Increasing evidence indicates that humidity can play a role in the survival of membrane-bound viruses, such as SARS-CoV-2 (63–65). Previous research has found that, at typical indoor temperatures, relative humidity (RH) above 40% is detrimental to the survival of many viruses, including CoVs in general (63, 66, 67), and higher indoor RH has been shown to reduce infectious influenza virus in simulated coughs (67). Based upon studies of other viruses, including CoVs, higher RH also decreases airborne dispersal by maintaining larger droplets that contain viral particles, thus causing them to deposit onto room surfaces more quickly (63, 68, 69). Higher humidity likely negatively impacts lipid-enveloped viruses, like CoVs, through interactions with the polar membrane heads that lead to conformational changes of the membrane, causing disruption and inactivation of the virus (70, 71). Furthermore, changes in humidity can impact how susceptible an individual is to infection by viral particles (72) and how far into the respiratory tract viral particles are likely to deposit (68). Decreased RH has been demonstrated to decrease mucociliary clearance of invading pathogens and weakened innate immune response (72–74). However, RH above 80% may begin to promote mold growth, inducing potentially detrimental health effects (75). Although the current ventilation standard adopted by health care and residential care facilities, ASHRAE 170-2017, permits a wider range of RH from 20% to 60%, maintaining a RH between 40% and 60% indoors may help to limit the spread and survival of SARS-CoV-2 within the BE, while minimizing the risk of mold growth and maintaining hydrated and intact mucosal barriers of human occupants (50, 67). Indoor humidification is not common in most HVAC system designs, largely due to equipment cost and maintenance concerns related to the risk of overhumidification increasing the potential of mold growth. While administrators and building operators should consider the costs, merits, and risks of implementing central humidification, especially during new construction or as a retrofit, it may be too time intensive to implement in response to a specific viral outbreak or episode. In addition, increased RH may lead to increased buildup on filters, decreasing airflow. However, in pandemic situations, this practice likely increases the effectiveness of capturing viral particles, and this benefit outweighs the increased filter maintenance required. Therefore, targeted in-room humidification is another option to consider, and this may reduce the likelihood of a maintenance oversight causing overhumidification. Building ventilation source and distribution path length can affect the composition
Precautions our company will be taking to protect your employees as well as your customers.
1. PDI will be asking how our employee feels each day.
2. PDI will have employee’s take temperatures each day before their respective shifts.
3. PDI will ask employee if they have had potential exposure to Covid-19.
4. PDI will be issuing PPE to our employees.
5. PDI will perform any sort of Covid-19 testing on employees when they become available from our government.