Carbon monoxide is colorless and odorless, so a sounding CO alarm or symptoms around fuel-burning equipment should be treated as a safety issue first and a documentation issue second.

Your goal is not to create dramatic evidence. Your goal is to create believable evidence showing what happened, where it happened, when it happened, how often it happened, and when the landlord was told.

Document safely first

A CO alarm or suspected poisoning can be life-threatening. Move to fresh air and call 911, the fire department or the gas utility as directed locally.

Capture the condition clearly

  1. Start wide. Take one photo that identifies the room, wall, fixture, doorway, appliance, common area or other location.
  2. Move closer. Take medium and close images showing the specific defect. Use a ruler, thermometer, clock, work-order screen or other ordinary reference only when it helps explain the condition.
  3. Use video for movement, sound or recurrence. Leaks, flickering, pests, failed locks, alarms and repeated system failures are often easier to understand on a short video than in a still photo.
  4. If an alarm sounds, leave first and follow emergency instructions; documentation can wait.
  5. After the scene is declared safe, photograph the alarm, appliance, service tag and any visible soot or vent damage without disassembling equipment.
  6. Save fire-department, gas-utility, HVAC technician and maintenance reports.
  7. Record symptoms and timing factually, but do not re-enter a dangerous area to recreate the event.
  8. Send written notice. State the problem, exact location, when it began, whether it is getting worse, and what repair or action you are requesting. Save proof of delivery.
  9. Build one timeline. Put photos, work orders, management replies, inspection dates, receipts and third-party reports in date order. That timeline can become the backbone of a code complaint, legal-aid intake or RentalFacts listing.

Make your evidence harder to attack

Keep the affected area reasonably clean when cleanliness is relevant to the dispute. Do not stage damage, exaggerate symptoms, edit images in a misleading way, or provoke a neighbor or employee just to get a reaction on camera. Preserve original files whenever possible.

RentalFacts tip: A strong public report should separate what you personally observed from what an inspector, technician, doctor, neighbor or government agency reported.