Among the first impressions that a new visitor acquires of a city is often its ambient air quality. Polluted air is not just unsightly and uncomfortable to breathe. Inhaling polluted air can make a person sick and, in the extreme, lead to death. Air pollution also damages the natural and built environment. Because clean air improves both the health of the population and the quality of life in the city, national environmental protection authorities such as the United States Environmental Protection Agency (USEPA) as well as international organizations such as the World Health Organization (WHO) have established ambient air quality guidelines and legislation which prescribe standards to reduce the effects of air pollution on human health.

Maintaining clean air quality so that residents enjoy a healthy and pleasant living environment has been a priority for the Singapore Government. As a result, the air quality in Singapore compares favourably with that in other major cities, despite the presence of industrial centres within the city state. However, this achievement did not come easily. As a small urbanized city state, Singapore finds maintaining clean air quality a challenge, especially in view of its many constraints. These include its dense population, limited land and airspace, and vulnerability to transboundary pollution.

In addition, there are many trade-offs to be considered, and difficult choices to be made. While emissions from industries can potentially cause the air quality to deteriorate, these developments contribute significantly to the economic growth of the nation.