Overview

As mentioned in Chapters 4, 5 and 16 chemicals can be a nuisance or pose safety, health and environmental risks, or become wasteful of expensive resources if allowed to escape excessively and uncontrollably into the general or workplace environment. Escapes can result from inadequate process control, errors in operation or maintenance, incomplete understanding of the process, etc. Such problems can arise from both: periodic emissions of chemicals due to the need to open, or enter, the 'system' occasionally (e.g. during sampling, cleaning, line-breaking) including both planned and unplanned releases (e.g. due to accidents, human error) and, continuous low-level fugitive emissions from normally-closed points, e.g. valve seals, flange gaskets, pump seals, drain valves.

The need to monitor the impact of activities involving chemicals on the environment may stem from sound management practice or to satisfy a host of specific legal requirements. Thus, in the UK under the Environmental Protection (Prescribed Substances and Processes) Regulations 1991, operators must apply BATNEEC to prevent or minimize the release of prescribed substances into the environment, or to render harmless any emissions. The prescribed substances for release into the air are given in Table 10.1. No prescribed process may be operated without an authorization from the Environment Agency and air pollutants which must be measured and the frequency of monitoring are set out in the authorization. Compliance with emission limits for municipal waste incineration plants (Table 10.2) also requires monitoring.