What Are The World Health Organization Guidelines for Indoor Air Quality?

The World Health Organization (WHO) is a specialized agency of the United Nations that addresses public health on a global scale. Among the many issues it monitors, indoor air pollution has been identified as a major public health concern in countries around the world—including in developed nations.

Surprisingly, indoor air can often be more polluted than outdoor air. Because it is more concentrated, indoor air pollution poses serious health risks in homes, workplaces, daycare centers, schools, healthcare facilities, and other enclosed environments.

To help residents and organizations manage this issue, the WHO has developed a comprehensive set of Indoor Air Quality (IAQ) Guidelines, presented across four major publications. These guidelines are based on decades of scientific research and are updated as new evidence emerges.

The Four Core WHO IAQ Guidelines

1. Air Quality Guidelines for Particulate Matter, Ozone, Nitrogen Dioxide, and Sulfur Dioxide

  • First published: 1987

  • Updated: 2005 (with periodic updates)

This foundational guideline focuses on the four most common indoor pollutants:

  • Particulate Matter (PM10 and PM2.5)

  • Ozone (O₃)

  • Nitrogen Dioxide (NO₂)

  • Sulfur Dioxide (SO₂)

These substances are either introduced directly through indoor activities (like cooking or heating) or enter from outside sources (like vehicle emissions). The WHO sets 24-hour and annual average limits (measured in micrograms per cubic meter, µg/m³) for each pollutant, offering targets to maintain indoor air at safe levels.

2. Dampness and Mould (2009)

This guideline highlights the health impacts of indoor mold and moisture. It focuses on:

  • Mold spores, fungi, and bacteria

  • Respiratory effects (especially for those with asthma or allergies)

  • Recommendations for ventilation and moisture control

The WHO stresses that mold can amplify the effects of other pollutants like PM2.5 and NO₂ and that good ventilation and humidity control are key to reducing these risks.

3. Selected Pollutants (2010)

This document expands the scope of the core guidelines by examining additional gases and chemicals found indoors, including:

  • Radon

  • Carbon monoxide

  • Formaldehyde

  • Benzo[a]pyrene

It offers detailed information on sources, health effects, exposure limits, and in some cases, testing and mitigation recommendations.

4. Household Fuel Combustion (2014)

This guideline focuses on pollution caused by residential cooking, heating, and lighting, particularly in low-income and developing regions. Key highlights include:

  • The health dangers of coal use in homes

  • Ventilation best practices for wood stoves, gas ovens, and other fuel-burning appliances

  • Clean technology and fuel alternatives

Although coal is rarely used in U.S. homes, this guide is still highly relevant—especially regarding gas stove ventilation and indoor nitrogen dioxide exposure, which has been linked to asthma and other respiratory conditions.

Why Particulate Matter Is a Major Concern

The WHO estimates that over 2 million premature deaths occur each year globally due to indoor air pollution, with particulate matter (PM) being a leading contributor.

  • PM10: Includes larger particles like dust, pollen, and mold fragments

  • PM2.5: Fine particles from fuel combustion (wood, gas, oil), more dangerous because they can penetrate deep into the lungs

The WHO provides strict daily and annual average exposure limits to help reduce health risks, especially among vulnerable populations like children and the elderly.

Indoor Pollutants: Ozone, Nitrogen Dioxide, and Sulfur Dioxide

In addition to particulate matter, these three gases are major indoor air pollutants:

  • Ozone (O₃): Often formed from outdoor pollution and indoor electronic equipment

  • Nitrogen Dioxide (NO₂): Commonly produced by gas stoves and vehicle exhaust

  • Sulfur Dioxide (SO₂): Typically from fossil fuel combustion

These gases can become more concentrated indoors than outdoors, especially in poorly ventilated areas. High exposure can cause respiratory irritation, inflammation, and long-term health complications.

WHO Guidelines vs. Mitigation

It’s important to note that WHO IAQ guidelines do not prescribe specific mitigation methods. Instead, they:

  • Establish safe exposure levels

  • Present the scientific rationale behind those thresholds

  • Provide the foundation for local health policies and building standards

However, the supplementary publications (like “Dampness and Mould” or “Household Fuel Combustion”) offer some practical recommendations, such as:

  • Improved ventilation

  • Avoiding certain fuel sources

  • Using air purifiers and dehumidifiers

  • Monitoring and addressing mold and moisture problems

WHO Recommendations for Homeowners and Businesses

While the WHO’s primary audience is policymakers, homeowners, tenants, and business owners can use these guidelines to evaluate their own indoor air quality and take proactive steps.

Here’s how:

  • Compare pollutant levels in your home to WHO recommended limits

  • Understand your exposure risk based on local outdoor air pollution

  • Schedule regular indoor air quality audits

  • Maintain consistent cleaning practices

  • Invest in air filtration, ventilation upgrades, and humidity control

  • Consider switching to clean fuel alternatives for heating and cooking

Final Thoughts

Indoor air pollution is a silent threat that affects millions of people worldwide—often without them knowing. By aligning your indoor air quality practices with WHO guidelines, you can significantly reduce health risks and create a safer environment at home or work.

At [Company_Name], we help homes and businesses in [Your City or Region] assess and improve their indoor air quality with expert testing, HVAC services, and practical solutions.

Want to breathe easier?
Call us today to schedule an IAQ consultation and discover how clean your air really is.

Your Local Indoor Air Quality Experts

Air Max HVAC has served Burbank and the surrounding areas for 20 years, and we look forward to many more years of high-quality service to come. Indoor air quality is an integral aspect of our trade, and we have an IAQ team that conducts audits, specializes in ventilation and filtration and installs and maintains air purifiers, dehumidifiers, humidifiers and germicidal lights. Our company also offers a full range of installation, maintenance and repair services for home heating and air conditioning, and we perform home energy audits in order to help our clients reduce their energy costs. Call us today to learn more about these services or to schedule an appointment.

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