.

Air purifier: Run a HEPA purifier in the main room and bedroom.

Indoor activity: Sensitive groups should reduce outdoor exposure.

AQI 151+

Unhealthy

Open windows: Keep windows and doors closed.

Air purifier: Run HEPA continuously and seal obvious drafts.

Indoor activity: Stay indoors as much as possible; use an N95 if you must go out.

Common indoor air concerns in Waltham:

  • Seasonal pollen and dust mite allergens
  • VOCs from household products

Recommended action: If today's AQI reaches 101 or higher, close windows and run HEPA filtration before indoor air starts to feel smoky or stale.

Top Products for Waltham Homes:

Best HEPA Air Purifier for Waltham Wildfire Smoke PM2.5 Indoor Air Quality Monitor Formaldehyde & VOC Detector
People also search: "indoor air quality in Waltham, MA"

🩺 My Health Risk Assessment

See how Waltham's air quality affects you and your family specifically.

Current Risk Level
Low Risk
🟢
💡

Health Advice

Enjoy the outdoors! Air quality is great.

Est. Annual "Risky Days" for you: ~0 days/year

Add Waltham Air Quality to your site

Perfect for local news, real estate blogs, and community pages.

</> Create Free Widget

🏡 Property Value Impact Analysis

Estimated Impact (5-Year)
Positive Signal
+4.8% theoretical value retention

Between 2019 and 2024, Waltham's air quality improved by 1.2 μg/m³. Based on NBER studies, this change correlates with a estimated 4.8% increase in relative property value retention.

* Methodology: Comparison based on National Bureau of Economic Research (NBER) Working Paper 15655 correlation between PM2.5 reduction and housing prices. This is a theoretical estimate for informational purposes only.
Sponsor
Annual PM2.5
6 μg/m³
WHO Target: <5.0
Good Days
100.0 %
% days AQI < 100
5-Year Trend
Improving
↑ Improving
Long-term direction
Extreme Days
0 days/yr
Days AQI > 150 (Est.)

Why Waltham earned a 83.4

Raw inputs, scoring weights, and data coverage for this city.

See full formula
Annual Air Quality
6 μg/m³
Component score 85.5 × 40% = 34.2 points
Unhealthy Days
0 days/yr est.
0% of days above AQI 100. Component score 100 × 25% = 25.0 points
5-Year Trend
Improving
Component score 56 × 20% = 11.2 points
Seasonal Variability
91.7
Higher means steadier month-to-month air. Weighted contribution: 9.2 points
Extreme Events
100
Captures severe pollution spikes. Weighted contribution: 5.0 points
Coverage & Monitoring
100%
Proxy monitor: Boston (9.1 miles away)
🏃

Best Time to Run

Find the cleanest hours for your run today.
🚴

Cycling Forecast

Avoid pollution spikes on your next ride.

📅 Past 30 Days Trend

Real-time daily PM2.5 AQI

Live Data

Score Breakdown

Component Weight Score Contribution
Annual Air Quality 40% 85.5
Unhealthy Days 25% 100
5-Year Trend 20% 56
Seasonal Variability 10% 91.7
Extreme Events 5% 100

Explore More Air Quality Data

View more cities in MA See how Waltham compares nationally

Frequently Asked Questions

How often is this air quality data updated? Our historical trend models and annual rankings are updated regularly based on official EPA data to ensure reports reflect the latest available long-term trends.
What sources does CleanAirData use? We rely strictly on official U.S. Environmental Protection Agency (EPA) monitoring station data for all historical air quality scoring and reports.
Data sourced from U.S. Environmental Protection Agency (EPA) — See our methodology

About This Data

Data Sources

Historical air quality mapping and scoring are based completely on official U.S. Environmental Protection Agency (EPA) AirNow API data. 5-day AQI forecasts are provided by WAQI.

Methodology

Our Clean Air Score (0-100) is a proprietary algorithm that weighs multiple factors:

  • Annual PM2.5 averages (40%)
  • Frequency of unhealthy days (25%)
  • 5-year pollution trends (20%)
  • Seasonal variability and extreme events (15%)

Updates & Accuracy

Real-time data is updated hourly. Historical aggregate scores are recalculated monthly to reflect the latest trends. While we strive for accuracy, sensor maintenance and local conditions can affect individual readings.

Practical Advice

When AQI > 100: Sensitive groups (children, elderly, asthmatics) should limit prolonged outdoor exertion.
When AQI > 150: Everyone should avoid outdoor exercise and keep windows closed.

Data provided for informational purposes only. Always consult local health officials during extreme smoke or pollution events.

More Cities in MA

Chicopee Grade A
Score: 89.3/100
North Chicopee Grade A
Score: 89.3/100
Westfield Grade A
Score: 89.3/100
Holyoke Grade A
Score: 89.3/100
Amherst Grade A
Score: 89.3/100
Northampton Grade A
Score: 89.3/100

Similar Rankings Nationwide

#442 Newton, MA
Score: 83.4/100
#443 Somerville, MA
Score: 83.4/100
#444 Framingham, MA
Score: 83.4/100
#445 Brookline, MA
Score: 83.4/100
#446 Arlington, MA
Score: 83.4/100
#447 Jamaica Plain, MA
Score: 83.4/100

Waltham Air Quality FAQs

Is Waltham a good fit for people who care about long-term air quality?

Waltham has a clean air score of 83.4 and a grade of B, with an annual PM2.5 mean of 6. These figures indicate a moderate and improving long-term air quality environment.

What is the frequency of unhealthy air or long-term pollution exposure in Waltham?

Waltham has recorded 0 percent of unhealthy air days, supporting its grade of B. Long-term exposure is defined by the steady annual PM2.5 mean of 6.

Is air quality in Waltham improving or getting worse over time?

Long-term air quality in Waltham has been improving over recent years. This trend is documented by data with 100 percent completeness.

Does air quality vary within different parts of Waltham?

Air quality can vary within the city due to local traffic, industry, and location patterns. Localized conditions may lead to different particulate levels in specific districts.