Frequently Asked Questions
Whose data is displayed on the Environmental Health Channel?
EHP conducts air quality measurements and health assessments upon request from individuals who are concerned
about their air quality and/or believe their health has been, or could be, affected by the presence of oil
and gas development near their home. All of the data displayed has been collected at the homes of residents
who have contacted EHP for environmental health monitoring.
What type of environmental data is displayed on the Environmental Health Channel?
EHP collects real-time, PM2.5 air quality measurements, both inside and outside of residences in close
proximity to unconventional oil and gas development. The Environmental Health Channel displays EHP's
analysis of PM2.5 data.
What is involved in EHP's data analysis?
Through years of PM2.5 data collection, EHP acknowledges that particle (PM2.5) exposures occur at homes
located in close proximity to unconventional oil and gas development. Also, EHP acknowledges that these
exposures are capable of leading to adverse health effects, and if examined correctly by researchers and
health professionals, they may be able to intervene to decrease these adverse health effects. To properly
identify exposures, EHP has developed a system of data analysis that observes 15-minute intervals of
real-time PM2.5 measurements. Our analysis examines several parameters of what EHP believes to constitute an
air quality exposure. These parameters include: peaks per day, peak duration, time between peaks,
accumulated particle concentration and a baseline measurement.
What does EHP define as an exposure (or "peak")?
EHP identifies a peak within datasets as any 15-minute interval of time, containing PM2.5 measurements
greater than two standard deviations above the mean value of the dataset.
How does EHP define: peaks per day, peak duration, time between peaks, accumulated particle concentration, and baseline measurements?
Peaks per day is the number of peaks within a data set occurring within 24-hours. Peak duration is the mean
of the number of minutes that all peaks lasted. Time between peaks is the mean of the number of hours when
exposures did not occur. Accumulated particle concentration is the sum of accumulated particle concentration
of peaks, within the dataset, determined by calculating the area under the curve for each exposure event.
Baseline measurement is the value which represents the baseline, or mean PM2.5 value of a home, found by
calculating the 35th percentile of a home's dataset.
Why does EHP use these components of PM2.5 monitoring at each location?
EHP is monitoring individual, personal risk for clinical health evaluation. Repeated peak exposures, even
when they are of short duration, create a pattern of chemical "doses" that are harmful to health. Physicians
can use information on "doses" of exposure along with an individual's lung volume and rate of breathing to
gain more precise indicators of exposure to air pollutants.
Is EHP's data analysis similar to the Environmental Protection Agency's (EPA) Air Quality Index (AQI)?
EHP developed its analysis program independently. Currently, the EPA has two thresholds for PM2.5 which are
considered to be health protective. The first is a 24-hour average (not to exceed 35 ug/m3) and the second
is an annual mean, averaged over 3 years (not to exceed 15 ug/m3). EHP has examined PM2.5 exposure events
and found that by averaging real-time readings into 24-hour intervals, high exposure events, harmful to
human health, lasting less than an hour are lost, or averaged out, when using such a lengthy average of
Does the Environmental Health Channel follow the same color scheme as the Environmental Protection Agency's (EPA) Air Quality Index (AQI)?
While the color scheme is similar, the AQI is very different than the Environmental Health Channel.
Therefore, the colors in the Environmental Health Channel do not represent the same air quality message as
the EPA. For example, the AQI "red" values vary between 151-200. Whereas, the Environmental Health Channel
"red" values range anywhere between 3-50, depending on which exposure parameter you're examining.
How does EHP determine when a zip code colored green becomes yellow, and so on?
We map the data of each statistic (e.g. accumulation per day) to a color spectrum. First, the data is
transformed into standard scores (z-scores), which are numbers of standard deviations (σ) away from the mean
value. Then we compute a color spectrum and map the standard scores to the spectrum, which allows users to
compare the values across zip code regions visually. Yellow colors in the middle of the spectrum indicate
that the corresponding values are closer to the mean value (from -0.3σ to 0.3σ). Green and red colors at
opposite ends of the spectrum indicate -3σ and 3σ respectively, (i.e the better and worse results).
Does the Environmental Health Channel display all of EHP's collected environmental and health data?
Not quite. Only the data which passes EHP's criteria for inclusion to the website is included. Examples of
the criteria include the followings. First, for a zip code to display air quality measurements, there must
be at least 3 environmental datasets within that zip code. Any less would be too small of a sample size to
adequately portray the mean values measured. Second, all reported health symptoms are reviewed by an EHP
health professional prior to being included into EHP's health dataset. Any health symptom existing prior to
the construction of nearby oil and gas infrastructure is not considered to be related to the existence of
new, nearby oil and gas development. Therefore, the reporting of this symptom is excluded from the
Environmental Health Channel.
Why cannot I upload my personal environmental or health data to the Environmental Health Channel?
EHP only includes health data which has been reviewed by one of our health professionals to ensure the
symptoms are not due to any other reason, such as prior exposures or existing health complications. EHP only
includes environmental data that has been analyzed.
How often is new data added to the Environmental Health Channel?
EHP receives and analyzes data intermittently, depending on current monitoring projects and/or specific
monitoring sites. Environmental data is uploaded as soon as it has been analyzed, and health data is
uploaded as soon as it has been reviewed by a health professional, meeting the criteria for inclusion.
How can I contribute my information the Environmental Health Channel?
If you would like to learn how to get involved with EHP's air monitoring program, or complete an EHP health
assessment, please contact EHP using the contact information provided.