In case anyone is looking to get this mod working in 1.1, you'll need to make the following changes:
In pollution_detector_0.6.0/info.json, line 7, change
"factorio_version": "0.18",
TO
"factorio_version": "1.1",
And in pollution_detector_0.6.0/control.lua, lines 51–53, change
local params = {parameters={
{index = 1, signal = {type = "virtual", name = "pd-pollution"}, count = pollution_count}
}}
TO
local params = {
{index = 1, signal = {type = "virtual", name = "pd-pollution"}, count = pollution_count}
}