The World Bank

The World Bank

Monitoring - Pollution Prevention Guidelines


Courtesy of The World Bank


Pollution Prevention Guidelines to provide technical advice and guidance to staff and consultants involved in pollution-related projects. The guidelines represent state-of-the-art thinking on how to reduce pollution emissions from the production process. In many cases, the guidelines provide numerical targets for reducing pollution, as well as maximum emissions levels that are normally achievable through a combination of cleaner production and end-of-pipe treatment. The guidelines are designed to protect human health; reduce mass loadings to the environment; draw on commercially proven technologies; be cost-effective; follow current regulatory trends; and promote good industrial practices, which offer greater productivity and increased energy efficiency.

Table of Contents

  • Objectives
  • Quality Assurance and Quality Control
  • References and Sources


Pollutants of concern for the environment must be monitored to obtain reliable information on the quality of ambient air and media. Such information is a necessary part of any environmental management system, whether in the private or the public sector. It provides a basis for informed decisionmaking and the development of environmental management strategies. To ensure that decisions are made on a sound basis, it is essential to be confident that the measurements reflect the existing situation; in other words, the data must be of clearly defined and documented quality.

Hence, quality assurance and quality control are important. The way in which samples are taken and analyzed is as important as the results of the measurement (analysis) itself. A quality assurance system should include institutional as well as technical aspects. Environmental releases from major industrial sources are monitored as part of the overall monitoring of sources of the pollutants of concern within an airshed or water basin. The objectives of monitoring systems also include process optimization, auditing, and compliance with regulatory requirements such as emissions standards.


Monitoring plans are designed and implemented for collecting data on ambient air and water quality and on releases of pollutants of concern from major point sources. The elements of a monitoring plan normally include selection of the parameters of concern; the method of collection and handling of samples (specifying the location, the frequency, type, and quantity of samples, and sampling equipment); sample analysis (or, alter- Monitoring natively, on-line monitoring); and a format for reporting the results.

Ambient levels of pollutants such as heavy metals are measured in air, water, and soil, along with other parameters, at specified locations and frequencies and using specified equipment and methods. The objective is to collect and analyze representative samples to produce data for use in the environmental management system. To ensure acceptable ambient levels, concentrations of pollutants in the environment are predicted, using models and information on emissions from some of the major pollution sources, and are then monitored (that is, verified by actual observation). Corrective action, follows, when necessary.

Ambient Air Quality

Although, in theory, all pollutants should be monitored, in practice, only the significant pollutants are monitored, at best. Usually, monitoring is limited to some key pollutants such as suspended particulate matter (SPM). A good air quality management system usually reviews the probable emissions sources and the environmental receptors in the area of concern and then selects the pollutants to be monitored. One such pollutant is particulate matter of less than 10 microns in aerodynamic diameter (PM10). (Some modern air quality monitoring systems are being developed to monitor PM2.5 and PM1, that is, particulates of sizes less than 2.5 microns and 1 micron, respectively.) Other pollutants normally monitored include sulfur oxides, ozone, and nitrogen oxides. In some places, other priority pollutants may be included in ambient air monitoring: examples are volatile organics such as benzene and vinyl chloride, polynuclear aromatic hydrocarbons (PAHs), dioxins, furans, asbestos, inorganics, and arsenic, cadmium, lead, mercury, nickel, and other heavy metals.

Locations of monitoring stations are determined on the basis of the receptors in the airshed. A network of monitoring stations is usually established to estimate the exposure levels. Normally, a monitoring station is also set up to measure background concentrations in cases where the resultant ambient levels of a particular source or sources are to be computed. The quality assurance plan should include the rationale for selecting the number and location of monitoring stations, the monitoring frequency, the equipment, and the method of sample collection.

Monitoring may be continuous or may be done for short durations of, say, 1 hour, 8 hours, or 24 hours to determine the maximum and average for the set period. Table 1 presents examples of the common ambient air monitoring systems used for some pollutants of concern.

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