Air Purifier for Traffic Pollution
With traffic pollution, you are dealing with particulate and gases that need to be filtered out by an air purifier.
The exhaust 'particulates' are tiny specks of soot that are so small you can not actually see them individually. Many of these particles can be trapped inside the HEPA filter found in most common air purifiers these days The second type of pollutant is ‘gases’, such as Nitrogen Dioxide cannot be trapped in a HEPA filter. Gases are so small they fly straight through any HEPA filter completely unimpeded.
What type of Air Purifier is needed for Traffic Pollution?
In order to be certain of also removing the gases you need to ensure that whichever air purifier you choose has not just got a HEPA filter inside but also an activated carbon filter. Activated carbon is the only type of filter that can adsorb the harmful gases and keep them locked away.
What size are the most common particles from traffic pollution?
Diesel exhausts are one the major sources of outdoor pollution. The particles sizes range from around 1 - 10 microns, with the largest volume being in the range up to 2.5 microns. You may often see traffic pollution referred to as PM2.5 in the media and on information relating to air quality monitors, filters and air purifiers.
PM2.5 relates to the particles with a diameter of 2.5 microns or less.
These type of particulates are also released into our air from such common sources as log burners, coal fires, and industrial processes. These particulates are the ones you are often able to see as 'haze' or 'smog' in big cities around the world.
Can an air purifier actually filter out traffic pollution particles?
The most common type of air purifier used to remove pollutants from traffic and other PM2.5 sources is one with a Hepa filter inside. The grey area however is that there are different ‘grades’ of Hepa filter. Although most of them are perfectly capable of filtering out particles as small as 0.3 microns which more than covers the troublesome PM2.5 category, some hepa filters are actually able to remove particles as small as 0.1 micron, meaning they remove much more of the even more hazardous pollutants missed by standard ones.
The HEPA filter is only part of the equation. Hepa filter does not deal with the gases, it only removes particles (PM2.5).
These harmful (usually odourless) gases need to be adsorbed as they come through the filter and before they re-enter the room. The only thing that will effectively do that is an activated carbon filter placed directly behind the HEPA filter. The type and size of the carbon is directly related to just how much of the pollution is adsorbed. Always try to choose a machine with actual activated carbon granules in the filter as opposed to a simple carbon impregnated sponge.
The 3 important considerations for Air Purifiers for Traffic Pollution are:
1. A good quality HEPA filter ( filtering to 0.1 micron if possible, but filtering to not 0.3 will still suffice )
2. An activated carbon filter ( Activated granular carbon not impregnated sponge).
3. Enough air volume to change the air around 5 times every hour in your room size.