| Category | Components | Characterization | Health and environmental impacts |
| Particles | PM | Complex mixtures of EC, OC and inorganic ash; 70% - 90% of PM is PM2.5; can be transported over long distances. | Act as vehicles to carry absorbed hazardous compounds into the respiratory tract; increases respiratory and cardiovascular mortality and morbidity, including asthma and emphysema; contributes to regional haze and impair visibility. |
| EC | Primary particles; 2% - 20% of PM mass. | Scatters and absorbs solar radiation, thus affecting climate. | |
| OC | Primary or secondary particles; 60% - 70% of PM mass. | Some are carcinogens or irritants. | |
| Trace elements | Concentrate in the fine particles. | Some metal elements are toxic. | |
| VOCs | Acrolein | Can be adsorbed on particles. | An organic irritant and a potent lachrymatory agent. |
| Formaldehyde | Can be adsorbed on particles. | An organic irritant and a carcinogen linked to nasal and throat cancer and leukemia. | |
| Isocyanic acid | Found in both cigarette smoke and vegetation fire smoke. | Contribute to cardiovascular problems and inflammation. | |
| SVOCs | PAHs | Specific species varies with composition of vegetation; condense or adsorbed onto fine particles or as volatiles in the vapor phase. | Carcinogenic and mutagenic. |
| Permanent gases | CO2 | Dependent on availability of O2. | Greenhouse gas |
| CO | Dependent on availability of O2; abundant only in immediate vicinity of fire. | Toxicity due to reducing oxygen-carrying capacity of the blood, known as hypoxia. | |
| CH4 | Global warming potential 21 times higher than CO2. | Greenhouse gas | |
| NOx | Reactive; concentrations change with distance from fire. | Irritant and precursors of O3. | |
|
| Water vapor | Can condense onto fine particles. | Contributes to regional haze and impairs visibility. |
| Secondary products | O3 | Secondary product of NOx, VOCs and CO; can be transported over long distances. | Causes chest pain and respiratory problems. |