Assessment of NOx Levels in an Underground Hospital Car Park: Implications for Occupational and Environmental Health

Abstract

Environmental air pollution poses a significant threat to human health, with nitrogen oxides (NOx) identified as contributors to respiratory and cardiovascular diseases. This study evaluates NOx levels in an underground car park of a hospital complex, where vulnerable patients frequently visit. NOx levels were assessed using direct-reading devices with high-resolution electrochemical sensors measuring NO and NO2 concentrations. Measurements consistently remained below the legal occupational exposure limit values for car park employees, averaging around 10% of the limit. However, approximately 75% of days recorded NO2 concentrations exceeding 70% of the World Health Organization’s (WHO) recommendations, with about 20% surpassing the 0.1 ppm limit set by the WHO. The highest recorded one-hour NO2 level reached 0.165 ppm, typically around 11:00 h. The study recommends that vulnerable patients, especially asthmatics, utilize outdoor parking, while all users should avoid using the car park as a waiting area. Employees are advised to spend more time in enclosed spaces with fresh air. Although occupational levels are generally within limits, environmental levels during peak hours could pose risks to vulnerable populations. Mitigation measures, such as increased ventilation during peak hours and restricted access based on emission levels, are suggested to minimize exposure and protect public health.