Passenger comfort and ozone pollution exposure in an air-conditioned bus microenvironment.

Ground-level ozone is the primary source of air pollution in China, particularly during the warmer months. In this study, we investigated the exposure status of ozone pollution and the temperature distribution in an air-conditioned bus in Jinan during the evening peak period based on field measurements obtained with a handheld portable particle counter and indigo disulfonate spectrophotometry. Statistical analysis showed that the passengers experienced poor air quality within the confines of the bus due to the poor air quality outside. Furthermore, the level of passenger comfort was dissatisfactory because of the high temperature, thereby highlighting the urgent need to improve the current situation. Numerical simulations were conducted using FLUENT software to explore the impacts of the air supply angle, the opening and closing of the bus door, and the chemical reaction between ozone and its precursors on the diffusion and distribution of ozone, the temperature, and the airflow field. The results indicated that high concentrations of ozone were present in the middle and front regions of the bus. Pollution can be reduced by keeping the bus door open for no longer than 20 s when waiting for other passengers, and the best optimization effect in relation to the temperature and passenger comfort was determined as an air supply angle of 30°. In addition, the average individual daily intake of ozone was combined with other relevant parameters to assess the exposure level. It is recommended that the elderly and children should avoid peak time travel to reduce their exposure to ozone (inhalation dose values > 60 µg/m3 and > 56 µg/m3 according to simulations, respectively). These findings are expected to effectively improve the air quality and passenger comfort levels in busses, thereby protecting the health of passengers and reducing carbon usage.

Correction to: Air quality and passenger comfort in an air-conditioned bus micro-environment.

The original version of this article unfortunately contained an error in the affiliation section and an error of the email address of corresponding author.

Air quality and passenger comfort in an air-conditioned bus micro-environment.

In this study, passenger comfort and the air pollution status of the micro-environmental conditions in an air-conditioned bus were investigated through questionnaires, field measurements, and a numerical simulation. As a subjective analysis, passengers' perceptions of indoor environmental quality and comfort levels were determined from questionnaires. As an objective analysis, a numerical simulation was conducted using a discrete phase model to determine the diffusion and distribution of pollutants, including particulate matter with a diameter < 10 µm (PM10), which were verified by experimental results. The results revealed poor air quality and dissatisfactory thermal comfort conditions in Jinan's air-conditioned bus system. To solve these problems, three scenarios (schemes A, B, C) were designed to alter the ventilation parameters. According to the results of an improved simulation of these scenarios, reducing or adding air outputs would shorten the time taken to reach steady-state conditions and weaken the airflow or lower the temperature in the cabin. The airflow pathway was closely related to the layout of the air conditioning. Scheme B lowered the temperature by 0.4 K and reduced the airflow by 0.01 m/s, while scheme C reduced the volume concentration of PM10 to 150 µg/m3. Changing the air supply angle could further improve the airflow and reduce the concentration of PM10. With regard to the perception of airflow and thermal comfort, the scheme with an airflow provided by a 60° nozzle was considered better, and the concentration of PM10 was reduced to 130 µg/m3.