Mosques and Indoor Air Quality: High Occupancy, Long Dwell Times.

Places of worship are among the most important shared indoor environments in the GCC. Mosques, churches, temples, and prayer halls welcome large numbers of people daily, often multiple times a day, and play a central role in community life. Yet from a building performance perspective, they present a unique and frequently overlooked challenge: high occupancy combined with long dwell times in enclosed, air-conditioned spaces.

As expectations around health, comfort, and sustainability grow, indoor air quality (IAQ) in places of worship deserves far greater attention.

A Unique Occupancy Profile

Unlike offices or retail spaces with relatively predictable occupancy, mosques experience:

• Very high occupant density during prayers, particularly Friday (Jumu’ah), Taraweeh, and Eid

• Rapid changes in occupancy, from near-empty to full within minutes

• Extended dwell times, especially during sermons and evening prayers

• Diverse age groups, including children and the elderly

These conditions significantly increase the concentration of carbon dioxide (CO₂), aerosols, and airborne contaminants - especially in sealed buildings typical of the GCC climate.

Air Quality and Health Considerations

In crowded indoor environments, the air we breathe becomes a shared resource. Poorly managed IAQ in places of worship can:

• Facilitate the spread of respiratory illnesses

• Increase fatigue, headaches, and discomfort during prayer

• Affect vulnerable groups, including the elderly and those with respiratory conditions

• Reduce concentration and spiritual comfort

The COVID-19 pandemic highlighted how airborne transmission can occur in high-occupancy indoor spaces, but the underlying IAQ challenges existed long before—and remain today.

The GCC Climate Factor

In the Gulf region, extreme heat and humidity require mosques to operate with:

• Continuous or near-continuous air-conditioning

• Limited natural ventilation

• High levels of air recirculation

While this ensures thermal comfort, it can also allow contaminants to accumulate if air is not properly cleaned and refreshed. Simply increasing outdoor air is often impractical due to energy, humidity, and comfort constraints.

This makes air cleaning and purification an essential complement to ventilation - not an optional extra.

Design and Operational Challenges

Many mosques were designed before IAQ became a mainstream consideration. Common challenges include:

• HVAC systems sized primarily for peak thermal load, not air quality

• Limited zoning or control for variable occupancy

• Minimal air filtration beyond basic requirements

• Lack of IAQ monitoring to understand real conditions

As a result, IAQ performance is often unknown - and unmanaged.

Mosques and Indoor Air Quality in Places of Worship

Improving indoor air quality in mosques and other places of worship does not require compromising energy efficiency or comfort. Effective strategies include:

• Air purification technologies that clean recirculated air, reducing airborne bacteria, viruses, allergens, and odours

• Enhanced filtration and air distribution, ensuring clean air reaches the breathing zone

• CO₂ and IAQ monitoring, enabling facility managers to respond to real occupancy patterns

• Energy-conscious solutions that support sustainability goals without increasing cooling loads

When integrated correctly, these measures help maintain healthier air even during peak attendance.

Protecting Worshippers, Supporting Communities

Mosques are spaces of reflection, focus, and community connection. Ensuring clean, healthy air supports:

• Worshipper comfort and well-being

• Public health protection

• Confidence among congregants

• Responsible stewardship of community assets

In a region where mosques are used daily and often intensively, IAQ should be viewed as a core operational responsibility.

Conclusion: Clean Air as an Act of Care

Places of worship are built to serve people. In today’s world, that responsibility extends beyond architecture and aesthetics to the quality of the air inside.

Across the GCC, Mosques and Indoor Air Quality is not about technology alone - it is about care, inclusivity, and long-term resilience.

Healthy air enables worshippers to breathe comfortably, remain focused, and gather with confidence - every prayer, every day.