Common airborne irritants or allergens such as dust, mold spores, some odors, pet allergens and pollen.Particulate Matter (PM) PM2.5. These are the sort of particles you find in coal dust from power stations, diesel exhaust fumes, factory emissions and from construction works.Gas based air pollution, including odors such as Volatile Organic Compounds (VOCs), Ozone, Benzathine, and Formaldehyde. These particulates you can find in petrol fumes, chemical emissions and from many industrial processes.