Emissions monitoring and limits appropriate measures

These are the emissions limits and appropriate measures for monitoring emissions to air and water for regulated facilities with an environmental permit for treating or transferring healthcare waste.

We may set emission limits and monitoring requirements in your permit, based on your emissions inventory and environmental risk assessment. Where relevant, you should set emission limits at the values provided in this guidance unless you justify and agree alternative values with the Environment Agency.

1. Where you are required to monitor emissions to comply with the requirements of your environmental permit you must follow our monitoring guidance when carrying this out.

2. You must create and maintain an inventory (emissions inventory) of point source emissions to air and water (including emissions to sewer) for your facility.

Emissions to air

1. Your facility’s emissions inventory must include information about the relevant characteristics of point source emissions to air, such as the:

  • average values and variability of flow and temperature
  • average concentration and load values of relevant substances and their variability
  • flammability, lower and higher explosive limits and reactivity
  • presence of other substances that may affect the waste gas treatment system or plant safety – for example, oxygen, nitrogen, water vapour, dust

Chemical emissions to air

2. You may not need to carry out chemical emissions monitoring if both of these conditions apply:

You will need to confirm this through your site specific emissions inventory and environmental risk assessment.

3. If your treatment plant treats pharmaceutically or chemically contaminated wastes, for example, medicinally contaminated sharps (even if fully discharged), you must propose and agree with the Environment Agency emission limits and monitoring requirements for relevant substances. This will be based on an assessment of the range of pharmaceuticals and chemicals in use and their:

  • occurrence and concentration within the waste
  • properties and behaviour when subjected to the treatment process
  • predicted environmental impact

Chemical emission limits and monitoring requirements

4. You should apply the following emission limits and monitoring requirements for point source emissions to air where they are relevant, based on your facility’s emissions inventory and environmental risk assessment. You must comply with any other emission limits or monitoring requirements in your environmental permit.

Here are the emission limits for dust. When using:

  • fabric filters – an emission limit (including unit) of 5 mg/m3
  • other abatement techniques – a higher emission limit of 10 mg/m3 may be appropriate

For dust, the monitoring:

  • frequency is once every 6 months
  • standard or method is BS EN 13284-1

You should report results as the average value of 3 consecutive measurements of at least 30 minutes each.

For total volatile organic compounds (TVOCs) the emission limit is 30 mg/m3, and the monitoring:

  • frequency is once every 6 months
  • standard or method is BS EN 12619

You should report results as the average value of 3 consecutive measurements of at least 30 minutes each.

Microbial emissions to air

5. You must demonstrate that emissions from the plant are controlled during both site commissioning and routine operation.

6. You must monitor and assess microbial emissions using tracer spore suspensions. You can use alternative indicators if you can demonstrate that microbial emissions only come from the waste on site (not from other environmental sources) and are present in enough numbers to provide the same level of test sensitivity.

7. You must comply with the following guidance when monitoring microbial emissions from alternative treatment plant.

Microbial emissions monitoring frequency

8. You must test all devices during commissioning validation and then periodically.

For process bioaerosol emissions monitoring, when you have used a suspension of bacillus spores, you must test as follows:

  • devices which shred or macerate untreated waste – test them during site commissioning and then annually if proven and agreed

  • other devices – test them during site commissioning and then every 4 years

Microbial emissions monitoring methodology

9. You must not use spore strips for bioaerosol emissions monitoring.

10. The quantity of spores must be a minimum of 1 x 106 spores per gram of total waste load.

11. Waste loads processed by the plant during the emissions monitoring tests must be representative of the waste types and waste streams that will be accepted for treatment.

12. You must follow an appropriate assessment methodology, which will depend on whether the waste is shredded or macerated before treatment.

For technologies that shred or macerate the waste prior to treatment

You must prepare and dispense (in a laboratory environment) a dry or liquid suspension of bacillus spores in a number of sealed, small volume plastic containers. Disperse the spores throughout the waste load and process.

For other technologies

You must prepare and dispense (in a laboratory environment) dry or liquid suspensions of bacillus spores, both:

  • loosely on dressings in waste inside containers, such as bags and boxes
  • inside worst case challenge load containers like suction canisters and chest drains

You must disperse the spores throughout the waste load processed.

13. The monitoring must consist of both air monitoring and surface monitoring.

14. You must design your monitoring programme so you take enough samples to quantitatively relate the results to the input dose. The number of samples and location of sampling points will depend on the nature of the process and size of the device.

15. You must take samples:

  • before processing the seeded waste (controls)
  • at intervals during processing the seeded waste – the intervals must relate to the process stages and the timing of potential emissions
  • then periodically for at least 2 hours after the cycle is complete

Through the monitoring programme, you should aim to produce a quantitative ‘estimate’ of the total number of tracer organisms emitted from the device, relative to the input dose by each route.

Monitoring microbial emissions to air

16. You must carry out air monitoring from all of these points, at:

  • identified emission points from the process
  • the site boundaries
  • any other relevant locations within the site – for example, near open vehicle access doors to the building housing the plant

17. You must use active (centrifugal or vacuum) impaction onto agar using Anderson or slit samplers (or equivalent) to sample for bioaerosols. Your data submissions must contain information indicating the recovery efficiency of the method used.

18. You must conduct air monitoring throughout the emissions monitoring exercise. Individual sample times must coincide with the steps in the treatment process where emissions may occur, for example, during the:

  • passage of seeded waste through a shredder
  • unloading of treated material

19. Monitoring must consider all the main sources of emissions that are present at a site, including point source emissions and fugitive emissions.

