Towards Developing an Indicator for Indoor Air Pollution in Nairobi Using Atmospheric Stability Indices

Abstract

The quality of indoor air inside offices, schools, other workplaces and homes is important not only for human comfort but also for their health. Poor indoor air quality (IAQ) has been tied to symptoms like headaches, fatigue, trouble concentrating, and irritation of the eyes, nose, throat and lungs. Also, some specific diseases have been linked to specific air contaminants or indoor environments, like asthma with damp indoor environments. Many factors affect IAQ. These factors include poor ventilation (lack of outside air), problems controlling temperatures, high or low humidity, recent remodeling, and other activities in or near a building that can affect the fresh air coming into the building. The quantification of IAQ is therefore necessary. Hourly data for CO and O3 and daily wind and temperature from Chiromo Environmental Monitoring station was used in this study. Stability Indices were obtained using the Hysplit Model. Time series analysis was used to obtaining the temporal variation of pollutants, meteorological variables and atmospheric stability. The relationship between pollutants, their interaction with meteorological variables and atmospheric stability was determined through correlation analysis. Minimum concentrations are observed between 0630hrs and 0730hrs and between 2030hrs and 2130hrs when highest concentrations are observed. During the early daylight and evening hours, pollutant concentration rises mainly due to the increase in traffic and acts as catalyst in the breakdown of O3. At midday (between 1300hrs and 1400hrs) maximum ozone concentrations are observed whereas CO depicts low level concentrations .During this period the atmosphere experienced a lot of conversion due to the thermal heating. Changes in day to day weather, is seen as a factor affecting the diurnal variation of indoor CO and O3 as weather determines how quickly pollutants are dispersed away from an area.