Due to its affinity with hemoglobin in the blood system is stronger than the oxygen, the carbon monoxide will compete with oxygen for binding sites in hemoglobin. Thus, the toxic effect of carbon monoxide to human and animals is the result of oxygen depletion in the blood system. Ozone is a secondary pollutant formed through the series reactions of nitrogen oxides and active hydrocarbons under the sunlight. Due to its strong oxidative reactions, ozone can cause irritating effects on respiratory system such as coughing, asthma, headache, tired, and even lung damage. Children, elder people, patients, or person with active outdoor activities are most vulnerable to ozone damage.
Ozone can also cause damage to crops, painting, and plastic products such as tires.
In addition to the natural occurrences of hydrocarbons, the major sources of hydrocarbon come from incomplete combustion and evaporation or leakage of gasoline products. There are two groups of Hydrocarbons, i.e., methane and non-methane hydrocarbons. The majorities of methane come from natural biological activities and are not involved in photochemical reactions. The non-methane hydrocarbons mainly come from human activities and most of these compounds are involved in photochemical reactions. The location of air monitoring stations will also influence the probe height and should be considered when placing the probe.