external costs and external benefits of business decisions

What are External Costs?

External costs are costs that a business imposes on people or the environment that are not reflected in the price of its product. Think of a factory that releases smoke into the air. The factory pays for its machinery, but the nearby residents suffer from poor air quality – that’s an external cost.

• Pollution that harms local wildlife
• Noise that disturbs neighbours
• Traffic congestion caused by delivery trucks

Mathematically we can write the total cost as: $$C_{\text{total}} = C_{\text{internal}} + C_{\text{external}}$$

What are External Benefits?

External benefits are benefits that a business provides to others that are not captured in the price of its product. Imagine a company that builds a new park in a town. The park is free for everyone to use, so the community enjoys recreation and cleaner air – that’s an external benefit.

1. Improved public health from green spaces
2. Increased property values nearby
3. Enhanced community pride and cohesion

We can express it as: $$B_{\text{total}} = B_{\text{internal}} + B_{\text{external}}$$

Analogy: The “Noisy Neighbor” Example

Imagine you live next to a neighbour who plays loud music all night. The noise is an external cost to you. If you decide to build a soundproof wall, you pay the cost, but you also improve your own living environment – that’s an internal benefit. The neighbour, however, might enjoy the music more, which could be considered an external benefit to the community if it encourages social gatherings.

Case Study: A Factory and the River

Exam Tip: How to Answer Questions on External Costs

When you see a question about external costs:

1. Define external cost in your own words.
2. Give at least one real‑world example (e.g., factory pollution).
3. Explain who bears the cost and why it is not included in the product price.
4. Use the symbol $C_{\text{external}}$ if you want to show the concept mathematically.

Remember: clarity and a concrete example will earn you full marks.

Exam Tip: How to Answer Questions on External Benefits

For external benefits:

1. Define external benefit clearly.
2. Provide an example such as a company building a public park.
3. Identify who benefits and why the benefit is not reflected in the product price.
4. Use the notation $B_{\text{external}}$ if you wish to show the concept mathematically.

Show that you understand the difference between internal and external effects.