Objective To analyze the distribution characteristics of infectious respiratory particles (IRPs) in hospital waiting rooms, and explore the impact of indoor air environmental on the distribution characteristics of bacterial IRPs. Methods In the summer and winter of 2024, nine waiting rooms in non-infectious departments of three ter-tiary hospitals in a district of Beijing were selected for on-site investigation on basic conditions. Concentration and distribution of particle diameter of cultivable bacteria from 36 air specimens collected by the impacting method were analyzed. Cyclone method was employed to collect 36 IRPs specimens. Major respiratory pathogens were analyzed by fluorescence polymerase chain reaction (PCR). Results The median of the total bacterial count in IRPs in the waiting rooms in summer was 1 035 CFU/m³, which was higher than that in winter (295 CFU/m³), with statistically significant difference (P < 0.05). The orders of medians of the total bacterial count from IRPs of different types in the waiting rooms in both summer and winter were as follows: emergency department waiting room < respiratory department waiting room < pediatric waiting room < general outpatient waiting room. There was no statistically significant difference in the total bacterial count among different waiting rooms (P > 0.05). Particle diameter of bacterial IRPs in the waiting rooms in summer and winter mainly distributed in the range of < 4.7 μm, accounting for 73.77% and 69.44%, respectively. The total number of bacteria in IRPs in the waiting rooms was positively correlated with indoor air temperature, relative humidity, PM₁₀, and PM_2.5 (all P < 0.01), while negatively correlated with indoor wind speed (all P < 0.01). The types of respiratory infectious and non-infectious pathogens detected from IRPs in different types of waiting rooms were different between summer and winter. The pathogens detected in summer were mainly concentrated in respiratory non-infectious pathogens (Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus). In winter, respiratory infectious pathogens (virus and Mycoplasma pneumoniae) were detected. The types of detected pathogens in different types of waiting rooms were different. Non-infectious respiratory pathogens detected from IRPs in winter were mainly Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. Conclusion Particle diameter of bacterial IRPs in the waiting room is mainly < 4.7 μm. These particles can enter the lower respiratory tract of human body, and pose potential risk to health. The detection of main infectious and non-infectious respiratory pathogens from IRPs in waiting rooms suggests risk of exposure to infection for patients and healthcare workers.