Natural Ventilation in Iranian Bakeries: Identifying Gaps and Proposing Guidelines for Future Respiratory Pandemics Such as COVID-19

Aims: 
This study aimed to evaluate natural ventilation practices in traditional bakeries in Semnan Province, Iran, and assess their compliance with Iranian ventilation standards. It also desired to develop preliminary guidelines for improving ventilation to mitigate risks during potential respiratory pandemics such as COVID-19.
Methods: 
This descriptive analytical study was conducted in the winter of 2023 in Semnan Province, located in northeastern Iran. The research evaluated 142 bakeries through observational surveys and measured key ventilation indicators, including airflow (L/s per m²), airflow per person (L/s per person), and air changes per hour (ACH). To develop preliminary guidelines, these ventilation indicators were reassessed across four scenarios, with openings set at 25%, 50%, 75%, and 100% of their maximum capacity.
Results: 
The findings revealed that while 94.4% of the bakeries adhered to fundamental airflow guidelines, only 40.8% achieved the ACH standards, a key measure of indoor air quality (IAQ). Even with fully open ventilation openings, only 95.1% and 64.8% of the studied establishments met Iran’s natural ventilation standards for airflow and ACH, respectively.
Conclusions: 
The study highlights noncompliance with ACH standards in bakeries, underscoring the need for improved ventilation strategies. Proposed guidelines recommend maintaining a minimum ventilation opening area of 10% of the floor area and ensuring that mechanical ventilation systems operate continuously and optimally during activity hours. These measures are essential for enhancing IAQ and reducing the risk of potential respiratory pandemics such as COVID-19 in high-risk environments such as bakeries.