Why are age and mileage important factors in emissions testing?

Age and mileage are important factors in emissions testing primarily because older vehicles typically feature less advanced emissions control technology and are often not maintained as well as newer models. Over time, the effectiveness of emissions systems can deteriorate due to wear and tear, leading to increased exhaust emissions.

Older vehicles generally lack the sophisticated systems such as catalytic converters and onboard diagnostics that are common in newer models. As a result, they may have higher levels of harmful pollutants like nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) when emissions tests are conducted. Additionally, high mileage can correlate with increased engine wear and potential leaks or inefficiencies in the emissions systems, contributing further to heightened emissions levels.

In contrast, newer vehicles typically incorporate advanced technologies designed to meet stricter emissions regulations, resulting in lower emissions outputs. Therefore, understanding the relationship between the age and mileage of a vehicle and its emissions performance is crucial for effective emissions testing.