Aldehydes are compounds with a terminal carbonyl (HC=O) moiety, and are either unsaturated, that is, containing one or more carbon–carbon double bonds, or saturated. This structural difference has great significance for chemical reactivity as unsaturated aldehydes are two to three orders of magnitude more reactive than saturated aldehydes of similar carbon length. Nonetheless, aldehydes, in general, are ubiquitous components of the environment and their increased abundance is associated with increased risk of cardiovascular disease in humans. However, aldehyde abundance in the environment does not always spell doom because many familiar foods contain a variety of non-toxic aldehydes that in addition to providing flavor to foods (e.g., anisealdehyde, benzaldehyde, cinnamaldehyde, citral aldehyde) and beverages (e.g., anisealdehyde) are almost certain to stimulate beneficial actions systemically in humans, such as the anti-inflammatory activity of cinnamaldehyde. Yet these naturally derived aldehydes are to some extent in ‘competition’ with aldehydes generated in foods during the cooking/heating process, and some of which, in addition to their odor/flavor enhancing qualities (e.g., acrolein, formaldehyde), could very well be detrimental to the health of the consumer. Similarly, respirable air is teeming with aldehydes generated during organic combustion – for example, airplane exhaust, automobile exhaust, cigarette smoke, forest fire smoke, power plant emissions, and so on – resulting in quantitative enhancement of saturated and unsaturated aldehyde levels in the air, including acrolein, a-ethylacrolein, formaldehyde, crotonaldehyde and many others. Some of these aldehydes are difficult to measure accurately and can change in chemical structure over time due to chemical interactions in the air (e.g., ozone) and through complex photo-dependent processes, and thus, result in new potentially dangerous compounds as well.