Haze & Visibility

When fine particles in the atmosphere scatter light, haze limits the distance people can see, and obscures the color and clarity of their view. Unlike smog, which is primarily a summertime problem, haze can occur at any time of year.

Where Does Haze Come From?

Five types of fine particles contribute to haze:

  • Sulfates
  • Nitrates
  • Organic carbon
  • Elemental carbon (soot)
  • Crustal material (soil dust, sea salt, etc.)

The importance of each type of particle varies across the U.S. and from season to season.

Major sources of the pollutants that cause haze in New England include:

  • Power plants
  • Boilers at industrial, commercial, and institutional facilities
  • Cement and lime kilns
  • Oil furnaces
  • Residential wood combustion (fireplaces, wood stoves, outdoor wood-fired boilers)

Learn more below.

Additional Resources

Why be Concerned About Haze?

Every year, more than 280 million visitors travel through 156 national park and wilderness areas. Unfortunately, many of these people are unable to enjoy the spectacular vistas they come to see. In many eastern parks, visibility has been reduced from 90 miles to between 15 and 25 miles because of regional haze from man-made air pollution.

Most of the pollution that causes regional haze is not emitted directly into the air, but forms after gases emitted from pollution sources are transformed in the atmosphere into fine particles. These can be transported great distances by the wind and have been linked to serious health problems.

Additional Resources

Is it Hazy Today?

Haze can be yellow, brown, or red-colored when there is a high concentration of nitrogen oxide pollution in the air.

A network of real-time haze cameras known as CAMNET monitors scenic urban and rural areas in the Northeast, and collects pollution and meteorological data to determine the causes of haze.

Follow the links below for current "haze cam" views of Boston.

Additional Resources

What is Government Doing About Haze?

As authorized by the federal Clean Air Act, the U.S. Environmental Protection Agency (EPA) in 1999 issued its Regional Haze Rule, requiring states and interested tribes to address haze from numerous sources - specifically as it affects visibility in 156 national parks and wilderness areas. EPA's goal is to achieve pristine natural background visibility conditions all of these public lands by 2064.

EPA created five regional planning organizations to address regional haze. Massachusetts is part of one of them - the Mid-Atlantic/Northeast Visibility Union (MANE-VU) - which also represents Connecticut, Delaware, the District of Columbia, Maine, Maryland, New Hampshire, New Jersey, New York, Pennsylvania, the Penobscot tribe, Rhode Island, the St. Regis Mohawk tribe, and Vermont, as well as federal environment, forest, park, and wildlife agencies.

Seven of the national parks and wilderness areas targeted for improvement by EPA are in the MANE-VU region.

Additional Resources

What Can You Do About Haze?

Of the steps you can take to reduce particle pollution that contributes to haze, most revolve around energy conservation and efficiency at home:

  • Be sure to insulate your home, use a programmable home heating and cooling thermostat, buy appliances, and unplug electronics and battery chargers whenever you're not using them.
  • If you buy a woodstove, look for an EPA- and MassDEP-certified unit, which is better for air quality and your family's health, and only burn seasoned wood. 
  • Keep your natural gas- or oil-fired furnace in good operating condition through regular tune-ups.

These practices will not only save you money in the long run, but also reduce particle pollution from the combustion of fuel at home and by the power plants that provide your electricity.

Additional Resources

Contact   for Haze & Visibility

Help Us Improve Mass.gov  with your feedback

Please do not include personal or contact information.