Which gas is a significant product of combustion that can be hazardous to health?

Carbon dioxide is a significant product of combustion that poses health hazards, particularly in high concentrations. During the combustion of organic materials, carbon combines with oxygen to form carbon dioxide. While carbon dioxide is not toxic at normal atmospheric levels, elevated concentrations can lead to harmful effects, including headaches, dizziness, confusion, and in extreme cases, unconsciousness or death due to displacement of oxygen in the air.

Understanding the impact of carbon dioxide is crucial, especially in confined spaces where ventilation is limited, as the risk of accumulation increases significantly. This is particularly relevant in fire situations, where combustion can quickly raise carbon dioxide levels.

In contrast, the other gases listed have different implications. Hydrogen, while flammable, is not a primary product of combustion in typical scenarios involving organic materials. Nitrogen is abundant in the atmosphere and does not contribute to health hazards directly; it's relatively inert and does not participate in combustion in a way that would pose immediate danger. Ozone is a byproduct of some combustion processes, especially in atmospheric reactions, but it typically exists at higher levels in the atmosphere as a pollutant and can be harmful at ground level. However, it is not a direct product of combustion from most materials, limiting its relevance to this question about hazardous combustion products.