A Complete Guide to Indoor Air Quality Standards (IAQ)

employee working in healthy buildings

Indoor concentrations of pollutants can be two to five times higher than outdoor levels. Considering that people spend approximately 87% of their lives indoors, with a third of that time at work, indoor air quality becomes a significant concern that impacts the health, comfort, and productivity of occupants. In fact, a 2022 Honeywell survey reports that 62% of office workers would consider leaving their jobs if their employers failed to address indoor air quality issues, and 89% agreed that the quality of the air they breathe has a direct impact on their health and well-being.

This is where Indoor Air Quality Standards (IAQ) play a key role. IAQ Standards are guidelines and regulations designed to ensure that the air quality inside buildings is safe and healthy to breathe. Established by various organizations, these standards set acceptable levels of indoor pollutants and provide recommendations for ventilation, air filtration, and other measures to maintain good air quality.

Health Effects of Poor IAQ

Poor air quality can have a wide range of adverse health effects on building occupants. These effects can vary from mild discomfort to serious health issues, depending on the type and concentration of pollutants present, as well as the duration of exposure.

 Short-term Health Effects Long-term Health Effects
  • Headaches
  • Fatigue
  • Trouble Concentrating
  • Eye Irritation
  • Nose Irritation
  • Throat Irritation
  • Lungs Irritation


What are the 4 Major Indoor Air Pollutants?

  1. Particulate Matter (PM): Includes dust, pollen, soot, smoke, and liquid droplets. Fine particles can penetrate deep into the lungs and even enter the bloodstream.
  2. Biological Pollutants: Such as mold, bacteria, viruses, animal dander, and dust mites. Mold spores can grow in damp areas and release mycotoxins, which are harmful to health.
  3. Chemical Pollutants: Including volatile organic compounds (VOCs), formaldehyde, and radon. VOCs and formaldehyde are known carcinogens and can have severe human health implications with prolonged exposure.
  4. Combustion Pollutants: Such as carbon monoxide, nitrogen dioxide, as well as smoke from tobacco, fireplaces, stoves, and heating systems.


What Causes Air Pollution?

Building materials such as asbestos, formaldehyde, and certain types of insulation can emit harmful pollutants into the air. Cleaning products are another common source, releasing volatile organic compounds (VOCs) and other chemicals that affect indoor air quality. Additionally, outdoor air infiltration plays a role, with pollutants from vehicle exhaust, industrial emissions, and pollen entering buildings and contributing to indoor air pollution.

Natural emergencies such as wildfires, extreme heat, volcanic eruptions, and dust storms can significantly worsen indoor air quality. Wildfires produce smoke and particulate matter, extreme heat can increase the concentration of ozone and other air pollutants, volcanic eruptions release ash and gases, and dust storms carry large amounts of dust and particulates into indoor spaces.


Explaining Different Indoor Air Quality Standards

There are different standards for Indoor Air Quality (IAQ) because various countries and organizations create guidelines based on their unique environmental conditions, health concerns, and technological capabilities. Factors such as local climate, prevalent building materials, industrial activities, and public health priorities influence these standards. Additionally, different regions have varying levels of resources and technological advancements to monitor and control air quality. As a result, IAQ standards are tailored to address the specific needs and challenges of each area, leading to a diverse range of guidelines and regulations globally.

Several prominent organizations are responsible for creating and updating these standards to help maintain good indoor air quality. These organizations play a crucial role in setting benchmarks for acceptable pollutant levels and providing recommendations for best practices in IAQ management:

International Organization for Standardization (ISO)

ISO develops and publishes international standards, including those related to indoor air quality. ISO standards provide comprehensive guidelines for air quality monitoring, assessment, and management. By establishing clear criteria for measuring and controlling indoor pollutants, ISO standards help organizations worldwide implement effective IAQ management systems.

