Division BAT 4 BAT is to monitor emissions to air with at least the frequency given below and in accordance with EN standards. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality.

United Kingdom

Substance/Parameter	Fuel/Process/Type of combustion plant	Combustion plant total rated thermal input	Standard(s)^f1	Minimum monitoring frequency^f2	Monitoring associated with
Generic EN standards for continuous measurements are EN 15267-1, EN 15267-2, EN 15267-3, and EN 14181. EN standards for periodic measurements are given in the table.
The monitoring frequency does not apply where plant operation would be for the sole purpose of performing an emission measurement.
In the case of plants with a rated thermal input of < 100 MW operated < 1 500 h/yr, the minimum monitoring frequency may be at least once every six months. For gas turbines, periodic monitoring is carried out with a combustion plant load of > 70 %. For co-incineration of waste with coal, lignite, solid biomass and/or peat, the monitoring frequency needs to also take into account Part 6 of Annex VI to the IED.
In the case of use of SCR, the minimum monitoring frequency may be at least once every year, if the emission levels are proven to be sufficiently stable.
In the case of natural-gas-fired turbines with a rated thermal input of < 100 MW operated < 1 500 h/yr, or in the case of existing OCGTs, PEMS may be used instead.
PEMS may be used instead.
Two sets of measurements are carried out, one with the plant operated at loads of > 70 % and the other one at loads of < 70 %.
As an alternative to the continuous measurement in the case of plants combusting oil with a known sulphur content and where there is no flue-gas desulphurisation system, periodic measurements at least once every three months and/or other procedures ensuring the provision of data of an equivalent scientific quality may be used to determine the SO₂ emissions.
In the case of process fuels from the chemical industry, the monitoring frequency may be adjusted for plants of < 100 MW_th after an initial characterisation of the fuel (see BAT 5) based on an assessment of the relevance of pollutant releases (e.g. concentration in fuel, flue-gas treatment employed) in the emissions to air, but in any case at least each time that a change of the fuel characteristics may have an impact on the emissions.
If the emission levels are proven to be sufficiently stable, periodic measurements may be carried out each time that a change of the fuel and/or waste characteristics may have an impact on the emissions, but in any case at least once every year. For co-incineration of waste with coal, lignite, solid biomass and/or peat, the monitoring frequency needs to also take into account Part 6 of Annex VI to the IED.
In the case of process fuels from the chemical industry, the monitoring frequency may be adjusted after an initial characterisation of the fuel (see BAT 5) based on an assessment of the relevance of pollutant releases (e.g. concentration in fuel, flue-gas treatment employed) in the emissions to air, but in any case at least each time that a change of the fuel characteristics may have an impact on the emissions.
In the case of plants with a rated thermal input of < 100 MW operated < 500 h/yr, the minimum monitoring frequency may be at least once every year. In the case of plants with a rated thermal input of < 100 MW operated between 500 h/yr and 1 500 h/yr, the monitoring frequency may be reduced to at least once every six months.
If the emission levels are proven to be sufficiently stable, periodic measurements may be carried out each time that a change of the fuel and/or waste characteristics may have an impact on the emissions, but in any case at least once every six months.
In the case of plants combusting iron and steel process gases, the minimum monitoring frequency may be at least once every six months if the emission levels are proven to be sufficiently stable.
The list of pollutants monitored and the monitoring frequency may be adjusted after an initial characterisation of the fuel (see BAT 5) based on an assessment of the relevance of pollutant releases (e.g. concentration in fuel, flue-gas treatment employed) in the emissions to air, but in any case at least each time that a change of the fuel characteristics may have an impact on the emissions.
In the case of plants operated < 1 500 h/yr, the minimum monitoring frequency may be at least once every six months.
In the case of plants operated < 1 500 h/yr, the minimum monitoring frequency may be at least once every year.
Continuous sampling combined with frequent analysis of time-integrated samples, e.g. by a standardised sorbent trap monitoring method, may be used as an alternative to continuous measurements.
If the emission levels are proven to be sufficiently stable due to the low mercury content in the fuel, periodic measurements may be carried out only each time that a change of the fuel characteristics may have an impact on the emissions.
