At 5:45 pm on Friday, January 3, 2020, the Chestertown Volunteer Fire Company was called to the 100 block of Chuch Alley for a Carbon Monoxide Alarm. This is an extremely narrow, close-quarters street in Downtown Chestertown, between Lawyers Row (Court Street) and Queen Street.

Units arrived to find a three (3) story historic home, built in 1730, undergoing home improvement work. Contractors working on the ground floor of the structure were pressure washing a part of their work area. Despite strongly-worded, generally accepted guidelines and instructions against the practice, contractors had been running a gasoline-powered pressure washer inside the structure.

Upon arrival a team of firefighters, wearing full-PPE (Personal Protective Equipment), to include SCBA (Self-Contained Breathing Apparatus)... and breathing compressed air, entered the structure with a universal gas-monitoring device. These devices are designed to detect and provide a concentration reading for several hazardous gases, including carbon monoxide. It should be noted, we are equipped with several gas-detectors. All of our devices are calibrated on a regular schedule to ensure they are operating correctly and provide accurate readings.

When we arrive at a Carbon Monoxide Investigation, our crews always wear respiratory protection when investigating. Carbon Monoxide is colorless, odorless and tasteless. It can be present in the structure at a level considered IDLH (Immediately Dangerous to Life & Health). In very high concentrations it can be fatal in a matter of minutes.

Immediately upon entering the structure, our gas detector was reading a concentration of 260 ppm (parts per million). A concentration this strong is considered a hazardous atmosphere. As a comparison, 50 ppm is the Maximum Allowable Concentration for continuous exposure in any eight (8) hour period. At 200 ppm, the onset of a headache, tiredness, dizziness and nausea will occur in 2 - 3 hours. At 400 ppm, a frontal headache occurs within 1 - 2 hours, then progresses to life-threatening after 3 hours. At 12,800 ppm, death can occur within 1 - 3 minutes.

Upon determination that a hazardous situation existed, crews immediately undertook ventilation operations to remove the carbon monoxide from the structure. Because of the age of the structure, it was found none of the windows would open. This complicated the ventilation process. In order to execute the operation, three (3) powerful ventilation fans were utilized to move air throughout the structure. Air monitoring continued throughout the entire ventilation operation, with firefighters remaining in their SCBA. Once air monitoring determined carbon monoxide levels had dropped to a safe-level, firefighters were allowed to remove their face-pieces and breathe room air.

Our readers are strongly cautioned against the practice of running internal combustion engines in any structure or enclosed space. It's extremely dangerous, injury and death can occur in a very short period of time. Before operation of any equipment operated by an internal combustion engine, the user should thoroughly read and understand the operator's manual, and strictly follow all safety instructions.

Anytime carbon monoxide is suspected, whether by a CO Alarm or people becoming ill in a short-period of time, immediate evacuation should be undertaken, This includes people and pets. Once outside in clean air, call 9-1-1 for emergency assistance.

We operated at this incident for about an hour and ten minutes. There were no injuries to civilians or emergency personnel.