Debian shutdown at "ACPI: Critical trip point"

Right a few minutes ago my Debian executed a fine shutdown; in /var/log/syslog.log there is:

Apr  3 16:46:38 cdiemst kernel: [ 4336.685904] ACPI: Critical trip point
Apr  3 16:46:38 cdiemst kernel: [ 4336.685920] Critical temperature reached (85 C), shutting down.
Apr  3 16:46:38 cdiemst shutdown[7341]: shutting down for system halt
Apr  3 16:46:38 cdiemst init: Switching to runlevel: 0
Apr  3 16:46:40 cdiemst kernel: [ 4338.723411] Critical temperature reached (77 C), shutting down.
Apr  3 16:54:42 cdiemst kernel: imklog 3.18.6, log source = /proc/kmsg started.

After some research it became obvious, that:
1. Either the fan needs to be cleaned
2. Or there should be set a throttling option for the processors (as described by alioth at: http://alioth.debian.org/~fjp/log/posts/Preventing_overheating_of_my_hp2510p.html).

Checking at:

cdiemst:/proc/acpi/thermal_zone/TZS0# cat trip_points
critical (S5):           85 C
cdiemst:/proc/acpi/thermal_zone/TZS1# cat trip_points
critical (S5):           111 C

shows there is no processor-throttling option enabled with passive trip points. So I have tried with a workaround, changing /etc/sysfs.conf to contain:

class/thermal/thermal_zone0/passive = 80000
class/thermal/thermal_zone1/passive = 80000

as proposed by alioth in the abovementioned article. Waiting for the next temperature anomaly.