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  • September 2, 2025

The Role of CO2 Monitoring in Modern Workplace Safety Programs

Ensuring healthy indoor air quality has become a core part of workplace safety, and carbon dioxide (CO2) monitoring plays a critical role in this effort. CO2 is a colorless, odorless gas that builds up naturally in occupied indoor spaces due to human exhalation and other sources. High CO2 levels are not usually directly toxic at the concentrations found in offices, but they serve as an important indicator of ventilation effectiveness and overall indoor air quality. Inadequate ventilation can lead to a stuffy, uncomfortable environment and even affect employees’ well-being and productivity.

Why Monitor CO2 in the Workplace?

Monitoring CO2 provides a quick way to gauge if a workspace is getting enough fresh air. Since people constantly exhale CO2, indoor levels tend to rise in crowded or poorly ventilated areas. Outdoor air is roughly 400 ppm (parts per million) CO2, but indoor concentrations can range from a few hundred ppm up to over 1,000 ppm in occupied rooms with limited ventilation. The key factors are the number of people, the time spent in the space, and the amount of fresh air being supplied. Measuring CO2 is an indirect ventilation check – if CO2 is accumulating, it suggests the space isn’t getting enough outside air for the number of occupants.

Safe CO2 Levels and Official Guidelines

Workplace safety organizations and building standards provide guidance on acceptable indoor CO2 concentrations. Here are key benchmarks from renowned authorities:

OSHA Permissible Exposure Limit (PEL): OSHA (Occupational Safety and Health Administration) primarily treats CO2 as an asphyxiant gas hazard at very high levels. OSHA’s occupational exposure limit for CO2 is 5,000 ppm averaged over an 8-hour workday. This is a safety threshold meant to prevent acute CO2 toxicity in industrial settings – levels this high are uncommon in normal offices. (For reference, some guidelines also note a short-term limit around 30,000 ppm for 15 minutes, and concentrations ~40,000 ppm are immediately dangerous to life and health.) While 5,000 ppm is the legal limit, best practice is to keep indoor CO2 far below this ceiling in everyday workplaces for comfort and wellness.

ASHRAE Ventilation Standards: Rather than a strict CO2 limit, ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) sets ventilation rate standards to ensure adequate fresh air per person. For example, ASHRAE Standard 62.1 recommends around 15–20 cubic feet per minute of outdoor air per person in offices and classrooms, which generally keeps indoor CO2 below about 1,000 ppm for most spaces. 1,000 ppm has long been used as a rule-of-thumb comfort target for CO2. While ASHRAE does not explicitly require staying under 1000 ppm in its standards, maintaining roughly 600–1,000 ppm indicates that ventilation is likely sufficient for occupant comfort. In fact, ventilation rates that keep CO2 under 1000 ppm tend to create indoor conditions acceptable to most people.

WHO and Public Health Guidance: In the context of infection control (e.g. COVID-19), health authorities emphasize ventilation. The World Health Organization (WHO) recommends providing at least 10 liters/second of fresh air per person in offices (roughly aligning with ASHRAE’s rates) to reduce respiratory aerosol risks. Since measuring airflow directly can be technical, experts often use CO2 as a proxy. The UK’s SAGE group and other experts advise keeping CO2 below 1000 ppm in general indoor spaces, and below ~800 ppm in higher-risk, high-occupancy settings like gyms or choir rooms. If indoor CO2 ever reaches 1500 ppm or more, it’s considered a red flag indicating very poor ventilation that should be addressed immediately.

CDC Recommendations: The U.S. CDC has recently issued practical ventilation guidelines using CO2 monitors. “A portable CO2 monitor can help determine how stale or fresh the air is. Readings above 800 ppm suggest you may need to bring more fresh air into the space,” according to the CDC. In other words, ~800 ppm CO2 is a benchmark for good ventilation in many scenarios. The CDC advises establishing a baseline CO2 level for each room under optimal ventilation, and if readings exceed about 110% of that baseline, there may be an HVAC issue or ventilation reduction that needs correction. This approach encourages proactive monitoring to ensure ventilation systems keep performing well over time.

