A study of adults with asthma and chronic obstructive pulmonary disease (COPD) found that individuals with lower levels of some antioxidants in their blood were more vulnerable to the harmful effects of air pollution.  Particulate matter (PM) – the main pollutant measured in this study – is produced by traffic and combustion of fossil fuels. PM less than 10 micrometers in diameter, or PM10, is known to exacerbate respiratory illness and increase the risk of heart attacks and other cardiovascular disease. One way air pollutants can harm health is through oxidative stress. Harmful oxidant molecules can form when air pollutants are absorbed through the lungs. These oxidants also called free radicals damage cells. The body constantly tries to counteract oxidant molecules with protective ones (antioxidant). If not enough anti-oxidant molecules are available to cancel them out, oxidative stress  may occur.

In this study, researchers wanted to see if individual levels of antioxidants and related genetic markers would protect against harm from oxidative stress imposed by particulate air pollution. Results showed participants with low levels of vitamin C in their blood were more vulnerable to PM10. The study is important as it indicates that a healthy diet including fruits and vegetables may protect against the common health threat of air pollution.