An assessment of the risk to health from work activities within the British Library
Conducted on behalf of: Mr K. Miller - The British Library, London.
By: Abbas Shakeri - Envirocheck (UK) Limited.
Assessment Date: October 2001
Contents
1.0 Introduction
Under The Control of Substances Hazardous to Health Regulations (COSHH) 1999, Substances Hazardous to Health are defined as any substance that creates a hazard to the health of any person arising out of or in connection with work under the control of an employer.
They may include:
- Any substance listed in the CHIP 2 Regulations1994 and for which the classification is specified as either toxic, very toxic, harmful, corrosive or irritant
- Any substance that has an MEL or OES
- A Micro-organism that creates any kind of hazard
- Dust of any kind when present in substantial concentrations in air.
Under Regulation 6 of COSHH an employer is required to make a suitable and sufficient assessment of the risks to health in the workplace. Where substances are known to be used that fall into one or more of above categories an assessment of the occupational exposure is important and will be able to be incorporated into the appropriate Risk Assessment.
The exposure assessment will enable the employer to make a valid decision about whether work activities are likely to result in any employee or non employee being 'exposed to significant levels of hazardous substances' and to identify the measures needed to prevent or adequately control exposure.
Significant exposure is considered to be present where an employee is or is liable to be exposed to a concentration of the substance in air exceeding half the Occupational Exposure Limit (OEL) as defined in EH 40 by the Health and Safety Executive.
2.0 Assessment objectives
- To identify and measure the exposure of employees to critical hazardous substances highlighted
- To compare the measured levels with Occupational Exposure Limits published in EH 40/2001 Published by the HSE
- Make appropriate recommendations.
Concern has been raised regarding the adverse effects of various Volatile Organic Compounds and Aldehydes with M.E, therefore Envirocheck (UK) Limited were commissioned to carry out an appropriate assessment of the indoor environment such that an informed opinion could be made regarding the "risks" to employees working within the area concerned.
The site visit took place on the 4 October 2001 during which time the indoor environment was assessed both visually and by direct measurement.
3.0 Discussions and methods of assessment
Bacterial
Analysis is carried out with respect to microbiological growth within both ductwork and associated services. Levels of contamination are determined by the total colony forming units per cubic meter using a MAS-100 Centrifugal Sampler.
Bacteria in air and fungi in air are measured in units expressed as Colony Forming Units per m3 (cfu/m3). The surface of nutrient agars (formulated to favour the growth of either bacteria or yeast & mould) are exposed to measure volumes of air drawn through a centrifugal sampler. Samples are then incubated and analysed by an independent NAMAS - registered laboratory. A wide range of population and species is detectable.
Maximum limits:
Bacteria: 500 cfu/m3
Fungi: 300 cfu/m3
Comfort factor
Analysis is carried out to determine whether effects of temperature and humidity are contributing to poor working environments. Within their own parameters apart from instigating discomfort if too hot or too humid, they pose minimal problems to the indoor environment. However their contribution to other factors such as increased bacterial and fungal growth may instigate a much greater cause for concern.
Humidity -
Humidity can have adverse affect on the growth of mould and dust mites within an area if allowed to become too high. Rapid growth occurs when levels of humidity increase above 70%, with great effects to respiratable illnesses such as asthma. In the same aspect if levels of humidity become too dry, below 40% this too can have adverse effects, with some people susceptible to sore throats due to the dryness of the air.
The optimum level of humidity should be 40 - 70%, with much dependant on the indoor environment in question, and the seasonal variation as to the best level for the area in question.
Temperature -
Temperature levels within an indoor environment will vary greatly depending on the time of year and personal preference. However increased temperature within a confined space such as an indoor environment can instigate a more suitable environment for the growth of unwanted bacteria and fungi.
Analysis must be carried out in close collaboration with other parameters analysed to determine characteristics of change.
In general it would be reasonable to maintain a temperature within 19°C - 23°C within a building.
Ozone
A glass fibre filter impregnated with nitrite was used for this test. Air was drawn onto the filter using a pump any ozone present in the air oxidises nitrite to nitrate, which determined by ion chromatography (Method ID-2147, Occupational Health and Administration).
The current OES for ozone is 0.2 ppm in air averaged over 15-minute reference period.
