A corona discharge apparatus comprising: (a) an elongate inner electrode, (b) an elongate dielectric sleeve mounted on the inner electrode, (c) an elongate outer electrode mounted on the dielectric sleeve, and (d) an ozone-producing region over which the outer electrode extends, the ozone-producing region having an inlet end and an outlet end, the ozone-producing region defined by three sealing members at the inlet end thereof and three sealing members at the outlet end thereof, the sealing members forming a seal between the inner electrode and the dielectric sleeve.
