At the onset of the Covid-19 pandemic, it was initially believed that the main vectors of virus transmission were via droplets and fomites. However, airborne transmission was subsequently confirmed with studies concluding that the “transmission of SARS-CoV-2 occurred preferentially indoors, suggesting a need for a revolution in building design and operation, in order to make clean air supply into buildings as important as clean water and food.”¹

In Ireland the Safety Health and Welfare at Work Act (2005) is the primary legislation governing workplace health and safety. Under section 8 of the Act, every employer is required to ensure, in so far as is reasonably practicable, the safety, health and welfare at work of their employees.^2-

The Health and Safety Authority (HSA) has overall responsibility for the administration and enforcement of health and safety at work and it monitors compliance with legislation in the workplace. The HSA can take enforcement measures up to and including prosecution. 

The Safety, Health and Welfare at Work (Biological Agents) Regulations (2013), and associated Code of Practice,³ sets down the requirement for the protection of workers from health risks associated with biological agents in the workplace. It also provides further safety measures under the Safety, Health and Welfare at Work (General Application) Regulations (2007) where employers are required to make sure sufficient fresh air is provided in enclosed places of work. 

In addition, in May 2023 the HSA published and introduced a Code of Practice on Indoor Air Quality, in accordance with Section 60 of the Safety, Health and Welfare at Work Act 2005.⁴ This Code of Practice is relevant to all places of work and states that employers should use this code to develop policies, conduct risk assessments and implement control measures to address indoor air quality and ventilation in the workplace.

The health effects from poor indoor air quality can include the following:

• Headache 

• Dizziness

• Nausea

• Fatigue

• Difficulty concentrating

• Sinus problems 

• Congestion 

•
Irritation of the mucus membranes of the eyes, nose and/or throat, causing coughing and/or sneezing 

•
Respiratory illnesses such as Covid-19 or legionnaires’ disease 

•
Cancer from long-term exposure to radon, asbestos etc.

Under Section (19) of the Safety, Health and Welfare at Work Act (2005), employers are required to conduct a Biological Agents and Indoor Air Quality risk assessment to determine the air quality in the workplace and the risk assessments should be located as per Section (20) of the (2005) Act, in the workplace Safety Statement.

The Code states that it is important to ensure that air quality inspections are carried out by a competent person depending on the specific circumstances and type of workplace. 

According to the (2005) Act, an individual is deemed to be a competent person if they possess sufficient training, experience and knowledge appropriate to the nature of the work to be undertaken. 

When conducting air quality risk assessments, the Code sets out the importance of assessing occupancy levels, activity and space. It also specifies that a minimum floor space of 4.65 square metres should be allowed for every person employed in any room and at least 11.3 cubic metres should be provided for each person at work in a room (other than an office) at any one time. 

Elevated levels of carbon dioxide in the air can be an indicator of poor air quality and carbon dioxide monitors can be used to assess these levels as part of the risk assessment process but should not be considered the sole indicator in establishing air quality.

Carbon dioxide concentrations above 1,400ppm, are likely to be indicative of poor ventilation and the HSA Code of Practice for Indoor Air Quality recommends maintaining concentrations below 1,000 ppm for adequate ventilation.

Where there are high carbon dioxide concentration levels or the levels are increasing upwards towards the indicative values of poor ventilation, it is recommended that mitigation measures are taken to either increase ventilation or adjust occupancy.

Improving indoor air quality can be supported using high efficiency particulate air (HEPA) filtration units, which will require risk assessment by a competent person.⁵

To conclude, the opening of windows, while a pragmatic approach, does not determine that ventilation is sufficient in the workplace. Workers spend a significant amount of time indoors and the quality of air within indoor work environments has a direct effect on their health, wellbeing and productivity.

Recognition of the importance of ventilation in the workplace has been demonstrated in Belgium where it is now mandated that carbon dioxide measurements are conducted in all closed spaces accessible to the public.

1. Morawska L, Li Y, Salthammer T. Lessons from the Covid-19 pandemic for ventilation and indoor air quality. Science 2024, Jul 25; 38(670):396-401. doi: 10.1126/science.adp2241
2. Safety, Health and Welfare at Work Act (2005) https://www.irishstatutebook.ie/eli/2005/act/10/enacted/en/print
3. 2020 Biological Agents Code of Practice for the Safety, Health and Welfare at Work (Biological Agents) Regulations, 2013 and 2020 (SI No. 572 of 2013 as amended by S.I. No. 539 of 2020) COP biological agents 2023 rebranded.indd
4. The HSA Code of Practice on Indoor Air Quality. https://www.hsa.ie/eng/publications_and_forms/publications/codes_of_practice/code_of_practice_for_indoor_air_quality.pdf
5. Conway Morris A, Sharrocks K, Bousfield R et al. The Removal of Airborne Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Other Microbial Bioaerosols by Air Filtration on Coronavirus Disease 2019 (Covid-19) Surge Units. Clinical Infectious Diseases 2022, Jul 1; 75(1):e97-e101. doi: 10.1093/cid/ciab933