Do you live in area where homes are fumigated by tenting them? I remember seeing these garishly colored tarps reminiscent of striped circus tents covering suburban homes in California when I was a kid.

Have you ever wondered what those houses smelled like after the fumigation? It turns out that these homes are being tented to trap in carbon dioxide (CO2). The only poison the fumigators are using is CO2. You can kill a family of roaches living in your walls by pumping enough CO2 gas into the room and leaving the levels elevated.

If CO2 kills roaches, then this begs the question: What happens to you if there is a large CO2 leak in your growroom? In the compressed gas and cryogenics industry, CO2 is often called rat gas for its murderous properties.

As far as CO2 is concerned, we are just big rats. Inhaling CO2 can cause loss of consciousness after only a single breath. Without immediate rescue and administration of first aid, you may never wake up.

The average ambient CO2 level with good fresh air exchange is approximately 340-400 parts per million (ppm). This level varies by season, elevation and ventilation, and can even be influenced by how many people are in a building. In an effort to maximize yields, a gardener may choose to increase the amount of CO2 in their garden as high as 900-1,600 ppm. OSHA regulations cap safe workplace levels at 5,000 ppm, in a time-weighted average, for an eight-hour shift.

This level does not have significant health effects on human beings, but at levels of 100,000 ppm, you may experience a coma, asphyxiation and death.

How can a person tell the difference between 5,000 and 100,000 ppm? The answer is simple, really: one kills you, the other doesn’t.

In all seriousness, the only way to tell how much CO2 is in a room is with an electronic gas monitor. You need to be sure to understand the difference between a carbon monoxide detector and a carbon dioxide detector.

Your local big box store does not sell carbon dioxide detectors. This means you will likely have to purchase one through your local indoor gardening store or online.

A few cities in the United States have begun introducing mandatory CO2 safety programs. For instance, Denver, Colorado, is implementing a new regulatory framework. Their plan will mandate the use of safety monitors for many businesses using CO2 cylinders. Denver’s plan is intended to guarantee a safe environment for employees and the public alike.

The only way to ensure a safe environment is to require gas monitoring. Rather than affecting only controlled-environment farms, the new restrictions will be much more broadly targeted. The impact will be felt in restaurants, bars, convenience stores, medical facilities, pools and many other locations.

As a home gardener, you will not be required to comply, but that doesn’t mean you are in the clear.

Types of Carbon Dioxide Monitors

There are three main types of monitors to consider. All three varieties will alert you to excessive CO2 levels with an alarm and a strobe indicator. You should only consider units that have audio and visual alerts.

Fixed Monitor/Alarm Only – As the name infers, this type of system is fixed, or permanently mounted in its location. Its only function is to alert you to dangerously elevated CO2 levels. The critical components are the sensor head, the siren and the strobe. Large facilities may require several sensors.

Portable Devices – A portable monitor attaches to a belt or other clothing with a clip. This type of monitor is designed to be worn while working around potentially hazardous environments. Since CO2 is heavier than air, portable monitors should be worn low on the body. If you’re heading downstairs, this placement can alert you to a problem more quickly. For larger areas, you may be better off with a few portable monitors attached to employees who are roaming around the property.

Integrated Monitoring – An integrated monitor can be designed to control the CO2 delivery equipment. When levels are low, the sensor tells the CO2 solenoid to open and provide gas. When readings reach the desired level, the sensor will signal the control unit to shut off the CO2 supply. If the CO2 reaches dangerous levels, the integrated monitor will sound the alarm. A high-quality system may even control an automatic shutoff safety device, contact the fire department or alarm company, and turn on ventilation fans.

Read More: The Symbiotic Relationship between CO2 and Ventilation

Best Sensor Placement for CO2 Detection

In a commercial environment, your sensor placement may be regulated by local authorities. Many restaurant and convenience store chains have nationwide policies regarding CO2 monitor/alarm installation in their stores. These policies and regulations will likely continue to spread.

As a small business owner or home gardener, you should visit your local indoor gardening showroom or contact your local gas provider to learn more about CO2 safety devices.

Purchasing, installation and maintenance of a safety device such as a CO2 monitor is not a one-size-fits-all solution. For example, a monitor designed for a restaurant is not a good fit for an indoor garden, as it will alert constantly in the presence of supplemental CO2.

When installing your CO2 sensor, you need to locate it where it will be most effective. The placement of the sensor head is critical. Since CO2 is heavier than air, the sensor should be near the floor to accurately detect concentrated levels. CO2 sensors should be placed approximately 12-in. above the floor.

When your lights and fans are on, you may have plenty of circulation to prevent CO2 from settling near the floor. Once the lights and fans turn off, any residual CO2 will pool up in the lowest portions of the space. Anyone working near the floor could be in particular danger, including children and pets.

It is important to place the signaling device of the alarm in an area that will alert you to the hazard before you are actually in danger. Place the alarm siren near the stairs if you have a garden in a lower level of your home or business. You should make sure you can hear the siren and/or see the strobe from the top of the stairs. This way you will know not to enter the area until it has been properly ventilated and the alarm has stopped sounding.

Tips & Tricks for Installing CO2 Monitoring Equipment

Here are a few additional things you should know when looking for a CO2 safety monitoring system.

You Get What You Pay For – When it comes to safety equipment, you should expect to spend a little cash. A quality gas monitoring system is an investment in your long-term safety. An incident involving a visitor or employee might be the end of your business, or worse.

Bump Testing – A bump test is a simple procedure that involves flooding your gas sensor with a short-term burst of concentrated gas, simulating a CO2 leak. If your gas sensor doesn’t respond to a bump test, you should have it checked immediately. A quality sensor package will include instructions on how to test your sensor. Bump tests should be conducted on a weekly basis. A failed bump test is a sign your system needs to be calibrated or repaired.

All Gas Monitors Need to be Calibrated – Just because something has power doesn’t mean it is working properly. Only regular testing and calibration can ensure the readings you are getting are accurate. Sensors tend to drift over time. Auto-calibrating safety monitors may not read correctly over time. These “self-calibrating” units are often designed to assume the level it sees is normal. If it takes enough high level readings, it will make that high level the new normal. A sudden spike may trigger an alarm, but a slow rise over several months may fool the software.

Do You Trust It to Keep You Alive? If Not, Toss It – Your CO2 monitoring system is designed to keep people safe. Don’t let a false sense of security or complacency set in. Every time you look at your monitor, ask yourself this question: “Do I trust this device to save my life?” If your answer is no, get a new system or seek professional assistance.

All Gas Sensors Are Consumable – The typical lifespan of a gas sensor ranges from six months to 10 years. The manufacturer of your system should provide details on sensor testing and calibration intervals and procedures, but don’t believe everything you hear. Some monitors say they last forever and never need calibration.

Use caution when purchasing from companies with these extraordinary claims. A quality gas monitor is designed to have the sensors calibrated and replaced when required. You don’t have to replace the entire unit, just the sensor. Sensor replacement is a fraction of the cost of a new system. After replacement, the new sensor will need to be calibrated as well.

Having the appropriate safety CO2 safety equipment set up in your growroom will allow you to focus on other concerns. Wouldn’t you rather be spending your time mastering light levels, pest control and nutrient schedules than trying to guess how much CO2 you have in your growroom?

Be safe out there.

Read Next: CO2 Enrichment, Acclimation, and Efficiency in Hydroponic Growing