Gases
Analysis is carried out in respect of the amount of that gas present within that area of air. Levels of contamination can have varied effects on those inhabitants in the area of concern, depending on the gas in question. See following for further details.
Carbon dioxide (CO2) -
Carbon dioxide is present in the natural environment, being produced by combustion of biological processes. Carbon dioxide is present at typical levels of about 300 ppm in the ambient urban environment though this can rise substantially inside occupied buildings. The Health & Safety Executive has set an Occupational Exposure Standard (OES) of 15,000 ppm as a 15-minute time-weighted average. OESs are set at a level at which there is no indication of any risk to health and employers are simply expected to ensure that OES limits are not exceeded.
However, carbon dioxide levels are often used as a guide to whether or not a space has a sufficient quantity of fresh air. The International Energy Agency advice is as follows:-
- levels of carbon dioxide below 1000 ppm indicate good ventilation
- levels between 1000-2000 ppm indicate low rates of ventilation
- levels above 2000 ppm suggest poor rates of ventilation, which can produce a stuffy feeling, encourage odours to linger and give rise to complaints of stale air.
Carbon monoxide (CO) -
Carbon monoxide results from the incomplete combustion of fossil fuels. CO combines with the haemoglobin in the blood thus reducing the oxygen-carrying capacity of the blood. Natural ambient background levels generally range between 0.01 and 0.2 ppm, but concentrations in urban areas are higher and vary greatly with the weather and traffic density.
The OES for Carbon monoxide is 200 ppm (15-minute reference period) . The World Health Organisation (WHO) recommended guideline for CO is 90ppm averaged over a 15-minute period. WHO Guidelines are designed to protect the most vulnerable groups of the population and are therefore not considered to be particularly relevant to assess the potential health effects of pollutants on the general; population as opposed to workers.
Volatile Organic Compounds
The exposure measurements were carried out as follows and in accordance with MDHS 72 -Volatile Organic Compounds in Air.
Background sampling for Solvents using Activated Charcoal Sorbent Tubes connected to a low flow sampling pump running at 200ml/min situated at a representative location.
Total particulates/fibres
The Health & Safety Executive in its Guidance Note EH 40/01 stipulates an Occupational Exposure Limit (OEL) for total inhalable dust of 10 mg/m3. This is based on an 8-hour weighted-average reference period. The OEL is the concentration of an airborne substance averaged over a reference period that should not be exceeded, the employer must promptly identify the reasons and take appropriate steps to reduce exposures as soon as it is reasonably possible.
Direct measurement of the particulate matter released by the process was achieved with a TSI DustTrak. The DustTrak is a laser particle counter that is able to express real time particle counts of different fractions of particulate matter as mg/m3. Air is drawn at a constant flow rate through a chamber containing a laser and the scattering of light by the particles is used to calculate and display the particle concentration.
The DustTrak was placed in each selected location with the sampling nozzle facing the employees work station in line with their nasal passage.
4.0 Assessment results
Bacterial
| Sample Number | Sample Lab Ref | Sample Location | Aerobic Bacteria (cfu) | Fungi (cfu) |
|---|---|---|---|---|
| 1 | 3463 | 1st floor office | 95 | 10 |
| 2 | 3464 | 1st floor office | 80 | 5 |
Comfort factor
| Target | Sample location | Reading | Acceptable Range (°C) | Comments |
|---|---|---|---|---|
| Temperature | 1st floor office | 21.9 | 19 - 23 | Satisfactory |
| Humidity | 1st floor office | 50.6 | 40 - 70 | Satisfactory |
Gases
| Target | Sample location | Reading | Acceptable Range | Comments |
|---|---|---|---|---|
| Carbon dioxide | 1st floor office | 634 ppm | <1000 | Satisfactory |
| Carbon monoxide | 1st floor office | 0 ppm | 90 | Satisfactory |
Ozone
| Target | Sample location | Reading | EH/40 Limit | Comments |
|---|---|---|---|---|
