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Compressed Air Contaminants | Air Compressor Guide
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Compressed Air Contaminants

Compressed air is an essential utility in various industries, from manufacturing to pharmaceuticals. However, the air quality within these systems is crucial, as contaminants can significantly impact production quality and equipment efficiency.

Contaminants in compressed air systems can come from various sources and can cause severe problems if not properly managed. The main categories of these contaminants are particles, water, oil, and microorganisms.

Types of Contaminants

Particles (dust)

These are solid impurities that may include dust, rust, or dirt that enters the system through intake or internal erosion of system components.

Particles such as dust and dirt usually enter the air system through the intake of the air compressor. These can originate from the ambient air and can include wear particles from the compressor itself. When these particles are not adequately filtered, they can cause abrasion and severe damage to air tools, pneumatic machinery, and product surfaces.

My first advice would be to install proper, quality air inlet filters on the suction side of your compressor.

Not only does it prevent dust in your compressed air. It will also save your compressor. Dust will wear down screw elements (screw-type compressor), wear down cylinders (reciprocating compressor), it will clog up oil separators, oil filters and compressed air filters.

So the best thing you can do: make sure dust can't get into your compressor in the first place!

The next thing you can do: install dust filters in the compressed air line. There are basically two places you can install dust filters: a big one near the compressor, or several small ones near the air consumers (machines, tools, etc).


Moisture is a common contaminant in compressed air systems. It can originate from the humidity in ambient air or from the compression process itself.

Water vapor and liquid water are typical in compressed air systems, but excess water can lead to corrosion of metal parts and piping, resulting in leaks and pressure drops.

It also poses a risk for microbial growth, which could compromise product purity in sensitive industries like food processing or pharmaceuticals.

For industries that require dry, clean air, such as pharmaceuticals and food processing, the presence of water can compromise product integrity.

More information on water in compressed air and how to get rid of it on our compressed air dryer page.


Oil in compressed air typically comes from lubricated compressors but can also come from vapors present in the ambient air. It is another common problem and often a result of bad maintenance.

Oil can degrade the quality of products, particularly in painting and food production environments. It can also damage air tools and systems by forming a sticky residue that attracts dirt and debris, which leads to further contamination.

On the other hand, oil in the air is often not even noticed or cared for, as many people don't care about a little oil in their compressed air, as it lubricates their air tools.

But, if there is a rise in the amount of oil in your system (today more oil than last month), there is something wrong. Something is changing.

Depending on the type of compressor you have, there could be something breaking down (like the oil separator in a screw compressor).

How to get rid of the oil? Install a compressed air oil filter. It will filter out most oil from the compressed air to get clean compressed air.

My advice: a little oil in the air is often not a problem, but keep an eye on the amount of oil. Also, if you need oil for lubrication of your air tools (grinders, cutters, etc) or other equipment, you should install a compressed air oiler, or an air line lubricator. It's a small device that you fill with oil and that you install near the machine that needs lubrication.

The lubricator will add a few drips of oil to the air every minute or hour (depends on what you want) to lubricate the equipment.


Microorganisms thrive in compressed air. Microbial contamination, including bacteria, viruses, and fungi, can also prosper in compressed air systems, especially where moisture exists.

These microorganisms are a serious concern in environments such as hospitals and food processing plants where sterility and hygiene are paramount.

That being said, outside medical, pharmaceutical and food related industries, microorganisms is usually not a big deal.

The Impact of Contaminants on Production

The presence of these contaminants can lead to several operational challenges. Product quality issues, increased

maintenance costs, downtime, and reduced efficiency are just some of the impacts businesses may face. Not meeting air quality standards as dictated by ISO 8573 and other regulations can result in failed inspections and non-compliance penalties, further emphasizing the importance of managing air purity.

Effective filtration and monitoring systems are pivotal to ensuring that the compressed air remains clean and safe for all intended uses. Regular checks and maintenance of air filtration systems can mitigate the risks posed by these contaminants, safeguarding both the products and the machinery used in production.

More Info

For more information about general air quality and whether you need it or not, visit our compressed air quality page.

Learn how to remove contaminants on our compressed air filters page.