The reaction between NO2 at sub-ppm levels and wet or dry sea salt par
ticles was studied using a thermostatted flow reactor. The results ind
icate that the major pathway for nitrogen dioxide reaction, both for d
ry particles and droplets, is 2NO(2) (g, aq)+Cl- (s, aq)-->NO3- (s, aq
)+NOCl (g). The reaction between dry sea salt aerosol and NO2 is rapid
but ceases when less than a monolayer of NaNO3 has been formed. The r
eaction between near-saturated sea salt droplets and NO2 appears to pr
oceed via a liquid-phase process analogous to the reaction between dry
sea salt and NO2. The liquid reaction has a potential to form 0.003 m
u g NO3- m(-3) h(-1) at conditions typical for the polluted marine atm
osphere. If NOCl, produced in the sea salt droplets, survives hydrolys
is it may give a significant contribution to atomic chlorine via photo
lysis.