Application of Biomarkers in Assessing Human Health Impacts of Air Pollution

Air pollution causes a huge number of fatalities every year around the world. It has been suggested that air pollution contributes to approximately 8.8 million extra deaths worldwide every year, and about 40–80% of these deaths have been linked to various cardiovascular diseases (CVD). Recent epidemiological studies have provided extensive evidence linking air pollution with a wide variety of adverse health conditions and diseases pertaining to respiratory and cardiovascular systems, especially among vulnerable demographic groups such as the children, the elderly, and those with preexisting compromised cardiopulmonary conditions such as asthma. These adverse effects predominantly include reduced functionality of the lung, chronic respiratory and cardiovascular inflammation, chronic obstructive pulmonary disease (COPD), stroke and heart attacks, and lung cancer. All these effects have been associated with exposure to at least one major air pollutant that is routinely found in the ambient air in large cities around the world. These air pollutants include suspended particulate matter (PM), ozone (O3), nitrogen oxides (NOx), sulphur dioxide (SO2), carbon monoxide (CO), volatile organic carbon compounds including polyaromatic hydrocarbons (PAHs), and trace metals such as lead (Pb) (Cohen et al. 2017). Although each of these air pollutants can induce serious health implications for humans, exposure to fine (diameter ≤ 2.5 μm) and ultrafine (diameter ≤ 0.1 μm) particles are believed to be the leading cause of cardiorespiratory illnesses in the developing world. However, the current understanding of the health effects of PM is limited, and most of the epidemiological evidence of linking adverse health effects to PM exposure is not conclusive. Moreover, the cellular and molecular mechanisms by which PM, exclusively and in mixture with other air pollutants, elicit toxic effects in humans are yet to be fully understood. Nevertheless, the use of conventional biochemical and novel molecular biomarker assessments can provide important insights into the cellular perturbations that lead to the onset of adverse health effects during chronic exposure to air pollutants. Furthermore, the advent of next generation, systems biology molecular techniques (e.g., omics technologies) provides exciting new avenues to study the effects of air pollution on human health. These new tools can provide new knowledge on the interactions of air pollutants with genes, proteins and other biomolecules that are currently unknown, and thus, develop a more holistic and in-depth mechanistic understanding of the toxicity of these pollutants. Ultimately, this advanced understanding can then be used to develop toxicity models that can predict potential future adverse health outcomes early during exposure, enabling preventive interactions and implementation of effective mitigation strategies.