PM2.5 refers to particles with 2.5um in diameters or smaller, also called as inhalable coarse particles. It mainly comes from daily power generation, industry manufacturing, and automobile exhausts, which always contains Cu, Ni, Zn, Pb, Mn, Cr, Fe, Co, Cd and some volatile substances. Human could inhale these particles through bronchus to lung and finally dissolve in the blood. With accumulation of these heavy metals in the body, a serious physiological function including inhalation, angiocarpy and nerve are affected. A statistics from WHO showed that in Europe, PM2.5 tolled 386000 people every year, shortening 8.6 months Life expectancy.
How to collect PM2.5 sample and test the concentration
There are 3 ways to test PM2.5, gravimetric method,Microoscillating balance method and β-ray spectrometry. In China, gravimetric method is adopted. A series of sampling apparatuses are used to collect a certain volume of air and keep the PM 2.5 and PM 10 on known-weight filter membrane; then calculate the mass difference and volume difference to get PM 2.5 concentration.
How to test heavy metal content in PM2.5
For example of Beijing area, the organic content in PM 2.5 has risenfrom 20%-30% to 30%-40%. To test the major metal elements such as Pb，Cu，Fe，Cr，Ni，Cd，Zn, a thorough pretreatment of the membrane is a must. Microwave digestion is indisputably a very efficient pretreatment measure. It could process several samples per batch and guarantee the total digestion of all target elements with good accuracy and parallelism, also very user friendly.