Preliminary Study on Mercury and Lead in the Ambient Air of Metro Manila, the Philippines

Abstract

Despite being acknowledged as an air pollutant, heavy metal contaminants in the atmosphere are not yet well studied in the Philippines. This study aims to assess the particulate matter, as well as mercury and lead concentration, in Metro Manila's ambient atmosphere. A one-hour sampling period was used to collect data at seven sampling stations using a respirable dust sampler with a flow rate of 1.4 m3/min. The mercury concentration was determined using cold vapor atomic absorption spectroscopy, whereas lead concentrations were measured using flame atomic absorption spectroscopy. Taguig had the highest level of total suspended particulates (TSP) at 524.07 μg/NCM, followed by Caloocan (459.92 μg/NCM) and Quezon City (434.50 μg/ NCM). Parañaque reported moderate particulate levels – recorded at 298.95, 291.69, and 347.36 μg/NCM, respectively. Valenzuela had the lowest TSP level at 263.85 μg/NCM. Results show that mercury concentrations were highest in the City of Manila with 0.09 μg/m3, followed by Valenzuela City with 0.009 μg/m3, against the lowest concentration in Taguig City and Quezon City with 0.001 μg/m3. However, based on the legal airborne permissible exposure from the Philippine Occupational Safety and Health Standards, the mercury concentration in the seven cities of Metro Manila did not exceed its 0.5 mg/m3 (50 μg/m3) limit. Furthermore, results revealed that atmospheric lead concentration in Metro Manila existed only in trace amounts (≤ limit of detection). The high concentration of mercury in the City of Manila could be attributed to its high population density combined with massive industrial, commercial, and transport activities. Monitoring the concentration of heavy metals in the atmosphere is critical for the development of effective strategies for reducing the negative impacts of these global pollutants.