By emissions of carbon dioxide Fireworks contributes to the greenhouse effect.
Fireworks also causes acid rain: is a matter of sulfur dioxide into the atmosphere.
There are also heavy metals (lead and zinc) into surface water, soil and sewage sludge.
Fireworks also caused a concentration of tiny particles in the air (smog): there is no point in the year when the air is so polluted as on January 1, between midnight and one o'clock. In people with a disease of the airways or with cardiovascular disease, this can lead to acute symptoms. Fireworks consists of 75% of potassium nitrate (KNO3), and for the rest carbon (15%) and sulfur (10%). The combustion is caused by a combination of a fuel (C and S), and oxygen from potassium nitrate. LINK firework in Rotterdam