MEV 015: Unit 01 - Basic Concepts in Environmental Pollution

 CONCEPT OF STANDARDS AND GUIDELINES

The concepts of standards and guidelines play a crucial role in the field of environmental pollution control and management. When substances are present in the environment at such concentrations that they start causing harm to living beings or the ecosystem, they are termed as pollutants. To determine the harmful level of these substances, scientists study the dose-response relationship and identify the threshold value—the point beyond which the substance becomes harmful. These threshold values are then used to develop standards and guidelines.

Standards are legally enforceable limits for pollutants and are specific to each country. They define the maximum allowable concentration of a pollutant in the environment, and exceeding these limits can result in legal penalties. For instance, in India, the National Ambient Air Quality Standards (NAAQS) issued by the Ministry of Environment, Forest and Climate Change (MoEF&CC) prescribe that the annual average concentration of nitrogen dioxide (NO₂) in ambient air must not exceed 40 µg/m³ in residential, industrial, or rural areas. Any industry emitting NO₂ beyond this limit can face legal action. In India, bodies such as the MoEF&CC, the Central Pollution Control Board (CPCB), and the Bureau of Indian Standards (BIS) are responsible for developing and implementing these standards.

On the other hand, guidelines are non-binding recommendations that serve as reference points for developing national standards. They are not country-specific and do not carry legal force. Guidelines are generally issued by international organizations and aim to promote global health and environmental protection. For example, the World Health Organization (WHO) provides guidelines for acceptable levels of various air and water pollutants. Countries may refer to these guidelines while framing their own legally enforceable standards.

In summary, standards are legally binding and country-specific pollution limits based on scientific evaluation of pollutant effects, while guidelines are internationally accepted recommendations used to support the creation of such standards. Both work together to ensure environmental safety and public health.

Role of Source-Transport-Receptor (STR) System in Pollution Studies

In pollution studies, every pollution event can be understood by looking at three main parts: Source, Transport, and Receptor. This is known as the STR system.

The source is where the pollution starts. Identifying the source is very important for controlling pollution. When we know where the pollution is coming from, we can estimate how much pollution is being released. Some sources, like a factory chimney or a sewage pipe, are easy to find — these are called point sources. But some sources, like pesticides from farming fields or dirty water from many small homes, are spread out and harder to track — these are called non-point sources. Still, with proper planning and surveys, even non-point sources can be identified.

Once pollutants are released, they move or transport through the environment — through air, water, or soil. How they move depends on various natural conditions. In the air, movement of pollutants depends on things like wind speed, wind direction, temperature, and whether the area has mountains, valleys, or is near the sea. In water, it depends on how fast the water is moving, its temperature, etc. In soil, pollution can move sideways (lateral) or go deeper (downward) depending on soil conditions. While pollution is being transported, scientists monitor both the pollution levels and the conditions affecting their movement.

Finally, the receptor is what gets affected by the pollution. This can be humans, plants, animals, buildings, or even the economy. The goal of pollution control is to protect these receptors. To do this, we need to understand what kind of pollution it is and how it moves, so that we can create the right techniques to reduce its harmful effects.

Modern tools like environmental modelling help us understand how pollution moves from the source to the receptor. These models help us predict how much pollution will reach people or nature, and what can be done to stop it.

In short, the STR system helps scientists and environmentalists study, monitor, and control pollution more effectively by focusing on where it starts, how it moves, and who or what it harms.