Manufacturing Emissions

Industrial Processes · Industrial Processes overview

Manufacturing emissions are airborne chemical contaminants released during industrial production, processing, finishing and material handling. In UK factories and workshops, these emissions include solvent vapours, thermal decomposition products, process dusts and reactive chemical mists that expose workers and affect indoor air quality.

Types of manufacturing emissions

Industrial process emissions fall into several categories. Volatile organic compound (VOC) emissions arise from solvent use in coating, printing, cleaning and adhesive application. These are typically the most significant chemical exposure source in manufacturing workplaces. Styrene from GRP composite manufacturing, toluene and xylene from paint and ink, acetone from cleaning, and naphtha from degreasing are all common VOC emissions.

Thermal decomposition emissions occur when plastics, rubber or other polymers are heated above their decomposition temperature. Extrusion, injection moulding, hot-gas welding, cutting and grinding of plastics can release fumes containing aldehydes, aromatic hydrocarbons and hydrogen chloride (from PVC). Bitumen heating for road surfacing and roofing releases polycyclic aromatic hydrocarbons (PAHs) and other bitumen fumes.

Process-specific emissions include isocyanate vapours and aerosols from polyurethane foam and coating manufacture, formaldehyde from resin-bonded wood products and laboratory fixation, and reactive monomer vapours from polymer curing. Each requires specific assessment and control.

Solvent vapour emissions from coating, printing, cleaning and adhesive processes
Thermal decomposition fumes from heated plastics, rubber and composite materials
Bitumen and asphalt fumes from road surfacing and roofing operations
Isocyanate vapours from polyurethane foam, coatings and adhesives
Formaldehyde emissions from resin-bonded materials and laboratory processes

Exposure assessment for manufacturing environments

Assessment begins with a walk-through survey to identify emission sources, tasks with potential exposure, existing controls and observable problems such as odour, visible mist or ineffective LEV. This qualitative stage informs the scope of quantitative monitoring.

Air monitoring strategy depends on the substances present, their WELs and the process variability. For steady-state processes, a single 8-hour TWA sample may be sufficient. For batch, intermittent or variable processes, multiple samples across shifts, tasks and process phases are needed. Start-up, shutdown, maintenance and upset conditions often produce the highest emissions and should not be overlooked.

Direct-reading instruments such as PIDs and FIDs provide immediate concentration data for screening and LEV verification. Sorbent-tube sampling followed by laboratory analysis delivers accurate, substance-specific TWA concentrations for WEL comparison. Multi-substance analysis by GC-MS is efficient where several VOCs are present simultaneously.

Control of manufacturing emissions

The first priority is to reduce emissions at source. Low-VOC or water-based formulations, powder coatings, UV-cured materials and solvent-free adhesives all reduce the quantity of chemical released. Process redesign to minimise open handling, heated open tanks and manual application further reduces emission potential.

Engineering controls are the primary defence where emissions cannot be eliminated. Enclosed process equipment with extraction maintains the lowest operator exposure. Local exhaust ventilation with correctly designed hoods, booths and enclosures captures emissions close to source. General ventilation and air filtration supplement LEV for residual fugitive emissions.

Administrative controls include restricting access to process areas, limiting task duration, scheduling high-emission activities away from other work, and maintaining strict housekeeping to prevent secondary release from spills and residue. Respiratory protective equipment is required as a back-up where engineering controls cannot reduce exposure below the WEL.

Regulatory requirements for industrial emissions

COSHH is the principal UK regulation governing workplace exposure to manufacturing emissions. Employers must assess risk, implement controls, monitor exposure where WELs apply, and maintain records. The Environmental Permitting Regulations and Local Authority Air Pollution Control may also apply where emissions are discharged to atmosphere from the site.

HSE EH40 lists WELs for the substances most commonly found in manufacturing emissions. Where a substance does not have a published WEL, the COSHH competent person must set an in-house exposure standard based on toxicological data and apply the precautionary principle.

Frequently asked questions

Are manufacturing emissions the same as industrial air pollution?

Industrial air pollution typically refers to emissions discharged to the external environment, regulated under environmental permitting. Manufacturing emissions in the occupational hygiene context are the airborne contaminants inside the workplace that workers breathe. Both may require assessment and control, but the regulatory frameworks differ.

Which manufacturing processes produce the highest solvent emissions?

Open-spray painting, open-mould GRP layup, manual parts cleaning in open tanks, screen printing with solvent inks, and hand-lamination with polyester or epoxy resins all generate high local concentrations of solvent vapour. Enclosed or automated alternatives significantly reduce emissions.

Do heated plastic fumes require monitoring?

Yes. Heated plastic fumes can contain decomposition products at concentrations that may exceed WELs for specific substances such as hydrogen chloride, formaldehyde or aromatic hydrocarbons. Monitoring should be conducted whenever plastics are heated, cut or welded without effective fume extraction.

What is the role of background monitoring in factories?

Background monitoring measures ambient concentrations away from specific tasks. It helps identify fugitive emissions, assess general ventilation effectiveness, and determine whether cross-contamination is occurring between process areas. Background data complement personal exposure measurements.

Can manufacturing emissions affect indoor air quality in offices adjacent to production?

Yes. Solvent vapours and other airborne chemicals can migrate through doors, corridors and ventilation systems into adjacent office spaces. This is particularly problematic where production areas are not physically separated or where ventilation systems recirculate air between zones.