Outdoor air quality refers to the condition of air outdoors. It focuses on pollutants that impact human health. Outdoor air pollution results from human activities like burning fossil fuels. Pollution can also come from natural sources like smoke and dust. Poor outdoor air quality can cause both short- and long-term harm to our airways and lungs, as well as impact other important organs in our bodies.
What causes poor outdoor air quality?
Primary sources of human-made air pollution include:
- Emissions from cars and trucks
- Manufacturing and power plants
- Homes and businesses
- Fumes from fuel and chemical manufacturing
Smoke from wildfires and blowing dust during times of drought can also result in poor air quality.
Local emissions, such as traffic-related air pollutants and burning oil and gas for home heating, contribute to poor local air quality. Air pollution may also blow in from other regions of the US and Canada.
Extreme heat events in Massachusetts can result in high concentrations of ozone, pollen, and particles in the air like dust, dirt, smoke, or liquid droplets (particulate matter) that are so small they can be inhaled and cause serious health problems.
How is outdoor air quality a public health concern?
Studies associate short and long-term exposure to poor outdoor air quality with:
- Heart disease and cardiac problems
- Stroke
- Reduced lung function, lung disease, and lung cancer
- Asthma
- Diabetes
- Reduced life expectancy
- Emergency department visits and hospitalizations
Chronic exposure can also interfere with proper lung growth and development in children.
Why is MA EPHT tracking outdoor air quality?
Outdoor air quality monitoring gives us data on the concentration of pollutants. This data is the best available information at a given time and location. However, not all locations have monitors.
Modeled air quality data exists for particulate matter and ozone. The EPA and CDC uses the Downscaler Model for this data. The Downscaler Model combines the EPA's Air Quality System (AQS) measurements with predictions from the Community Multi-Scale Air Quality Model (CMAQ).
These data fill in the substantial time and geography gaps that exist in the monitored data. In counties with monitors, the combined “monitored and modeled” pollutant dataset is useful. It helps us understand pollution trends that may occur at the local and community levels.
Both monitored and modeled data provide historical information on air quality. This can show us the frequency of poor air quality events.
What outdoor air quality hazards are expected in Massachusetts?
The federal Clean Air Act requires the U.S. Environmental Protection Agency (U.S. EPA) to set limits on air pollutants to protect public health, including the health of "sensitive" populations. These national standards set limits for six air pollutants across the United States:
- Carbon Monoxide (CO)
- Lead (Pb)
- Nitrogen Dioxide (NO2)
- Sulfur Dioxide (SO2)
- Ozone (O3), and
- Particulate Matter (e.g., PM10 and PM2.5).
In Massachusetts, particulate matter and ozone are the most commonly monitored outdoor air pollutants. These mostly result from fossil fuel combustion for transportation, heating, and power generation. Particulate matter may reach extreme levels during wildfire smoke events and summertime heat waves. Ozone levels may become dangerous on hot days and days when pollutants are “trapped” at ground level by the weather.
Poor outdoor air quality in Massachusetts may involve local exposure to any of several hundred additional toxic chemicals. For example, benzene or other industrial solvents. MassDEP maintains an updated list of these regulated chemicals.
How are people exposed to poor outdoor air quality?
Outdoor air quality affects the air we breathe both outdoors and indoors. People are most heavily exposed to outdoor air pollution during outdoor activities. These activities include working, driving, commuting, and exercising. Poor outdoor air quality may also affect indoor air quality. Polluted air can come in through open windows. It can also filter through walls or be blown in by an unfiltered ventilation systems.
Who is most at risk from poor outdoor air quality?
Some people may be more at risk of health problems due to poor air quality because of where they live, their ability to find and understand official government information, their ability to prepare and respond, and if they already have health problems. These people include:
- Children under 5 and people over 65
- Pregnant people
- People with disabilities
- People with medical conditions such as heart disease, asthma, lung disease and respiratory allergies
- People of color due to systemic racism (e.g., pollution near major highways and/or industrial areas in neighborhoods)
- People who speak little or no English, and who may not receive emergency messages in their native language
- People that live in areas with heavy traffic
- People that work or exercise outdoors
How can you protect your health from outdoor air pollution?
