Which of the following factors contributes to respiratory irritation?

Ozone is a significant contributor to respiratory irritation due to its chemical composition and the way it interacts with the respiratory system. Ozone is a strong oxidant and can lead to inflammation of the airways, reducing lung function, and exacerbating conditions such as asthma and chronic obstructive pulmonary disease (COPD). When inhaled, ozone can cause irritation and swelling in the throat and lungs, leading to symptoms like coughing, chest pain, and shortness of breath. Additionally, ozone exposure has been linked to increased susceptibility to respiratory infections and higher risks of respiratory-related mortality.

While other factors listed can also be harmful to respiratory health, ozone's unique properties as an oxidant make it particularly effective at causing direct irritation to the respiratory tract. High humidity can affect comfort and respiratory function but is not a direct irritant like ozone. Particulates can contribute to respiratory issues, but their effects are generally more related to long-term exposure rather than acute irritation. Nitrogen oxides are pollutants that can lead to respiratory problems, but they typically don't cause irritation to the same degree as ozone does on a molecular level.