Variation of indoor particulate matter concentrations and association with indoor/outdoor temperature : a case study in rural Limpopo, South Africa

There is still a pressing concern regarding the causes of poor indoor air quality and the consequent effects on health, because people spend a considerable amount of time indoors. Information about seasonal variation and the determinants of particulate matter (PM) concentrations could guide the design and implementation of intervention strategies. This study was conducted in Giyani, Limpopo province, South Africa. The main aim was to assess indoor air quality. Indoor PM and temperature were monitored to describe seasonal and diurnal patterns of indoor PM4 concentration and to estimate the association between PM concentrations and indoor as well as ambient conditions. Indoor PM4 was monitored hourly in kitchens for the duration of spring (September), summer (February) and winter (July). Indoor temperatures were monitored hourly in kitchens, living rooms and bedrooms. Outdoor temperature and outdoor relative humidity were also monitored for the same period. Indoor temperatures showed a large range in the three sampled seasons, with the maximum values raising the largest cause for concern. Maximum indoor temperatures in summer exceeded the threshold of 35 C, which has been shown to have adverse health effects. Occupants of the sampled households were exposed to indoor PM4 concentrations that exceeded national and international guidelines. Hourly indoor temperature was statistically significantly correlated to PM4 concentrations in the summer and spring (r = 0.22 and 0.24 respectively, p < 0.001 for both) and negatively correlated to outdoor relative humidity (r = 0.27, p < 0.001). Diurnal PM4 variations showed pronounced patterns with morning and evening peaks. PM4 was consistently higher throughout the day in summer compared to spring and winter. Community-based intervention strategies should consider these seasonal differences in PM4 exposure and tailor awareness messages for exposure prevention accordingly