Hot Weather: Stale Air: How Summer Impacts Indoor CO2 Levels

As temperatures soar, we often focus on staying cool, but what about the air we breathe indoors? Summer heat waves don’t just affect outdoor comfort; they also impact indoor air quality, particularly the concentration of carbon dioxide (CO2) in homes, offices, and workplaces. When windows stay shut and HVAC systems are overworked, CO2 levels can rise to unhealthy levels, leaving occupants feeling tired, foggy, and unproductive, becoming at risk of serious health issues.

Understanding the connection between hot weather and CO2 buildup is essential for maintaining a safe, healthy indoor environment during the summer months.

Why CO2 Builds Up Faster During Summer Heat Waves

Summer often means longer days, busier buildings, and sealed windows to keep the heat out. While that may help your cooling bills, it also reduces natural ventilation, one of the most effective ways to control indoor CO2.

Here’s why CO2 levels spike in the heat:

• Closed windows and doors prevent fresh air from circulating.
• Air conditioning systems recycle indoor air without necessarily bringing in fresh outdoor air.
• Increased occupancy in restaurants, offices, and homes (think: tourists, remote work, or summer school) means more CO2 is produced by people breathing.
• Slower HVAC performance in extreme heat may reduce air exchange rates, leading to poor air circulation.

The Effects of High CO2 on Health and Productivity

High indoor CO2 levels don’t just make a space feel stuffy. They also affect how we think and feel. At levels above 1,000 parts per million (ppm), symptoms may include:

• Headaches
• Fatigue
• Drowsiness
• Difficulty concentrating
• Increased heart rate

At levels exceeding 2,000 ppm, these symptoms worsen and may include nausea or even cognitive impairment. This is especially concerning in commercial kitchens, classrooms, offices, and industrial workspaces, where peak summer conditions already pose safety risks.

How to Know If Your Air Is Unsafe

The tricky part? CO2 is colorless, odorless, and tasteless. You won’t know your air is compromised without a CO2 monitoring system.

Using a CO2 monitor allows you to:

• Track real-time air quality
• Set custom alerts when CO2 exceeds safe thresholds
• Pinpoint ventilation issues in specific rooms or zones
• Validate compliance with local codes (especially important for restaurants and commercial spaces)

HVAC Systems Aren’t Always Enough

While your HVAC system plays a critical role in keeping you cool, it may not address air quality effectively unless it's equipped with proper ventilation controls or outdoor air integration. Many standard systems recirculate indoor air without introducing enough fresh air—especially in older buildings or during heat advisories when outdoor air intake is minimized.

Simple Steps to Improve Indoor Air Safety During Summer

Staying cool and safe indoors this summer isn’t just about temperature. It’s about airflow, awareness, and action. Here are key steps to keep CO2 levels in check:

1. Improve Ventilation

• Use exhaust fans in high-use areas like kitchens or restrooms.
• Crack open windows early in the morning or evening when it's cooler outside.
  Install mechanical ventilation systems that draw in outdoor air.
• Read more about improving indoor air quality without an air purifier here and how to lower CO2 levels in your own home!

2. Monitor CO2 Levels

• Install CO2 monitors in high-traffic areas (conference rooms, kitchens, dining areas). Our Aerosphere Monitoring System provides real-time air quality tracking and is built to meet code compliance in commercial environments.
• Choose systems that provide live readings and alerts. For businesses, ensure monitors are code-compliant and professionally installed.

3. Maintain HVAC Equipment

• Change filters regularly.
• Check airflow rates and inspect ductwork.
• Schedule professional tune-ups, especially before and during high-demand seasons.

Join Us for Safe + Sound Week

As part of our commitment to workplace safety, we’re participating in Safe + Sound Week—an OSHA-backed initiative focused on proactive safety management. It’s the perfect time to reassess your air safety protocols, raise awareness among staff, and install tools like CO2 monitors that support long-term well-being.

Here’s the bottom line: summer heat waves can create invisible hazards indoors. When air isn’t circulating properly and CO2 builds up, people start to feel it—mentally and physically. Left unaddressed, poor indoor air quality can lead to decreased productivity, health risks, and even workplace safety violations.

Whether you manage a restaurant, operate a warehouse, or simply want a healthier home, now’s the time to take air quality seriously.

Final Thoughts

CO2 levels rise when the heat does—don’t let it catch you off guard. By investing in proper ventilation, using modern monitoring technology, and staying informed, you can create a safer, healthier space for everyone inside.

Need help monitoring your indoor air this summer? Visit our products page and contact us today to learn more about our CO2 monitoring systems and installation services