Outdoor-indoor air quality in Riyadh: SO2, NH3, and HCHO.

A funded research project was conducted during the period July 1992 through November 1994. The project was designed to evaluate indoor and ambient air quality in and around buildings of different types and uses in Riyadh, the capital of Saudi Arabia. Thirty intercity buildings and two outercity (background) sites were carefully selected and monitored for air quality. Ten air pollutants, together with relevant meteorological parameters, were monitored indoor and outdoor at each site continuously and simultaneously for a period of two weeks covering summer and winter seasons. This article discusses the results obtained for sulfur dioxide (SO2), ammonia (NH3) and formaldehyde (HCHO). Results of this investigation revealed that most sites had on the average exceeded the recommended standards for SO2 and NH3 both indoor and outdoor, with indoor levels being worse than outdoor during winter time. Several sites also showed high levels of HCHO, with outdoor levels being consistently higher than indoor. Statistical and frequency analyses were performed on the collected data, showing seasonal and sector by sector variability, and outdoor-indoor correlations.