Air Quality and Your Health: Why It Should Factor Into Where You Live

When people evaluate a neighborhood, they think about crime rates, school districts, commute times, and home prices. Almost nobody thinks about the air they'll be breathing every single day. That's a mistake — and the science is increasingly clear about just how big a mistake it is.

Air pollution is the world's largest environmental health risk, responsible for an estimated 4.2 million premature deaths globally each year according to the World Health Organization. In the United States, despite dramatic improvements since the Clean Air Act of 1970, millions of people still live in areas where the air quality fails to meet federal standards.

Where you live determines what you breathe. Here's what you need to know.

The Air Quality Index (AQI): Your Daily Air Report

The EPA's Air Quality Index is the standard measure of air pollution in the United States. It translates complex pollutant concentration data into a simple 0–500 scale:

• 0–50 (Good): Air quality is satisfactory with little or no risk. Green.
• 51–100 (Moderate): Acceptable, but some pollutants may be a concern for a very small number of people who are unusually sensitive. Yellow.
• 101–150 (Unhealthy for Sensitive Groups): Members of sensitive groups (children, elderly, people with respiratory conditions) may experience health effects. Orange.
• 151–200 (Unhealthy): Everyone may begin to experience health effects; sensitive groups may experience more serious effects. Red.
• 201–300 (Very Unhealthy): Health alert — everyone may experience more serious health effects. Purple.
• 301–500 (Hazardous): Emergency conditions. The entire population is likely to be affected. Maroon.

The AQI is calculated for five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. The highest individual pollutant score becomes the overall AQI for that day.

The Pollutants That Matter Most

PM2.5 (Fine Particulate Matter)

PM2.5 refers to particles smaller than 2.5 micrometers — about 30 times smaller than a human hair. These particles are so small they can penetrate deep into your lungs and even enter your bloodstream.

Sources include vehicle exhaust, power plants, industrial processes, wildfires, and residential wood burning. PM2.5 is arguably the most dangerous common air pollutant because of its ability to bypass your body's natural defenses.

Health effects of long-term PM2.5 exposure:

• Increased risk of heart disease and stroke
• Reduced lung function and development of chronic respiratory disease
• Increased risk of lung cancer
• Premature death from cardiovascular and respiratory causes
• Worsening of asthma and allergies

A landmark Harvard study found that for every 10 μg/m³ increase in long-term PM2.5 exposure, the risk of death from all causes increased by 7.3%. That's a meaningful number for a factor most people never consider when choosing where to live.

Ground-Level Ozone

Ozone in the upper atmosphere protects us from UV radiation. Ozone at ground level is a harmful pollutant formed when nitrogen oxides and volatile organic compounds react in sunlight. It's the primary component of smog.

Ground-level ozone is worst on hot, sunny days in urban areas — exactly when people want to be outside. It irritates the respiratory system, reduces lung function, aggravates asthma, and increases susceptibility to respiratory infections.

Nitrogen Dioxide (NO2)

Primarily from vehicle emissions and power plants, NO2 irritates airways and increases susceptibility to respiratory infections. People living near major highways or in dense urban cores are disproportionately exposed.

Who's Most Vulnerable?

Air pollution doesn't affect everyone equally:

• Children: Their lungs are still developing, they breathe faster than adults, and they spend more time outdoors. Research shows that children who grow up in high-pollution areas have measurably reduced lung function as adults.
• Elderly: Age-related decline in lung function makes older adults more susceptible to pollution's effects.
• People with asthma or COPD: Pollution triggers flare-ups and can accelerate disease progression.
• Pregnant women: Exposure to high PM2.5 during pregnancy is linked to low birth weight and preterm delivery.
• Outdoor workers: Construction workers, landscapers, delivery drivers, and others who work outside face higher cumulative exposure.

If you or your family members fall into any of these categories, air quality should be weighted heavily in your housing decision.

The Geography of Air Quality

Air quality varies enormously across the United States, and the patterns aren't always intuitive:

Worst Air Quality Regions

• Central Valley, California: Bakersfield, Fresno, and Visalia consistently rank among the most polluted cities in America. Agricultural emissions, vehicle traffic, and a valley geography that traps pollution create a persistent problem.
• Los Angeles Basin: Despite decades of improvement, LA still has some of the worst ozone pollution in the country.
• Industrial Midwest: Parts of Ohio, Pennsylvania, and Indiana near heavy industry and coal plants.
• Wildfire-affected areas: Increasingly, the western US experiences severe seasonal air quality episodes from wildfires. What was once a few days a year can now stretch to weeks.

Best Air Quality Regions

• Northern Great Plains: Montana, Wyoming, North Dakota — low population density and minimal industrial activity.
• Northern New England: Vermont, Maine, New Hampshire — forested, low-density, upwind of major industrial centers.
• Hawaii: Isolated in the Pacific with steady trade winds (except near volcanic activity on the Big Island).
• Pacific Northwest (historically): Seattle and Portland traditionally had excellent air quality, though wildfire smoke has increasingly impacted summer months.

Hyperlocal Variation

Even within a single city, air quality can vary significantly:

• Homes near major highways have measurably higher NO2 and PM2.5 levels
• Proximity to industrial facilities matters
• Elevation and prevailing wind patterns create microclimates
• Urban tree canopy can moderate local pollution levels

A study published in Environmental Health Perspectives found that PM2.5 concentrations can vary by 8x within a single urban area. Your specific address matters, not just your city.

How to Check Air Quality Before You Buy

Check AirNow.gov

The EPA's AirNow website provides current and forecast AQI data by zip code. Check it over several weeks to get a sense of typical conditions, not just a single day.

Look at Annual Averages

Daily AQI fluctuates. What matters for long-term health is the annual average. The EPA's AQS (Air Quality System) database has annual summary statistics for monitoring stations across the country.

Consider Seasonal Patterns

Some areas have good air quality most of the year but terrible conditions during certain seasons (wildfire season in the West, ozone season in summer, inversion season in winter in mountain valleys).

Check Proximity to Pollution Sources

How close is the home to major highways, industrial facilities, power plants, or agricultural operations? Even if the city-wide AQI is good, hyperlocal conditions near pollution sources can be poor.

Get a StreetScore Report

StreetScore includes air quality data in every neighborhood report. We map your address to the nearest EPA monitoring stations and assess both current conditions and long-term trends. It's one piece of a comprehensive report that also covers crime, flood risk, walkability, schools, and more — because air quality doesn't exist in isolation from other neighborhood factors.

The Financial Angle

Air quality isn't just a health issue — it's a financial one:

• Healthcare costs: People in high-pollution areas have higher rates of respiratory illness, cardiovascular disease, and associated medical expenses
• Property values: Research from UC Berkeley found that a 10% reduction in PM2.5 increases home values by approximately 0.3-0.5%
• Energy costs: Areas with poor air quality often mean more time running air purifiers and keeping windows closed, increasing energy bills
• Insurance: Some health insurance plans factor geographic risk into premiums

The Bottom Line

You're going to breathe the air at your home address roughly 15,000 times per day for as long as you live there. Over the course of a 30-year mortgage, that's over 160 million breaths. The cumulative health impact of those breaths depends enormously on where you choose to live.

Air quality should be a first-tier consideration when choosing a neighborhood, right alongside safety, schools, and affordability. The data to make informed decisions exists — you just have to look at it.

Check the air quality at any US address with a free StreetScore neighborhood report. Because the air you breathe every day matters more than the countertops in your kitchen.