With the ongoing expansion of the Longwood Medical Area, traffic in and around
Brigham Circle and Mission Hill has been increasing due to commuters, visitors,
and commercial traffic in the area. This has caused some concern over the
effects this has had on the air quality in Mission Hill, a mixed residential
and commercial neighborhood. This study aims to tie community-scale air quality
measurements to traffic measurements on Tremont Street and Huntington Avenue.
Traffic counters are set up on Huntington Ave. and Tremont St. to count traffic
and vehicle type for 24 hours a day. Levels of different air pollutants are
being measured 24 hours a day using equipment installed at the office for
the Mission Hill Health Movement. Also, area high school students will be
walking around the neighborhood on pre-scripted routes with real-time air
monitoring equipment in backpacks and GPS monitors for two 2-hour shifts each
weekday. While monitoring, these students will also be using different methods
to characterize traffic on Huntington Ave. and Tremont St.
A variety of air pollutants are being measured both at the Mission Hill Health Movement office and by the equipment carried by the students:
" Particles suspended in the air (both fine and ultrafine particles)
" Polycyclic aromatic hydrocarbons (PAHs)
" Carbon dioxide
Two other pollutants are being measured by stationary equipment at the MHHM office:
" Nitric oxide
" Black carbon
Air pollution is more than one single chemical; there are a wide variety of compounds including particles, liquids, and gases that are mixing and reacting with each other over time. There are different ways to measure and categorize the substances involved.
Two different size ranges of particles are being measured. One piece of equipment is measuring particles that are 2.5 millionths of a meter in diameter and smaller (fine particles - PM2.5), and one measures particles even smaller than that - one tenth of a millionth of a meter and smaller (ultrafine particles - PM0.1). To get an idea of the size of these particles, imagine taking a meter-stick and cutting it into a million pieces, or taking an average piece of sand and breaking it into a thousand pieces. This is the size of the particles that these instruments measure - roughly the same size as viruses and bacteria.
Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete burning of fuels, but can also be produced from burning meat or tobacco. PAHs tend to be emitted more by diesel traffic.
Nitric oxide (NO) is also produced during the burning of fuels by motor vehicles, utilities, industrial or commercial buildings, and homes. It is one type of nitrogen oxide, a group of chemicals that is highly reactive.
Black carbon is also produced by incomplete burning of fuels. It is defined
as any carbon-based pollutant that is black and is a rather wide category
of particulate air pollutants. It is a good marker for diesel traffic.
Carbon dioxide does not have immediate local health effects, but contributes to global warming and is a marker of fuel combustion.
The pollutants we are measuring tend to have higher concentrations close to busy roads. Many of these pollutants have also been linked to harmful health effects, including asthma, decreases in lung function, and other respiratory illnesses. Some PAHs may be linked with lung cancer as well.
Fine and ultrafine particles suspended in the air, including black carbon, are able to penetrate deep into the lung. Exposure to particles has been linked with coughing, lung irritation, bronchitis, and can trigger asthma attacks. These particles are also associated with heart disease.
Nitric oxide can cause respiratory problems, form particles, and react in
the presence of sunlight to form other toxic compounds, including ozone.
More info
Information in this pamphlet and further information on this topic can be found at the Environmental Protection Agency's website on air pollution: http://www.epa.gov/ebtpages/air.html
Information on respiratory diseases can be found at the American Lung Association: http://www.lungusa.org
More information about air quality in Mission Hill can be found at http://airbeat.org. This website shows air pollution measurements from a monitor in Dudley Square and includes information about specific pollutants.
If you have questions about the study, you may contact Jonathan Levy at jilevy@hsph.harvard.edu
or 617-384-8808. You may also contact Jonathan Buonocore at jbuonoco@hsph.harvard.edu