Health risk associated with air pollution and its exposure has gained much importance in the recent years. The potential toxicity of air pollutants especially particulate matter (PM) is attributed to its chemical composition and size. Hence, it is imperative to understand the morphology, size, and chemical composition of PM for health risk assessment. Polyaromatic hydrocarbons (PAHs) present in PM have high toxicity and mutagenic potential. Recent advancement in technology such as bioassays for cytotoxicity, oxidative stress, and apoptosis studies using human cell lines has allowed us to comprehend the underlying mechanism of particle toxicity and its impact on human health. This chapter deals with the health risks associated with air pollution and exposure assessment with a focus on chemical toxicity associated with air pollutants, especially PM. Health risks associated with particle-bound chemical compounds in school children are also explained in this chapter.