By considering these guidelines together, many organizations choose a tiered approach to CO2 levels in workplaces:

  • Optimal: 600–800 ppm (excellent ventilation, akin to outdoor-fresh air in the room)
  • Acceptable: 800–1000 ppm (generally adequate ventilation for most situations)
  • Poor: 1000–1500 ppm (needs improvement – likely causing stuffiness and affecting comfort)
  • Action Required: >1500 ppm (inadequate ventilation – take immediate steps to increase fresh air).

Effects of Elevated CO2 on Health and Performance

High indoor CO2 levels affect comfort, focus, and overall air quality. Research shows that even moderate levels around 1000 ppm can impair decision-making and concentration, while levels above 1500–2000 ppm often cause drowsiness, headaches, and fatigue. Prolonged exposure to several thousand ppm may lead to dizziness or nausea, and extremely high levels pose serious health risks. More commonly, elevated CO2 signals poor ventilation, which allows other pollutants to build up and results in complaints of stuffy, uncomfortable air. Keeping CO2 low ensures employees stay alert, productive, and healthier.

Best Practices for Managing Indoor CO2

Maintaining safe CO2 levels starts with proper ventilation—ensuring HVAC systems deliver enough fresh air and are regularly maintained. Where possible, natural ventilation or portable air cleaners can also help. Continuous CO2 monitoring provides real-time insight into air quality, allowing facilities to spot problem areas and act quickly. Setting clear thresholds, such as alerts when levels exceed 1000 ppm, ensures issues are addressed before they escalate. Using data to adjust ventilation, manage occupancy, and educate staff about CO2 monitoring fosters a healthier environment. Ideally, CO2 should remain below 800–1000 ppm to keep workplaces fresh, safe, and comfortable.

CO2 Monitoring Solutions: Devices Like HibouAir

Technology has made it easier than ever to continuously monitor indoor air quality. There are now plug-and-play CO2 monitoring devices that can be deployed in workplaces without complex installation. For example, HibouAir is an indoor air quality monitor that provides real-time measurements of CO2 along with other environmental parameters. HibouAir’s multi-sensor design tracks carbon dioxide levels, temperature, humidity, ambient light, atmospheric pressure, and volatile organic compounds (VOCs) to give a complete snapshot of your indoor environment.

Devices like this are compact and wireless, connecting via Bluetooth or Wi-Fi for easy data access. With continuous monitoring, facility managers can set up alerts when CO2 approaches set thresholds, and view trends over hours or days to identify ventilation issues. For instance, if CO2 steadily rises every afternoon in a certain area, you’ll spot it in the data and can investigate (perhaps an air damper that isn’t opening or an overcrowded meeting area). By keeping CO2 levels in check, organizations can optimize the indoor space for productivity, comfort, and well-being. In other words, a good monitor not only warns of potential safety issues but also empowers you to fine-tune the environment for maximum occupant comfort and efficiency.

CO2 monitoring has become an essential component of modern workplace safety and wellness programs. It provides a simple, objective measure of whether your indoor spaces are well-ventilated and healthy. By adhering to guidelines from OSHA, ASHRAE, WHO and others, organizations can maintain CO2 at levels that ensure worker safety and comfort – typically keeping concentrations under about 1000 ppm, with 600–800 ppm as a gold standard for optimal ventilation. Regular monitoring with reliable devices helps catch any ventilation issues early, allowing facility managers to address them before they impact employees. The result is a workplace that not only meets safety requirements but also supports employee alertness, productivity, and overall well-being. In short, CO2 monitors are valuable tools for creating healthier, safer work environments, and implementing them alongside good ventilation practices is a smart investment in your organization’s most important asset – its people.

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