The minimum monitoring frequency does not apply in the case of plants operated < 1 500 h/yr.
Measurements are carried out with the plant operated at loads of > 70 %.
In the case of process fuels from the chemical industry, monitoring is only applicable when the fuels contain chlorinated substances.
NH₃	When SCR and/or SNCR is used	All sizes	Generic EN standards	Continuous^f3 ^f4	BAT 7
NO_X	Coal and/or lignite including waste co-incineration Solid biomass and/or peat including waste co-incineration HFO- and/or gas-oil-fired boilers and engines Gas-oil-fired gas turbines Natural-gas-fired boilers, engines, and turbines Iron and steel process gases Process fuels from the chemical industry IGCC plants	All sizes	Generic EN standards	Continuous ^f5	BAT 20 BAT 24 BAT 28 BAT 32 BAT 37 BAT 41 BAT 42 BAT 43 BAT 47 BAT 48 BAT 56 BAT 64 BAT 65 BAT 73
NO_X	Combustion plants on offshore platforms	All sizes	EN 14792	Once every year^f6	BAT 53
N₂O	Coal and/or lignite in circulating fluidised bed boilers Solid biomass and/or peat in circulating fluidised bed boilers	All sizes	EN 21258	Once every year^f7	BAT 20 BAT 24
CO	Coal and/or lignite including waste co-incineration Solid biomass and/or peat including waste co-incineration HFO- and/or gas-oil-fired boilers and engines Gas-oil-fired gas turbines Natural-gas-fired boilers, engines, and turbines Iron and steel process gases Process fuels from the chemical industry IGCC plants	All sizes	Generic EN standards	Continuous	BAT 20 BAT 24 BAT 28 BAT 33 BAT 38 BAT 44 BAT 49 BAT 56 BAT 64 BAT 65 BAT 73
CO	Combustion plants on offshore platforms	All sizes	EN 15058	Once every year	BAT 54
SO₂	Coal and/or lignite including waste co-incineration Solid biomass and/or peat including waste co-incineration HFO- and/or gas-oil-fired boilers HFO- and/or gas-oil-fired engines Gas-oil-fired gas turbines Iron and steel process gases Process fuels from the chemical industry in boilers IGCC plants	All sizes	Generic EN standards and EN 14791	Continuous ^f8 ^f9	BAT 21 BAT 25 BAT 29 BAT 34 BAT 39 BAT 50 BAT 57 BAT 66 BAT 67 BAT 74
SO₃	When SCR is used	All sizes	No EN standard available	Once every year	—
Gaseous chlorides, expressed as HCl	Coal and/or lignite Process fuels from the chemical industry in boilers	All sizes	EN 1911	Once every three months ^f10 ^f11	BAT 21 BAT 57
	Solid biomass and/or peat	All sizes	Generic EN standards	Continuous^f12 ^f13	BAT 25
	Waste co-incineration	All sizes	Generic EN standards	Continuous	BAT 66 BAT 67
HF	Coal and/or lignite Process fuels from the chemical industry in boilers	All sizes	No EN standard available	Once every three months	BAT 21 BAT 57
	Solid biomass and/or peat	All sizes	No EN standard available	Once every year	BAT 25
	Waste co-incineration	All sizes	Generic EN standards	Continuous	BAT 66 BAT 67
Dust	Coal and/or lignite Solid biomass and/or peat HFO- and/or gas-oil-fired boilers Iron and steel process gases Process fuels from the chemical industry in boilers IGCC plants HFO- and/or gas-oil-fired engines Gas-oil-fired gas turbines	All sizes	Generic EN standards and EN 13284-1 and EN 13284-2	Continuous ^f14	BAT 22 BAT 26 BAT 30 BAT 35 BAT 39 BAT 51 BAT 58 BAT 75
Dust	Waste co-incineration	All sizes	Generic EN standards and EN 13284-2	Continuous	BAT 68 BAT 69
Metals and metalloids except mercury (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Tl, V, Zn)	Coal and/or lignite Solid biomass and/or peat HFO- and/or gas-oil-fired boilers and engines	All sizes	EN 14385	Once every year^f15	BAT 22 BAT 26 BAT 30
	Waste co-incineration	< 300 MW_th	EN 14385	Once every six months	BAT 68 BAT 69
	Waste co-incineration	≥ 300 MW_th	EN 14385	Once every three months^f16	BAT 68 BAT 69
	IGCC plants	≥ 100 MW_th	EN 14385	Once every year	BAT 75
Hg	Coal and/or lignite including waste co-incineration	< 300 MW_th	EN 13211	Once every three months ^f17	BAT 23
	Coal and/or lignite including waste co-incineration	≥ 300 MW_th	Generic EN standards and EN 14884	Continuous ^f18	BAT 23
	Solid biomass and/or peat	All sizes	EN 13211	Once every year^f19	BAT 27
	Waste co-incineration with solid biomass and/or peat	All sizes	EN 13211	Once every three months	BAT 70
	IGCC plants	≥ 100 MW_th	EN 13211	Once every year^f20	BAT 75
TVOC	HFO- and/or gas-oil-fired engines Process fuels from the chemical industry in boilers	All sizes	EN 12619	Once every six months	BAT 33 BAT 59
TVOC	Waste co-incineration with coal, lignite, solid biomass and/or peat	All sizes	Generic EN standards	Continuous	BAT 71
Formaldehyde	Natural-gas in spark-ignited lean-burn gas and dual fuel engines	All sizes	No EN standard available	Once every year	BAT 45
CH₄	Natural-gas-fired engines	All sizes	EN ISO 25139	Once every year^f21	BAT 45
PCDD/F	Process fuels from the chemical industry in boilers Waste co-incineration	All sizes	EN 1948-1, EN 1948-2, EN 1948-3	Once every six months ^f22	BAT 59 BAT 71

