In 2014, the World Health Organization announced that India’s cities were among the most polluted in the world. Mobile sources are major contributors to local air pollution due to the emissions from combustion. Aggressive measures have been planned to control emissions from on-road motor vehicles. They include a clear roadmap toward ultra low-sulfur fuel and filter-forcing Bharat Stage VI (BS VI) emission standards, which ensure that all new on-road diesel engines are equipped with the latest emission control technologies, including diesel particulate filters (DPFs), to maximally reduce tailpipe emissions.
However, limited attention has been paid to non-road (land-based) mobile sources, even though the majority of them are powered by diesel engines. These engines usually emit much higher unit pollutants than on-road engines, due to less stringent regulation and enforcement. This raises concerns about their potential emissions, including fine particulate matter with a diameter of 2.5 micrometers or less (PM2.5) and nitrogen oxides (NOx), considering the rapidly growing market. These engines increase the chances of the public being exposed to high levels of pollution, leading to deteriorating health conditions in India. To adequately control those sources, it is necessary to understand their market characteristics and the development of their emissions inventory.
This study looks into two key types of non-road mobile sources: agricultural tractors and construction equipment. Agricultural tractors are widely used in rural areas, and often operate beyond their designated tasks, serving as alternative transportation for passengers and goods. Most construction equipment is used in or near India’s urban centers, where population density is high and air quality is typically poor. Both agricultural tractors and construction equipment use limited emission control technology. As a result, emissions from their diesel engines are expected to be significant, and will potentially have strong negative impacts on local air quality and health in India. Therefore, this preliminary study intends to shed some light on non-road emissions in India and to call for more attention and action.