Relationship between Annual Average Concentration of Ambient PM10 and Out-patients with Respiratory Disease: Thailand Case Study

Abstract

The objectives of this research were to identify (1) correlation between annual average concentration of ambient PM₁₀ and prevalence of out-patients with respiratory diseases; (2) the relative risk and attributable proportion of out-patients with respiratory disease due to long-term exposure to ambient PM₁₀; and (3) the correlation between annual average concentration of ambient PM₁₀ and the relative risk of out-patients with respiratory disease. Time-series data of annual average concentration of ambient PM₁₀ and prevalence rate of out-patients with respiratory disease during an 11- year period (2004-2014) in the study area were obtained from the Pollution Control Department, Ministry of Natural Resources and Environment, and the Bureau of Policy and Strategy, Ministry of Public Health, respectively. To estimate the relationship, Pearson’s product moment correlations between variables were calculated and significance testing of correlation coefficients were carried out. A retrospective cohort method was used to study the annual average concentration of ambient PM₁₀ ratio, the relative risk and the attributable proportion. No association was found between the annual average concentration of ambient PM₁₀ and the prevalence rate of out-patients with respiratory disease; however, there was a highly significant positive relationship between the annual average concentration of ambient PM₁₀ ratio and the relative risk of out-patients with respiratory disease (r = 0.852, df = 4, p < 0.05). The relative risk of out-patients with respiratory disease due to exposure to the annual average concentration of ambient PM₁₀ equal to or higher than 30 µg/m³ varied within the range of 0.99 - 1.14, and the attributable proportion of out-patients with respiratory disease were about 10 % and 3 % attributed to exposure to the annual average concentration of ambient PM₁₀ higher than 30 µg m^-3 and 40 µg m^-3, respectively.