Airborne risks of disinfecting

Safety first

Personnel and student safety are of paramount importance. When implemented in a comprehensive decontamination program, foggers are best used after a physical cleaning that is designed to remove both dirt and biofilms.
Most sprayers and foggers have large particle sizes that weigh quite a lot. Due to gravity, these particles fall down through the air in seconds. Because the particles are so large, they do not travel well into nooks and crannies or discrete areas where bacteria and viruses can survive for long periods of time. The use of electrostatic ULV foggers creates much smaller particles in the 50-10 micron range. These particles wrap more effectively around corners and underneath surfaces and their coverage is far superb to the use of sprayer-sized particles. They use far less disinfectant, have a lower chemical impact on the environment, and leave about 80% less chemical residue behind.
These smaller-sized particles float in the air and stay suspended for much longer periods of time than sprayer-sized particles. It is the increased amount of airborne time that is pivotal to the particles’ heightened efficacy in traveling to remote places and into smaller nooks and crannies and discrete areas.

Particle sizes

To understand the risk of inhalation of these particles after a treatment, it is important to understand the particle sizes and the amount of time that they stay airborne, resisting gravity. For reference, a drop of water is roughly 800 microns. Sprayers emit about 200 micron particles and foggers emit about 100-50 micron particles. True ULV foggers emit 50-10 micron particles. It is the ULV fogger’s smaller micron size that makes them so effective. We’ve all seen how fast a drop of water falls to the floor. Any of us that have used a trigger sprayer might have noticed that these smaller particles fall a little slower--that’s the range of a sprayer. Fogger-sized particles in the 100-60 micron range will stay airborne for about 4 seconds when sprayed at about 5 ft above the ground. A true ULV fogger emits 50-10 microns sized particles.

50 micron sized particles sprayed at 5ft in the air will stay airborne for approximately 5 seconds
40 micron particles will stay airborne for approximately 8 seconds
30 micron particles will stay airborne for approximately 12 seconds
20 microns will stay airborne for approximately 24 seconds
10 microns will stay airborne for approximately 1 minute

As an example, the airflow created by a Sani-fogger can increase how long all of these particles stay in the air by 2-3x. This helps to provide greater coverage and increase coverage efficiency times. To address the smallest particles that stay airborne the longest, we’re looking at a maximum of a 3-minute period of time until the particles fall to the ground. Operators are trained to fog their way out of a home, school, or office, and this includes fogging their way out of vehicles or busses to minimize their exposure. They are directed to wear protective masks suitable for the chemical they are using.

After an area is treated, it is closed up and confined for 10 minutes to ensure that the chemistry has time to do its job of sanitizing or disinfecting. The 10 minutes serves two purposes: first, it provides a 3-4x safety factor for particles to drop, and second, after 10 minutes, even with internal air currents, there are not particles large enough in the air or concentrations great enough to affect even the most sensitive people as everything has had ample time to fall to the floor. Additionally, please bear in mind that as soon as doors or windows are opened, an air exchange occurs, replacing indoor air with outdoor air in as little as 1-2 minutes.

ULV electrostatic fogging with a Sani-fogger is icing on the cake of a really comprehensive decontamination procedure, and facilitates the greatest possible efficacy of COVID and other viral agent eliminators.

The topic of disinfectant particles