Indoor occupational risk assessment of traffic-related nitrogen dioxide in public hospitals, Alexandria, Egypt

The U.S. Environmental Protection Agency ranks indoor air quality as one of the most prominent environmental problems However, limited research has addressed indoor air quality in Egypt, particularly in highly sensitive environments such as hospitals. Moreover, traffic-related pollutants such as nitrogen dioxide (NO₂) are rarely investigated as risk factors in hospitals. Therefore, this study assessed the occupational exposure risks associated with traffic-related NO₂ in four public hospitals on different main streets in Alexandria, Egypt. This study was carried out through indoor nitrogen dioxide sampling during the morning shifts in four public hospitals in Alexandria, Egypt. Hospitals were selected and categorized based on the traffic congestion levels of their main streets. The traffic congestion categories included heavy, moderate, and low congestion areas as well as on-sea road areas. One hospital was randomly chosen from each category. The results of the present study showed the highest NO₂ exposure recorded among hospital staff located in the heavy traffic area during hot months, whereas the lowest exposure observed was among on-sea hospital staff. The results indicated that outdoor traffic emissions were the primary source of indoor NO₂ exposure. The results showed a strong and statistically significant correlation with nearby traffic congestion. The risk of indoor nitrogen dioxide concentrations during hot and cold months was high at most indoor locations: 72.7% and 63.6% of locations in the heavy traffic hospital during hot and cold months, respectively. Moderate risk was observed at most of the locations at moderate traffic hospital (77.8%), the sea-road hospital (57.1%), and the low traffic hospital (54.5%) during both hot and cold months. This study concludes that NO₂ concentrations increase with traffic congestion, and the risk factor was found to be moderate to high at most of the measured indoor locations in the four hospitals. It is recommended to reduce NO₂ exposure among hospital staff and patients by utilizing mechanical ventilation systems with air filtration.