Annotations

Footnotes

f1: Generic EN standards for continuous measurements are EN 15267-1, EN 15267-2, EN 15267-3, and EN 14181. EN standards for periodic measurements are given in the table.
f2: The monitoring frequency does not apply where plant operation would be for the sole purpose of performing an emission measurement.
f3: In the case of plants with a rated thermal input of < 100 MW operated < 1 500 h/yr, the minimum monitoring frequency may be at least once every six months. For gas turbines, periodic monitoring is carried out with a combustion plant load of > 70 %. For co-incineration of waste with coal, lignite, solid biomass and/or peat, the monitoring frequency needs to also take into account Part 6 of Annex VI to the IED.
f4: In the case of use of SCR, the minimum monitoring frequency may be at least once every year, if the emission levels are proven to be sufficiently stable.
f5: In the case of natural-gas-fired turbines with a rated thermal input of < 100 MW operated < 1 500 h/yr, or in the case of existing OCGTs, PEMS may be used instead.
f6: PEMS may be used instead.
f7: Two sets of measurements are carried out, one with the plant operated at loads of > 70 % and the other one at loads of < 70 %.
f8: As an alternative to the continuous measurement in the case of plants combusting oil with a known sulphur content and where there is no flue-gas desulphurisation system, periodic measurements at least once every three months and/or other procedures ensuring the provision of data of an equivalent scientific quality may be used to determine the SO₂ emissions.
f9: In the case of process fuels from the chemical industry, the monitoring frequency may be adjusted for plants of < 100 MW_th after an initial characterisation of the fuel (see BAT 5) based on an assessment of the relevance of pollutant releases (e.g. concentration in fuel, flue-gas treatment employed) in the emissions to air, but in any case at least each time that a change of the fuel characteristics may have an impact on the emissions.
f10: If the emission levels are proven to be sufficiently stable, periodic measurements may be carried out each time that a change of the fuel and/or waste characteristics may have an impact on the emissions, but in any case at least once every year. For co-incineration of waste with coal, lignite, solid biomass and/or peat, the monitoring frequency needs to also take into account Part 6 of Annex VI to the IED.
f11: In the case of process fuels from the chemical industry, the monitoring frequency may be adjusted after an initial characterisation of the fuel (see BAT 5) based on an assessment of the relevance of pollutant releases (e.g. concentration in fuel, flue-gas treatment employed) in the emissions to air, but in any case at least each time that a change of the fuel characteristics may have an impact on the emissions.
f12: In the case of plants with a rated thermal input of < 100 MW operated < 500 h/yr, the minimum monitoring frequency may be at least once every year. In the case of plants with a rated thermal input of < 100 MW operated between 500 h/yr and 1 500 h/yr, the monitoring frequency may be reduced to at least once every six months.
f13: If the emission levels are proven to be sufficiently stable, periodic measurements may be carried out each time that a change of the fuel and/or waste characteristics may have an impact on the emissions, but in any case at least once every six months.
f14: In the case of plants combusting iron and steel process gases, the minimum monitoring frequency may be at least once every six months if the emission levels are proven to be sufficiently stable.
f15: The list of pollutants monitored and the monitoring frequency may be adjusted after an initial characterisation of the fuel (see BAT 5) based on an assessment of the relevance of pollutant releases (e.g. concentration in fuel, flue-gas treatment employed) in the emissions to air, but in any case at least each time that a change of the fuel characteristics may have an impact on the emissions.
f16: In the case of plants operated < 1 500 h/yr, the minimum monitoring frequency may be at least once every six months.
f17: In the case of plants operated < 1 500 h/yr, the minimum monitoring frequency may be at least once every year.
f18: Continuous sampling combined with frequent analysis of time-integrated samples, e.g. by a standardised sorbent trap monitoring method, may be used as an alternative to continuous measurements.
f19: If the emission levels are proven to be sufficiently stable due to the low mercury content in the fuel, periodic measurements may be carried out only each time that a change of the fuel characteristics may have an impact on the emissions.
f20: The minimum monitoring frequency does not apply in the case of plants operated < 1 500 h/yr.
f21: Measurements are carried out with the plant operated at loads of > 70 %.
f22: In the case of process fuels from the chemical industry, monitoring is only applicable when the fuels contain chlorinated substances.