Vehicle Emissions Gas Detection

The gases emitted by diesel and gasoline engines, Carbon Monoxide (CO) and Nitrogen Dioxide (NO2), present significant health risks when concentrations become too high. Both national and local codes are enforced to promote safety in structures where these gases can accumulate. Facilities such as parking structures, loading docks, and delivery warehouses can ensure compliance with these codes by installing a gas detection system that monitors gas levels and automatically starts ventilation as needed. This type of system can drastically reduce operating costs by limiting fan running time.

Shop Vehicle Emission Detectors


Do Sense Mounted

Where Vehicle Emission Detectors are Required

Distribution Centers

Parking Garages

Vehicle Depots

Loading Docks

Vehicle Maintenance Garages

How to Buy A Vehicle Emission Detection System


CTI published a helpful brochure that explains the best way to design a CO/NO2 detection system for your parking structure, distribution center, or vehicle depot.


vehicle emission brochure


Electrochemical Sensor Technology

The CTI DuoSense-M detector uses an electrochemical sensors which are accurate, reliable, and long lasting. Electrochemical cell technology is very specific to only CO and NO2 and will not alarm in the presence of other gases. These cells are housed in a well-vented polycarbonate enclosure which allows for the circulation of air while also protecting the cells from damage. The electrochemical sensor is an outstanding choice for personnel protection throughout most facilities.

Warehouse Worker

The Benefits of Vehicle Emissions Gas Detection

Parking Garages, Vehicle Depots, and Distribution Centers all have the potential to reach dangerously high levels of Carbon Monoxide and/or Nitrogen Dioxide gases. There are numerous institutions, societies, organizations and government agencies such as ASHRAE, IMC, UMC & UBC that have established codes and standards to address the limits of CO and NO2 for parking structures. Most building codes allow for demand-based ventilation in parking structures by monitoring CO & NO2 levels. Proper ventilation and air flow is necessary to protect people, but how often and how much ventilation is needed? Using CO and NO2 detectors to monitor gas levels and to turn on ventilation as needed not only protects people, but also saves on energy costs.

Choose CTI

Vehicle Emission Detectors are an integral part of a complete gas detection system.

Protect personnel and customers with CO and NO2 Detection. Use the link below to submit a quick quote request or call us at 866-394-5861 or email at

DuoSense-M Features


DuoSense Modbus Detector

Duo Sense Controller MVE

MVE Gas Detection Controller

CO and NO2 Sensor Elements

Fan Controller

Horn Strobe

Regulatory Concentrations of Interest

There are several CO and NO2 thresholds to consider


OSHA Limits

              • PEL=50ppm
              • TWA=25ppm
              • Ceiling= 200ppm

NIOSH Limits

              • REL=35ppm
              • Ceiling=200ppm


OSHA Limits

              • STEL=1ppm
              • Ceiling=5ppm

NIOSH Limits

              • STEL=1ppm

Alarm Levels and Recommended Outputs

See below table for CO an d NO2 detection alarm levels and outputs.

Gas Alarm Setpoint Action
CO 0-200ppm

Exact setpoints can be determined by the owner, but shall not exceed 200ppm.

  • activate mechanical, non-latching ventilation
  • activate audio-visual alarm
NO2 0-10ppm

Exact setpoints can be determined by the owner, but shall not exceed 10ppm

  • activate mechanical, non-latching ventilation
  • activate audio-visual alarm

Detector Placement

Based on typical construction, a sensor should be placed on every other support column in an alternating pattern. This will ensure that no area is left unprotected.
Detectors should be mounted approximately 3 – 5 feet above finished floor, in the typical human breathing zone.

Detection Range/Radius

Each DuoSense-M has a detection radius of 50 feet. The sensor element uses the diffusion method to evaluate and monitor the surrounding air quality and measure NO and CO2 levels.

Typical Parking Garage Layout