81
particulate-matter-pm-basics; accessed 10/2/2019). There are respiratory concerns
with these materials.
Substances that are small enough to be inhaled by the human respiratory system
make up the PM that people worry about. These are generally divided into two size
classes: PM 10 consists of particulates with diameters of 10 micrometers or less, and
PM 2.5 consists of even smaller particles with diameters equal to or less than 2 ½
micrometers. Broadly speaking, PM 10 is dust, and PM 2.5 is smoke. The smaller the
particle, the deeper it can travel into the lungs.
Much of this material is fairly benign – after all, people breathe in household
dust all the time with no ill effects other than a sneeze, and wood smoke from a
campfire causes watery eyes and barbecue-scented clothes but creates little permanent damage. However, some of the dust and smoke on industrial sites like a well
pad can pose significant risks to human health. Frack sand, for example, typically
consists of crystalline silica (SiO 2 ) in the form of quartz. Inhaling quantities of PM 10
quartz dust can lead to silicosis, an emphysema-like illness resulting from the scarring of lung tissue by the sharp particles. A more intense form of the disease from
acute dust exposure can even cause the alveoli of the lungs to be filled with dust
particles and permanently blocked (source: U.S. Centers for Disease Control [CDC]
websites).
In addition to quartz, silica can occur in four other different crystal structures
known as polymorphs: coesite and stishovite, which are fairly rare, and tridymite
and cristobalite, which are more common. Tridymite and cristobalite are hightemperature, low-pressure polymorphs of silica that typically occur in volcanic
rocks, but they can also form in lower temperature environments through processes
like the devitrification of silica-rich glass (Jones and Segnit 1972). Cristobalite is
particularly dangerous to inhale – it forms needle-like crystals similar to asbestos
that can penetrate and damage lung tissue. There is also evidence that cristobalite is
a potent carcinogen, and some studies indicate that other minerals fused to the edge
of cristobalite crystals can make the material even more toxic (Horwell et al. 2012).
The most common finer particulate matter (PM 2.5 ) encountered during drilling
and fracking is black smoke from diesel exhaust. Diesel emissions consist of vaporphase exhaust gases and diesel particulate matter or DPM. DPM is made up of PM 2.5
soot particles with a solid core of elemental carbon, surrounded by other chemical
substances attached to the carbon surface, including metals, sulfates, silicates and
aromatic hydrocarbons. Short term exposure to high concentrations of exhaust or
DPM can result in headaches, dizziness, and irritation of the eye, nose and throat. In
June 2012 the International Agency for Cancer Research (IARC) classified diesel
exhaust and DPM as known human carcinogens. Prolonged exposure can increase
the risk of cardiovascular, cardiopulmonary and respiratory disease, and lung cancer
(https://www.osha.gov/dts/hazardalerts/diesel_exhaust_hazard_alert.html;
accessed 10/3/2019).
The hazards posed by particulate matter emitted during drilling and fracking
operations on shale gas or tight oil well sites are similar in nature and intensity
compared to those from other construction sites. Oil and gas wells are basically
short-term construction projects and while they do emit dust and smoke during their
5.1 Particulate Matter
particulate-matter-pm-basics; accessed 10/2/2019). There are respiratory concerns
with these materials.
Substances that are small enough to be inhaled by the human respiratory system
make up the PM that people worry about. These are generally divided into two size
classes: PM 10 consists of particulates with diameters of 10 micrometers or less, and
PM 2.5 consists of even smaller particles with diameters equal to or less than 2 ½
micrometers. Broadly speaking, PM 10 is dust, and PM 2.5 is smoke. The smaller the
particle, the deeper it can travel into the lungs.
Much of this material is fairly benign – after all, people breathe in household
dust all the time with no ill effects other than a sneeze, and wood smoke from a
campfire causes watery eyes and barbecue-scented clothes but creates little permanent damage. However, some of the dust and smoke on industrial sites like a well
pad can pose significant risks to human health. Frack sand, for example, typically
consists of crystalline silica (SiO 2 ) in the form of quartz. Inhaling quantities of PM 10
quartz dust can lead to silicosis, an emphysema-like illness resulting from the scarring of lung tissue by the sharp particles. A more intense form of the disease from
acute dust exposure can even cause the alveoli of the lungs to be filled with dust
particles and permanently blocked (source: U.S. Centers for Disease Control [CDC]
websites).
In addition to quartz, silica can occur in four other different crystal structures
known as polymorphs: coesite and stishovite, which are fairly rare, and tridymite
and cristobalite, which are more common. Tridymite and cristobalite are hightemperature, low-pressure polymorphs of silica that typically occur in volcanic
rocks, but they can also form in lower temperature environments through processes
like the devitrification of silica-rich glass (Jones and Segnit 1972). Cristobalite is
particularly dangerous to inhale – it forms needle-like crystals similar to asbestos
that can penetrate and damage lung tissue. There is also evidence that cristobalite is
a potent carcinogen, and some studies indicate that other minerals fused to the edge
of cristobalite crystals can make the material even more toxic (Horwell et al. 2012).
The most common finer particulate matter (PM 2.5 ) encountered during drilling
and fracking is black smoke from diesel exhaust. Diesel emissions consist of vaporphase exhaust gases and diesel particulate matter or DPM. DPM is made up of PM 2.5
soot particles with a solid core of elemental carbon, surrounded by other chemical
substances attached to the carbon surface, including metals, sulfates, silicates and
aromatic hydrocarbons. Short term exposure to high concentrations of exhaust or
DPM can result in headaches, dizziness, and irritation of the eye, nose and throat. In
June 2012 the International Agency for Cancer Research (IARC) classified diesel
exhaust and DPM as known human carcinogens. Prolonged exposure can increase
the risk of cardiovascular, cardiopulmonary and respiratory disease, and lung cancer
(https://www.osha.gov/dts/hazardalerts/diesel_exhaust_hazard_alert.html;
accessed 10/3/2019).
The hazards posed by particulate matter emitted during drilling and fracking
operations on shale gas or tight oil well sites are similar in nature and intensity
compared to those from other construction sites. Oil and gas wells are basically
short-term construction projects and while they do emit dust and smoke during their
5.1 Particulate Matter