Environmental Protection Agency (EPA)

EPA provides extensive resources and guidelines on indoor air quality, focusing on reducing exposure to common indoor pollutants such as radon, asbestos, and mold. While the EPA sets standards for outdoor air quality through the National Ambient Air Quality Standards (NAAQS), it also offers valuable guidance on improving IAQ in residential, commercial, and institutional buildings.

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)

ASHRAE has developed Standard 62.1, which is a widely recognized benchmark for ventilation and indoor air quality. ASHRAE Standard 62.1 specifies minimum ventilation rates and other measures necessary to achieve acceptable indoor air quality in commercial and institutional buildings. It provides detailed recommendations on controlling indoor air contaminants, ensuring adequate ventilation, and maintaining overall IAQ.

Occupational Safety and Health Administration (OSHA)

OSHA sets regulations to ensure safe and healthy working conditions in the United States. OSHA Guidelines for Indoor Air Quality focus on minimizing occupational exposure to hazardous substances and pollutants. OSHA provides permissible exposure limits (PELs) for various airborne contaminants and offers recommendations for maintaining good air quality in workplaces.

State and Local IAQ Standards Guideline

State and local Indoor Air Quality (IAQ) Guidelines across the United States vary significantly, reflecting regional priorities and challenges. Examples of state IAQ guidelines are outlined below:


The California Air Resources Board (CARB) sets stringent air quality standards, focusing on pollutants like particulate matter (PM10 and PM2.5), ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, and lead. CARB also regulates indoor air cleaners and promotes green building standards to enhance indoor air quality.


The Illinois Department of Public Health (IDPH) provides guidelines that include maintaining carbon dioxide levels below 1,000 ppm, carbon monoxide below 9 ppm, and formaldehyde below 0.1 ppm in offices and 0.03 ppm in homes. Recommendations also cover pollutants like hydrogen sulfide, ozone, nitrogen dioxide, and radon, emphasizing the importance of continuous monitoring and adequate ventilation.


In 2002, the Department of State Health Services (DSHS) implemented voluntary IAQ guidelines for government buildings and public schools based on the state Health and Safety Code. These guidelines set minimum risk levels for indoor air pollutants and highlight the critical role of proper ventilation and regular monitoring in maintaining healthy air quality.

Indiana and Ohio

Not only in Indiana and Ohio, but also in other states, health departments have established specific maximum exposure limits for CO2 in schools and state agency buildings. These guidelines aim to ensure a safe and healthy indoor environment by limiting CO2 levels to prevent adverse health effects.

New York

The guidelines for indoor air quality in New York do not include specific thresholds for pollutants that are based on human health risks. For one, the state Clean Indoor Air Act has effectively reduced smoking and vaping activities, while its Indoor Allergen Hazards law mandates building owners to address and mitigate mold and pest infestations to ensure healthier indoor environments.

 Benefits of Compliance Challenges in Compliance
  • Improved health and comfort for building occupants
  • Increased productivity
  • Reduced absenteeism
  • Enhanced employee satisfaction
  • Legal compliance and reduced liability
  • Improved reputation and public image
  • Potential cost savings from reduced healthcare expenses
  • Better indoor environmental quality
  • Financial constraints
  • Lack of awareness and education
  • Outdated HVAC systems
  • Variability in local regulations
  • Technical complexities in monitoring and control
  • Resistance to change
  • Maintenance and operational challenges
  • Limited access to advanced technologies


How to Improve Indoor Air Quality

fresh air inside the workplace

Improving indoor air quality is essential for maintaining a healthy and comfortable environment. Here are some best practices to improve IAQ in offices and other indoor environments:

