Air quality and health risks in chemical supply shops in southeastern Nigeria

Abstract

This study assessed the concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and hydrogen sulfide (H₂S) in chemical stores at Ogbete Market, Enugu, and Ogbo-ogwu Market, Onitsha, southeastern Nigeria, during the wet season (June to August 2024). Air quality measurements, taken from six randomly selected stores in each market and a control site (clothing store) located at about 900 m away, revealed that while concentrations of SO₂ and NO₂ far exceeded public health guidelines (WHO), they remained below Occupational Safety and Health Administration (OSHA) limits. However, chronic low-level exposure, even within OSHA limits, can still lead to respiratory symptoms and reduced work productivity over time, especially in poorly ventilated indoor shops. Sampling was conducted at a height of 2 m above ground to reflect the breathing zone of an average adult, with data collected during morning and afternoon sessions to capture fluctuations in market activity. Using the Aeroqual Series 300 gas monitor, real-time results indicated hazardous conditions in many stores, and exposure factor–adjusted air concentrations (EF-AACs) were calculated to assess actual exposure scenarios. Hazard quotients (HQs) for each pollutant showed a concerning risk of respiratory diseases, particularly from SO₂ and NO₂ exposure, with multiple stores exhibiting HQ values greater than 1. The findings highlight the urgent need for improved ventilation and stricter regulations in these markets, while also contributing to the limited research on air quality in commercial environments in Nigeria. This study lays the foundation for future interventions aimed at protecting the health of workers in informal markets, advancing public health initiatives in regions with underdeveloped regulatory frameworks.