| Ozone | 1st floor office | <0.005 | 0.2 ppm | Below detection level |
Total particulates/fibres
| Target | Readings | EH/40 Limit | Comments |
|---|---|---|---|
| Total Particulate matter | 0.002 mg/m3 | 10.0 mg/m3 | Satisfactory |
| Identified Fibre | General Dust | 10.0 mg/m3 | Satisfactory |
Aldehydes
| Target | Readings | EH/40 Limit | Comments |
|---|---|---|---|
| Formaldehyde | <0.001 ppm | 2 | Below detection level |
Volatile Organic Compounds
| Target | Readings (µg) | EH/40 Limit (mg/m3) | Comments |
|---|---|---|---|
| Chloromethane | <0.05 ppm | 105 | Below detection level |
| Bromomethane | <0.005 ppm | 20 | Below detection level |
| Vinyl chloride | <0.005 ppm | 7 | Below detection level |
| Chloroethane | <5 | 2700 | Below detection level |
| Dichloromethane | <1 | 350 | Below detection level |
| Acetone | <2 | 1810 | Below detection level |
| Carbon disulphide | <0.001 | 32 | Below detection level |
| 1,1-Dicloroethane | <0.1 | 823 | Below detection level |
| Trans-1,2-Dichloroethane | <0.01 | 823 | Below detection level |
| Chloroform | <0.001 | 9.9 | Below detection level |
| 1,2-Dichloroethane | 0.00 ppm | 21 | Below detection level |
| Butanone (MEK) | <0.1 | 10.85 | Below detection level |
| 1,1,1-Trichloroethane | <5 | 1110 | Below detection level |
| Carbon Tetrachloride | <0.001 | 13 | Below detection level |
| Bromodichloroethane | <0.1 | - | Below detection level |
| 4-Methyl-2-Pentanone (MIBK) | <2 | 208 | Below detection level |
| 1 2-Dichloropropane | <0.1 | - | Below detection level |
| Dibromochloromethane | <1 | 872 | Below detection level |
| 1,1,2-Trichloroethane | <2 | 1110 | Below detection level |
| Benzene | 0.00 ppm | 16 | Below detection level |
| Trans-1,3-Dichloropropane | <0.1 | - | Below detection level |
| Bromoform | 0.00 | 5.3 | Below detection level |
| 2-Hexanone (MBK) | <0.01 | 21 | Below detection level |
| Tetrachloroethane | <0.1 | 2700 | Below detection level |
| 1,1,2,2-Tetrachloroethane | <0.1 | - | Below detection level |
| Toluene | <1 | 191 | Below detection level |
| Chlorobenzene | <1 | 234 | Below detection level |
| Ethylbenzene | <1 | 441 | Below detection level |
| Styrene | <1 | 430 | Below detection level |
| Xylenes | <1 | 441 | Below detection level |
| o-Xylenes | <1 | 441 | Below detection level |
| Freon 113 | <0.1 | 441 | Below detection level |
| Methyl t-butyl ether | <0.01 | 92 | Below detection level |
| Cis-1,2-Dichloroethene | 0.00 | 92 | Below detection level |
| 1,3-Dichloropropaene | <0.1 | - | Below detection level |
| Trichloroethane | <1 | 1110 | Below detection level |
5.0 Summary
From the tests carried out it is concluded that all readings proved to be satisfactory at the time of our survey.
All VOCs tested were below the detection level, as expected from such an environment. It is important to note that the building benefits from a "well maintained" ventilation system, providing adequate air movement within the indoor environment. The ventilation plant is designed such that it provides a specific amount of fresh air supply into the building, CO2 levels are always a good indication of the amount of fresh air supplied into a building.
Due to the fact that the ventilation system is well balanced and maintained ,if there ever was a cause for concern with regards to VOCs & Aldehydes the rate at which the air is changed within the building would diffuse the potential risk.
The results show that at the time of testing all parameters were well within the required limits, and that the indoor air quality can therefore be described as very good.
6.0 Conclusions
The indoor air quality was seen to be very good at the time of survey.
In order to maintain or monitor air quality you may consider the Introduction of a regular indoor air quality monitoring system, which may include the following: -
- Bacterial samples from the indoor air and ventilation plant
- Comfort factor analysis (temperature and humidity)
- Gas sampling analysis (carbon dioxide)
- Particulate (dust) monitoring
- Ventilation system inspection
- Ozone (in areas with large number of printing and copying facility).
The above checks should be carried out at least twice per annum (ideally quarterly) and all information should be kept within the site Log Book.
