Nitrogen Oxide (NO x )
What is it? Nitrogen oxide (NO, N 2 O, NO 2 and others) is produced by combustion of any type of fuel. NO 2 is a dark red gas with a pungent smell. It is one of the most dangerous air pollutants because it is highly harmful and, in favourable conditions, produces smog . Exhaust gases from vehicles are responsible for releasing large amounts of NO 2 , particularly when driving at high speed (motorways, ring roads, etc.)
Damage caused- It's a toxic gas which irritates mucous membranes and it's responsible for respiratory pathologies , such as bronchitis, allergies, etc. It also affects the blood ability to transport oxygen.
Nitrogen oxides also contribute to the production of acid rain , which affects the whole ecosystem.
Development- The introduction of catalytic exhaust pipes in the latest years has not reduced consistently the concentration of NO 2 as expected. That's also due to the use of various kinds of fuels: not only petrol, but also diesel and gas for producing energy.
Range of allowed values, according to law (DM n. 60 del 02/02/2002)
NO and NO 2 |
Max concentration per hour ( µ g/mc) |
Max concentration per year ( µ g/mc) |
Max quantity for human health |
200 |
40 |
Tolerance limit |
+ 40 in 2006 decreasing 10 units every year |
+ 8 in 2006 decreasing 2 units every year |
Tolerance limit for ecosystems |
30 |
Danger limit measured on 100sqkm |
400 |
Range of values in urban centres
|
Salute umana (media oraria) (µg/mc) |
Salute umana (media annua) (µg/mc) |
Ecosistema (media annua) (µg/mc) |
Low limit |
100 |
26 |
19.5 |
High limit |
140 |
32 |
24 |
|