Illness and death due to poor air quality can be prevented. Here are some tips for protecting health from poor air quality:
- Be aware of the air quality around you - check your community’s Air Quality Index
- Reduce common asthma triggers at home, such as secondhand smoke, dust, pet hair and dander, and mold
- Use portable air filters or air conditioning if you have it
- Use high-efficiency (HEPA) air filters in heating and cooling systems
- Close windows and vents in homes and vehicles during air quality alerts and wildfire smoke events
- Maintain humidity levels between 30-50% indoors with air conditioners, fans, or dehumidifiers
- Ask your doctor about how to recognize seasonal allergy symptoms and reactions to air pollution and wildfire smoke and how to use appropriate medications
- Limit time outside on days with poor air quality or high pollen counts
- Ask schools and camps to reduce children’s exposure to common asthma triggers such as exposure to idling vehicles in pick-up and drop-off lines
- Walk or bike or take public transportation when possible
- When using a car, do not idle your vehicle for any longer than necessary
- Plan to move outdoor activities indoors during wildfire smoke events
- Learn how to create a clean air room in your home using a box fan
To learn more, visit the National Institutes of Environmental Health Science’s Air Pollution and Your Health webpage. You can also visit the CDC’s About Air Quality and How Wildfire Smoke Affects Your Body webpages. The Massachusetts DPH also offers factsheets for Poor Outdoor Air Quality and Wildfire Smoke Events which are available in 16 languages.
Where can I find additional information on outdoor air quality?
In Massachusetts, the MassDEP Air Assessment Branch (AAB) operates an ambient air quality monitoring network. It has 22 monitoring stations located in 17 cities and towns in Massachusetts. The Wampanoag Tribe of Gay Head operates an ozone monitoring site on Martha’s Vineyard. Monitoring sites are chosen to meet U.S. EPA’s national monitoring criteria.
For example, some sites are selected because they are probable “hot spots” for high levels of certain air pollutants. Others are chosen to provide data that are representative of a wider area. The MassDEP provides a map of the “Air Quality Index” (AQI). The map tells you how clean or polluted your air is and what associated health effects might be a concern. (For more information, connect to: MassDEP Air Quality Online).
MassDEP submits monitoring data to a U.S. EPA database system called the Air Quality System (AQS). This system is accessible to the public. The outdoor air quality measures for MA EPHT are based on monitoring data from the U.S. EPA's AQS.
Additionally, MassDEP has around 200 small area monitors for PM2.5 and Ozone in rural areas and environmental justice areas. Current readings for these monitors may be viewed on AirNow’s Fire and Smoke Map. Other personal and community-owned small area monitors on Purple Air
Available data
Use the Explore Outdoor Air Quality Data on this page to access the following measures for outdoor air quality for your community:
- Monitored Ozone (O3), and Particulate Matter (PM2.5) – county only
- Modeled Ozone (O3), and Particulate Matter (PM2.5) – county, community, census tract
- Combined monitored and modeled Ozone (O3), and Particulate Matter (PM2.5) – county only
The most current available data will be shown. Be sure to check the site periodically as new data are added each year.
Related links
Additional resources
Massachusetts
- Massachusetts Department of Environmental Protection (MassDEP): Air quality information for Massachusetts
- MassDEP Air Quality On-line: Current air quality data and information for Massachusetts at the Massachusetts Department of Environmental Protection (MassDEP)
- Air Pollutants in Massachusetts: Toxics, lead, haze, acid rain, and other air pollutants monitored by MassDEP
- Criteria Air Pollutants: Learn about six common air pollutants that are found everywhere and emitted from a range of sources: homes, motor vehicles, industry, power plants, and more.
- View Annual Air Quality Reports from MassDEP Federal Standards
National
- National Environmental Public Health Tracking: To view the National Environmental Public Health Tracking website
- U.S. EPA Integrated Compliance Information System (ICIS) for Air: Contains data regarding regulated Clean Air Act stationary sources and their compliance records
- AirNow site with national air quality information: Air quality forecasts for the United States
- U.S. EPA Air Compare: Local air quality information
- U.S. EPA Air Trends: Air quality trends for the criteria air pollutants
- U.S. EPA Ambient Monitoring and Technology Information Center: Information on ambient air quality monitoring programs
- U.S. EPA Clean Air Act: Information on the Clean Air Act
- U.S. EPA National Air Quality and Emissions Trends Report: Current emissions trends data
- U.S. EPA Office of Air and Radiation: Information on the Office of Air and Radiation and regulations for controlling air pollution and radiation exposure
- U.S. EPA Report on the Environment: Report on status of and trends in the quality of the nation’s environment, including air
- U.S. EPA Tribal Air Quality: Information from the tribal air program at U.S. EPA
- U.S. EPA Urban Strategy: Framework for addressing air toxics emissions in urban areas
