Outdoor and indoor factors influencing particulate matter and carbon dioxide levels in naturally ventilated urban homes.

The present study investigated indoor and outdoor concentrations of two particulate matter size fractions (PM and PM) and CO in 20 urban homes ventilated naturally and located in one congested residential and commercial area in the city of Alexandria, Egypt. The results indicate that the daily mean PM concentrations measured in the ambient air, living rooms, and kitchens of all sampling sites exceeded the WHO guideline by 100%, 65%, and 95%, respectively. The daily mean outdoor and indoor PM levels in all sampling sites were found to exceed the WHO guideline by 100% and 80%, respectively. The indoor PM and PM concentrations were significantly correlated with their corresponding outdoor levels, as natural ventilation through opening doors and windows allowed direct transfer of outdoor airborne particles into the indoor air. Most of the kitchens investigated had higher indoor concentrations of PM and CO than in living rooms. The elevated levels of PM and CO in domestic kitchens were probably related to inadequate ventilation. The current study attempted to understand the sources and the various indoor and outdoor factors that affect indoor PM, PM and CO concentrations. Several domestic activities, such as smoking, cooking, and cleaning, were found to constitute important sources of indoor air pollution. The indoor pollution caused by PM was also found to be more serious in the domestic kitchens than in the living rooms and the results suggest that exposure to PM is high and highlights the need for more effective control measures. : Indoor air pollution is a complex problem that involves many determinant factors. Understanding the relationships and the influence of various indoor and outdoor factors on indoor air quality is very important to prioritize control measures and mitigation action plans. There is currently a lack of research studies in Egypt to investigate determinant factors controlling indoor air quality for urban homes. The present study characterizes the indoor and outdoor concentrations of PM, PM, and CO in residential buildings in Alexandria city. The study also determines the indoor and outdoor factors which influence the indoor PM and CO concentrations as well as it evaluates the potential indoor sources in the selected homes. This research will help in the development of future indoor air quality standards for Egypt.