  1. Increase Ventilation: Ensure that the workplace is well-ventilated by regularly opening windows and doors to allow fresh air to circulate. Utilize exhaust fans in restrooms and kitchens to remove moisture and pollutants. Maintain HVAC systems regularly and replace filters frequently to ensure efficient airflow and pollutant removal.
  2. Control Humidity Levels: Keep indoor humidity levels between 30-50% to prevent mold growth, which can negatively impact health. Use dehumidifiers in areas prone to dampness, such as basements. Promptly repair leaks and clean up water spills to maintain optimal humidity levels.
  3. Eliminate or Reduce Pollutant Sources: Prohibit smoking indoors and minimize the use of products that emit volatile organic compounds (VOCs), such as certain paints, varnishes, and cleaning supplies. Choose eco-friendly and low-emission products for office cleaning and maintenance. Install carbon monoxide detectors and conduct regular checks for gas leaks to eliminate potential sources of indoor air pollution.
  4. Use Air Purifiers: Deploy high-efficiency particulate air (HEPA) filters to capture dust, pollen, and other airborne particles. Place air purifiers in high-traffic areas or rooms with limited ventilation to enhance air quality.
  5. Employee Education and Training: Educating employees about the importance of IAQ and how they can contribute to maintaining it is essential. This includes proper usage of cleaning products, reporting issues, and understanding the impact of indoor pollutants.
  6. Implement Green Building Practices: Choose building materials and office furnishings that emit low levels of VOCs to reduce indoor air pollutants. Incorporate indoor plants that help purify the air, such as spider plants, snake plants, and peace lilies, to naturally enhance air quality.


Technologies to Monitor and Improve IAQ

Air Sensor Technology is a leading solution for monitoring and improving indoor air quality in real-time. These sensors detect various pollutants and environmental conditions, such as particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), carbon dioxide (CO2), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). Utilizing advanced sensing elements like electrochemical, optical, and metal oxide sensors, these devices can provide accurate and continuous data on air quality.

Air sensors are often integrated into portable devices, fixed monitoring stations, or smart systems, allowing for widespread and versatile applications. They are crucial in identifying air pollution sources, assessing the effectiveness of air quality improvement measures, and providing the public with critical health information. The increasing awareness of the health impacts of air pollution has driven advancements in air sensor technology, making it more affordable and accessible for both personal and industrial use.


FAQs on Indoor Air Quality Standards

What is considered good indoor air quality?

Good indoor air quality is characterized by low levels of pollutants, such as particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), carbon dioxide (CO2), carbon monoxide (CO), and other harmful gases, ensuring healthy and comfortable indoor environments.

What is poor indoor air quality?

Poor indoor air quality is indicated by high concentrations of pollutants like PM2.5, VOCs, CO2, CO, mold, and other contaminants that can cause health issues, discomfort, and adverse effects on productivity and well-being.

What reduces indoor air quality?

Indoor air quality can be reduced by sources like tobacco smoke, cooking fumes, chemical emissions from building materials and furnishings, poor ventilation, mold, and outdoor pollutants infiltrating indoor spaces.

How can I measure indoor air quality?

Indoor air quality can be measured using air quality monitors or sensors that detect and report levels of various pollutants. These devices can be standalone or integrated into smart home systems for continuous monitoring.

What is the indoor air limit?

Indoor air limits vary based on guidelines from organizations like the EPA and the World Health Organization (WHO). For example, the WHO recommends PM2.5 levels not exceed 10 µg/m³ annually or 25 µg/m³ over 24 hours to maintain good indoor air quality.


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The material provided in this article is for general information purposes only. It is not intended to replace professional/legal advice or substitute government regulations, industry standards, or other requirements specific to any business/activity. While we made sure to provide accurate and reliable information, we make no representation that the details or sources are up-to-date, complete or remain available. Readers should consult with an industrial safety expert, qualified professional, or attorney for any specific concerns and questions.


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Author: Herbert Post

Born in the Philadelphia area and raised in Houston by a family who was predominately employed in heavy manufacturing. Herb took a liking to factory processes and later safety compliance where he has spent the last 13 years facilitating best practices and teaching updated regulations. He is married with two children and a St Bernard named Jose. Herb is a self-described compliance geek. When he isn’t studying safety reports and regulatory interpretations he enjoys racquetball and watching his favorite football team, the Dallas Cowboys.