On the techniques and standards of particulate matter sampling

Air pollution and its limits are regulated by the environmental protection agency of an individual country according to their National Ambient Air Quality Standards (NAAQS). Particulate matter (e.g., TSP, PM10, and PM2.5) is one of the important criteria pollutants of NAAQS. Their measurement methods are specified in NAAQS, and detailed technical descriptions are given in standards. This review focuses on the sampling and analysis techniques and methods in the context of PM samplers' design mentioned in countries specific PM measuring standards (e.g., EPA Part 50, CEN 12341, IS 5182(23), etc.) and their comparison wherever is necessary. It discusses, different designs of PM samplers mentioned in standards and its important components, e.g., size fractionators cutoff efficiency, PM sampler head design, flow measurement, and calibration, and also addresses the important issues that are the limitation of present standards. Our review reveals that most of the country-specific standards show common practice in measuring PM2.5 using WINS impactor and VSCC cyclone as mentioned in EPA Part 50, except European Union (EU) standards, which has different design and parameters. For PM10 measurement, sampler design is different in EU and Indian standards than that of US EPA and other countries' standards, which is discussed in length here. All standards lack in pointing some inherent problems like change in D-50 cutoff of size fractionator of sampler under a high particle mass loading condition, which is common in countries like China and India. Other important issues where most of the standards lack include PM head design and specification, a key component of PM sampler on which the mass measurement results are largely dependent. Implications: The review paper discusses the air quality standards compliances of different countries and their comparisons. It focuses on the sampling and analysis techniques in context of PM samplers' design mentioned in countries specific PM measuring standards, and also addresses the important issues that are not mentioned in standards. Therefore, the discussions and findings of the review may be very useful while revising the existing air quality standards of different countries and to fill the research gap in this domain. Further, we have discussed several technical issues described in standards related to PM sampling which may be very helpful for PM sampler designing or modification in current designs as per the prevailing ambient conditions of a country.