**2. Life cycle risks of hydraulically fractured wells**

As with any fossil fuel production, a hydraulically fractured ('fracked') well has the potential to release air and water pollutants, pose physical and public safety hazards, and contribute to psychosocial stressors for nearby residents and communities. The life cycle of a well consists of several phases shown in **Figure 1** [4].

Each life cycle phase generates emissions, effluents and waste that may pose health risks to workers and nearby communities. They are discussed in this chapter according to their exposure pathway, e.g., via air or water, and by exposed population groups, e.g., oil and gas workers or nearby communities. It is noted that the likelihood of health impacts is generally a function of the hazardousness of the chemical and nonchemical stressor (i.e., the stimulus causing undesirable health

**Figure 1.** 

*The typical life cycle of an unconventional oil or gas well.* 

*Human Health Risks of Unconventional Oil and Gas Development Using Hydraulic Fracturing DOI: http://dx.doi.org/10.5772/intechopen.82479* 

effects), the exposure duration and the pathway. The spatial reach of the stressor is also important and may range from the immediate well-pad area to local (up to 10 km), regional (up to 100 km) and local distances (farther than 100 km). Thus, the following sections are organized to describe human health risks according to pathway and spatial distance.
