Which of the following choices is NOT considered an environmental stressor?

A24-year-old g4p2 woman at 34 weeks gestation complains of a cough and whitish sputum for the last three days. she reports that everyone in the family has been sick. she reports a high fever last night up to 102°f (38.9°c). she denies chest pain. she has a history of asthma with no previous intubations. she uses an albuterol inhaler, although she has not used it this week. vital signs are: temperature 98.6°f (37°c); respiratory rate 16/minute; pulse 94 beats/minute; blood pressure 114/78; peak expiratory flow rate 430 l/min (baseline documented in the outpatient chart = 425 l/min). on physical examination, pharyngeal mucosa is erythematous and injected. lungs are clear to auscultation. white blood cell count 8,700 mcl; arterial blood gases on room air (normal ranges in parentheses): ph 7.44 (7.36–7.44); po2 103 mm hg (> 100); pco2 26 mm hg (28–32); hco3 19 mm hg (22–26). chest x-ray is normal. what is the correct interpretation of this arterial blood gas?