Air pollution has become a major issue in cities due to urbanization, population growth, industrial development, and increasing number of vehicles. The study used Gmelina arborea tree leaves as a bioindicator to determine the Air Pollution Tolerance Index (APTI) as a simple and effective compositional index of environmental health in three cities in the Caraga Region, Philippines. To calculate the APTI, four biochemical parameters of tree leaves were calculated: relative water content, total chlorophyll content, leaf-extract pH, and ascorbic acid content. In terms of the APTI category, results showed that all G. arborea species collected in all sample sites are classified as sensitive to air pollution, with the sample collected in Bayugan City being the most sensitive, with an APTI value of 7.66, and the samples collected in Butuan and Cabadbaran City being the least sensitive, with APTI values of 9.54 and 9.11, respectively. A Kruskal-Wallis test revealed a significant difference between the APTI values of G. arborea trees in the three sampling areas in the Caraga region. Based on the APTI computed values of the tree leaves determined in all sites, it is concluded that G. arborea species can be used as a bioindicator of air pollution, classified as sensitive.

Air is an important medium for all living beings and is essential for the well-being of all. Monitoring of air is important to know the quality of air. The air quality monitoring was carried out in Kolhapur City under the National Air Monitoring Program. The present study involves the assessment of PM10 as described in the National Ambient Air Quality Standards (NAAQS). The source apportionment study related to particulate matter was carried out in Kolhapur City. The study also determined the average PM10 concentration in the city as it will be useful for preparing an action plan to reduce PM10 concentration. PM10 concentration was calculated as per the standard method adopted by CPCB. Sampling was carried out for 8 hours in three shifts twice a week at each sampling site for three consecutive years. Mahadwar Road (MR) and Dabholkar Corner (DC) were selected per the surrounding residential area, population density, and traffic conjunction. The third site Shivaji University (SUK), was selected as a control site. The results indicated that the PM10 level has risen above the prescribed standards of NAAQS. The reason for the rise in PM10 may be due to fossil fuel burning, construction activity, vehicles, and unpaved roads. The Analysis of Variance (ANOVA) technique is used to check the equality of the mean concentration of PM10 at these three locations and found a significant difference between mean concentrations of PM10, suggesting increased particulate matter.