When it comes to air quality — both indoors and outdoors — people have a lot of questions. Understanding how air pollution affects your health, your home, and your workplace is essential for making informed decisions. This Air Quality Q&A article provides concise, expert-backed answers to the most common questions, along with authoritative government resources to help you learn more.

What Is Air Quality?

Air quality refers to how clean or polluted the air is. Good air quality means fewer harmful pollutants are present, while poor air quality indicates higher levels of contaminants that may pose health risks.

EPA

For official definitions and standards, the U.S. Environmental Protection Agency (EPA) provides detailed explanations here:
👉 https://www.epa.gov/pm-pollution/particulate-matter-pmmatter-standards

Who needs Industrial Hygiene?

What Are Common Air Pollutants?

The EPA tracks six major outdoor pollutants under the National Ambient Air Quality Standards (NAAQS):

  • Particulate Matter (PM2.5 and PM10)
  • Ground-level Ozone (O₃)
  • Carbon Monoxide (CO)
  • Sulfur Dioxide (SO₂)
  • Nitrogen Dioxide (NO₂)
  • Lead (Pb)

Each of these can affect health when concentrations are too high. More details about these pollutants and their health impacts can be found on the EPA’s Air Quality Standards page:
👉 https://www.epa.gov/criteria-air-pollutants

How Is Air Quality Measured?

Outdoor air quality is measured using air monitoring stations that track pollutant levels and report them through the Air Quality Index (AQI) — a scale from 0 to 500. The higher the AQI, the worse the air quality and the greater the health concern.

You can check current AQI levels anywhere in the U.S. via AirNow, a government-run tool:
👉 https://www.airnow.gov

What Is Considered “Good” Air Quality?

An AQI between 0 and 50 is considered “Good,” meaning air pollution poses little or no health risk.

The meaning of all AQI categories — from Good to Hazardous — is explained in this EPA overview:
👉 https://www.airnow.gov/aqi-basics

Can Indoor Air Quality Be Worse Than Outdoor Air?

Yes, indoor air quality (IAQ) can sometimes be more polluted than outdoor air, especially in poorly ventilated spaces with chemical sources (like cleaning products or building materials) or biological contaminants (like mold).

The EPA’s indoor air quality resources explain common indoor air issues and how to manage them:
👉 https://www.epa.gov/indoor-air-quality-iaq

What Are Common Indoor Air Pollutants?

Typical indoor pollutants include:

  • Volatile Organic Compounds (VOCs)
  • Formaldehyde
  • Mold and allergens
  • Carbon dioxide (CO₂)
  • Radon

For guidance on indoor air quality and health, the EPA’s IAQ page is a must-read:
👉 https://www.epa.gov/indoor-air-quality-iaq

How Does Poor Air Quality Affect Health?

Exposure to air pollution can cause:

  • Respiratory irritation (coughing, wheezing, asthma triggers)
  • Headaches and fatigue
  • Cardiovascular issues
  • Increased risk for lung diseases

Sensitive groups — including children, seniors, and people with asthma — are especially vulnerable. The EPA’s Human Health and Air Quality page explains these impacts further:
👉 https://www.epa.gov/air-quality-and-health

Is There a Government Health Standard for Indoor Air?

Unlike outdoor air, the U.S. does not have a national indoor air quality standard. Still, the EPA and CDC provide guidance on common indoor pollutants and how to reduce exposure. Reliable information on indoor air quality is available here:
👉 https://www.epa.gov/indoor-air-quality-iaq

CDC also provides guidance on indoor air exposure and health:
👉 https://www.cdc.gov/healthyhomes/indoorair.html

How Can I Improve Indoor Air Quality?

Improving IAQ depends on the source of pollution but may include:

  • Increasing ventilation
  • Regular HVAC maintenance
  • Using air purifiers with HEPA filters
  • Reducing VOC sources
  • Controlling moisture and mold

EPA’s IAQ resources include practical tips for homeowners and building managers:
👉 https://www.epa.gov/indoor-air-quality-iaq

How Can I Protect Myself on Poor Air Quality Days?

On days with unhealthy outdoor air:

Stay Informed

Reduce Exposure

  • Limit outdoor activities when AQI is high
  • Keep windows closed
  • Use air purifiers indoors

The EPA offers clear recommendations for protecting your health on poor air quality days:
👉 https://www.airnow.gov/health-advisories

What Should Businesses Do About Air Quality?

Workplaces are responsible for providing safe work environments. The Occupational Safety and Health Administration (OSHA) doesn’t set specific indoor air quality standards, but employers must ensure workplaces are free from recognized hazards and adequately ventilated. OSHA guidance on indoor air quality is available here:
👉 https://www.osha.gov/indoor-air-quality

Can Air Quality Be Tested?

Yes — both outdoor and indoor air quality can be tested. Outdoor tests are conducted by state and local air monitoring networks, while indoor air can be evaluated using professional IAQ assessments that measure particulates, VOCs, humidity, and other parameters.

Conclusion

Understanding air quality — what it is, why it matters, and how to improve it — empowers you to make healthier choices for your home, your workplace, and your community. By referencing authoritative resources like the EPA, AirNow, and OSHA, you’ll be better equipped to stay informed and protect your health against air pollution.

About Applied Environmental:

We are a Herndon, Virginia based Woman-owned, Small Business providing professional Environmental, Industrial Hygiene, Indoor Air Quality, Hazardous Material Assessments, and Abatement Air Monitoring services to both private sector and government clients since 1986. Applied Environmental provides environmental services throughout the nation. Our local clients are based in Washington, DC, Maryland, Northern Virginia including Arlington, Fairfax, Loudoun and Prince William Counties.