The main point source emission to air is from venting exhaust gases. You must always treat exhaust gases, for example, by filtering through a high efficiency particulate air (HEPA) filter. Monitoring is needed to demonstrate that treating the gases has been effective. You must monitor at each emission point.

Common sources of fugitive emissions include the following:

a. Macerating untreated clinical waste

This is potentially the most significant source of pathogenic bioaerosols. Your monitoring must demonstrate that the containment measures in place are effective.

b. Macerating treated clinical waste

This treatment reduces the number of microorganisms but does not eliminate them. Your monitoring must demonstrate if additional containment measures are needed.

c. Maintenance or access ports

You must carry out monitoring to make sure that these do not compromise the integrity of the plant and are effectively sealed during operation so emissions are not released. Failed seals and joints may also result in emissions.

d. Bin washing

Cleaning mobile containers may generate pathogenic bioaerosols. Chemical agents used for disinfection may also become aerosolised.

Your monitoring must demonstrate if additional containment measures are needed by contaminating these containers with a liquid ‘spill’ of not less than 100ml and equivalent to 1 x 106 spores per gram of waste typically present in the cart.

Monitoring fugitive microbial emissions to surfaces

20. To support the air monitoring, you must use enough settle plates to form a grid-like pattern around the device or site.

21. The exposure time for each plate, and replacement frequency during testing, should consider contaminants and total microbial load.

22. You must use a regular exposure time and a series of plates at each sampling point. You must also use a grid placement to calculate the total number of organisms that have settled per hour during the monitoring period for:

  • each grid square
  • the whole site

You should compare this to the input dose to provide a quantitative release estimate for the process.

Microbial emission limits

23. You must compare and assess the results of microbial emissions monitoring against the emission limits that follow. This is to demonstrate that the containment and treatment of microbial emissions is effective.

Here are the microbial emission limits for emissions to air and surfaces:

a. Point source emissions to air

For emissions of bacillus spores to air, the limits are 1,000 cfu (colony forming units) per cubic metre.

The limit is based on a seeding dose of 1 x 106 spores per gram of waste load. You should adjust it accordingly if you use a higher or lower seed dose.

The units of the limit (per cubic metre) relate to the overall monitoring period so the limit applies to each individual sample of air, with a calculation made to report the result per cubic metre.

b. Fugitive emissions to air

For fugitive emissions to air, where sample points are more than 10m from the treatment plant, the emissions limit for bacillus spores is 300 cfu per cubic metre.

c. Fugitive emissions to surfaces

For fugitive emissions of bacillus spores to surfaces, where sample points are less than 10m from the treatment plant, the emissions limit for bacillus spores is 20,000 cfu per square metre per hour.

For fugitive emissions to surfaces, where sample points are more than 10m from the treatment plant, the emissions limit for bacillus spores is 5,000 cfu per square metre per hour.

In both cases, the limit is based on a seeding dose of 1 x 106 spores per gram of waste load. You should adjust it accordingly if you use a higher or lower seeding dose.

The units relate to the overall monitoring period so the cfu limit applies to each individual:

  • sample of air – a calculation is made to report the result per cubic metre
  • settle plate (this is not an average) – a calculation is made to adjust for surface area of a settle plate and exposure time (for example, if you use settle plates for only 15 minutes of every hour then you must multiply the result by 4)

Emissions to water or sewer

1. Your facility’s emissions inventory must include information about the relevant characteristics of point source emissions to water or sewer, such as:

  • average values and variability of flow, pH, temperature and conductivity
  • average concentration and load values of relevant substances and their variability – for example, COD (chemical oxygen demand) and TOC (total organic carbon), nitrogen species, phosphorus, metals, priority substances or micropollutants
  • data on bio-eliminability – for example, BOD (biochemical oxygen demand), BOD to COD ratio, Zahn-Wellens test, biological inhibition potential, for example, inhibition of activated sludge

2. For relevant emissions to water or sewer identified by the emissions inventory, you must carry out monitoring of key process parameters (for example, waste water flow, pH, temperature, conductivity, or BOD) at key locations. For example, these could either be at the:

  • inlet or outlet (or both) of the pre-treatment
  • inlet to the final treatment
  • point where the emission leaves the facility boundary

Chemical emissions to water or sewer

3. You may not need to carry out chemical or pharmaceutical emissions monitoring if both of these apply:

You will need to confirm this through your site specific emissions inventory.

4. If your treatment plant is authorised to process medicinally or chemically contaminated waste, for example, medicinally contaminated sharps (even if fully discharged), you must propose and agree with the Environment Agency emission limits and monitoring requirements for relevant substances. You will need to assess the range of chemicals and pharmaceuticals in use and their:

  • occurrence and concentration within the waste
  • properties and behaviour when subjected to the treatment process
  • predicted environmental impact

Microbial emissions to water or sewer

5. Where the treatment process produces a wastewater you must also monitor this at intervals during the microbial emissions tests. You must follow the method and frequency of the test set out in the section on microbial emissions to air.

6. You must representatively sample wastewater for microbial emissions before it enters the drainage system and as near to the point of origin (the treatment plant) as possible.

7. You must compare and assess the results of microbial emissions monitoring against the following emission limit to demonstrate that the treatment of microbial emissions is effective.

Emission limits for microbial emissions to water

The emission limit for bacillus spores to water or sewer is 300 cfu per litre.

This limit is based on a seeding dose of 1 x 106 spores per gram of waste load. You should adjust it accordingly if you use a higher or lower seed dose.

These units relate to the overall monitoring period so the cfu limit applies to each individual sample of water taken, with a calculation made to report the result per litre.