AN ASSOCIATION BETWEEN INCENSE SMOKE EXPOSURE AND INCREASED CAROTID INTIMA-MEDIA THICKNESS AMONG PEOPLE LIVING IN MUEANG DISTRICT, SAKON NAKHON PROVINCE: A COHORT STUDY

Abstract

Incense burning, a source of household indoor air pollution, is possible to effect on cardiovascular system. This study sought to examine the association of exposure to household incense smoke with increased Carotid intima-media thickness (CIMT) amongst people living in the central city of Sakon Nakhon province, Thailand. A one-year cohort study was conducted between July 2016 and September 2017. There were 132 participants at baseline and remained 100 participants after 1-year follow-up. Participants were stratified into three groups by frequentcy of incense use in their household; non-exposed group, non-daily exposed group, and daily exposed group. All participants were interviewed by questionnaire and underwent a clinical assessment, blood test and a carotid artery ultrasound. Household PM10 concentrations, temperature, and relative humidity (RH) were measured inside all of the participants’ home during the wet and the dry seasons. To find an association, multivariate analysis was performed with adjusted some potential confounding factors. The result showed the positive association between household burned incense and CIMT at common carotid artery (CCA) and left of common carotid artery (LCCA) but, not found in the CIMT of right of common carotid artery (RCCA) at baseline. After 1-year follow-up, the progression of CIMT in incense smoke exposure group were not found an association. For the average of PM10 concentrations inside house was 24.2±11.4 µg/m3. An increasing of 1 µg/m3 average indoor PM10 concentration were significant (p<0.05) associated with 8% increased risk of increased mean CCA (AOR = 1.08; 95%CI 1.01 - 1.15), 7% increased risk of increased maximum CCA (AOR = 1.07; 95%CI 1.01 - 1.12) and 3% increased risk of increased maximum LCCA (AOR = 1.03; 95%CI 1.01 - 1.09) but not for CIMT at RCCA. In conclusion, long-term exposure to incense smoke was associated with an increased CIMT. However, the progression of CIMT after a year of follow-up was not associated with incense smoke exposure but was associated with household particulate matter (PM10). Therefore, the policy for environmental health should be considered to provide the standard level of indoor/ residential air quality in Thailand.