Table 2.

Redox mechanisms of air pollutants and cardiopulmonary diseases.

Pollutant	Mechanisms	Physiological outcomes	Reference
PM2.5, PM10, & PM0.1 (UFPs)	Enters bloodstream Promotion of atherosclerotic progression Oxidative stress Acute conduit artery vasoconstriction	Increased presence of hypertension, blood coagulation, and reactive hyperemia Increased risk for exacerbations of congestive heart failure and respiratory diseases	Briet et al. (2007) Brook et al. (2004) California Air Resources Board. (2020) Gold et al. (2000) Lucking et al. (2008) Morawska et al. (2008) Mutlu et al. (2007) Peters et al. (2001) Suwa et al. (2002) Wellenius et al. (2005)
NO2 and other NOx	Oxidative Stress ROS production causing lung tissue damage Inflammation Disrupts endothelial function	Exacerbation of respiratory diseases (e.g. COPD) Trigger/aggravator of cardiovascular conditions (e.g. acute coronary episodes, arrhythmia)	Briet et al. (2007) Brook et al. (2004) Peters et al. (2001)
O3	Airway inflammation Disrupts endothelial function Oxidative stress Acute conduit artery vasoconstriction	Increased presence of hypertension and blood packet activation, increasing risk for CVD Aggravates CVD (e.g. coronary artery disease, stroke)	Briet et al. (2007) Rajagopalan et al. (2018)
CO	Body cell and tissue hypoxia by binding to hemoglobin Disrupts endothelial function	Damage to heart and lung tissue Worsens respiratory and cardiac function Increased embolisms and thrombotic changes	Blumenthal (2001) Briet et al. (2007) Hoek et al. (2001)
SO2	Oxidative stress Produced sulfuric acid causes irritation to eyes, mucous membranes, and skin	Disrupts respiratory function and exacerbates pre-existing respiratory conditions Increased morbidity and mortality of CVD (heart failure, arrythmia) Increased hypertension and thrombotic events	Hoek et al. (2001) Ibald-Mulli et al. (2001) Lipsett (2001)
VOC	May combine to form harmful pollutants (tropospheric ozone and smog) May increase CRP plasma levels	Damage to heart and lung tissue Worsens respiratory and cardiac function Increased embolisms and thrombotic changes	Pankow et al. (2003) U.S. Environmental Protection Agency (2014)

Only the most representative citations are given. (PM, particulate matter; PM_2.5, particles with a diameter ≤ 2.5 μm; PM₁₀, particles with a diameter ≤ 10 μm; PM_0.1, particles with a diameter ≤ 2.5 μm; NO₂, nitrogen dioxide; NO_x, nitrogen oxides; O₃, ozone; CO, carbon monoxide; SO₂, sulfur dioxide; VOC, volatile organic compounds; μg/m³, micrograms per meter cubed; ppm, parts per million; CVD, cardiovascular disease; ROS, reactive oxygen species; CRP, C-reactive protein.)