HVAC Systems with David Tomsey

With over eighteen years of experience in environmental, health, and safety consulting, David runs Emilcott’s Indoor Environmental Quality practice. He was one of the original leaders who developed our proprietary Greenlight system for real-time air monitoring on construction sites. His experience includes performing hazardous materials surveys, perimeter air monitoring system development and implementation, remedial investigations; performing soil and water investigations, and survey design.

What is an HVAC system? How does it work?

An HVAC system cleans air through a series of filters. This means it basically circulates air through a building to provide comfort to all occupants. Comfort can be thermal (through heat) as well as through cool air. Simply put, it is an air exchange system regulating temperature and contaminants that can be found in the air of an indoor space.

HVAC systems remove moisture all year-round, but they are especially important during the summer months. Without an HVAC system, excessive moisture creates an environment for mold growth.

What is the importance of a clean HVAC system?

As people return to work, it is important to do a deep cleaning of buildings’ HVAC systems, especially those turned off during the past few months.

The Minimum Efficiency Reporting Value, also known as MERV, is a measurement scale used for tracking the effectiveness of air filters. Typically, it has been recommended that a building’s MERV number is an 8 or 9. But since the emergence of the coronavirus, the recommended MERV number is now 13 to prevent viruses from forming in the air space.

A lot of buildings will shut their systems down overnight but typically not when temperatures are high outside. It is now recommended that all places keep their HVAC Systems running 24/7 for a greater air exchange rate. Usually, the system is responsible for just filtering indoor air. In today’s world, it is wise to bring in the outdoor air and kill the virus with heat and sunlight.

What issues arise when HVAC systems are not taken care of?

When HVAC systems are not cleaned and used properly, there is a greater chance that indoor aerosols are lingering for a longer amount of time.

Dirt and debris (when not eliminated from the air) harbor environments for bacteria and viruses. A well-functioning system reduces airborne concentrations of viruses.

A properly operated system helps individuals fight colds, flus, and viruses. With the correct amount of humidity in the air, the human body is operating in optimal circumstances. Otherwise, our bodies have to work a lot harder to keep us healthy.

How do you know when you need help?

Buildings that need this type of service include office and retail spaces, healthcare facilities, hospitals, and hotels, among other types of public places. When someone comes to help you with this issue, they should test for general indoor parameters, particulates, dust, and volatile organic compounds (VOCs.) They will also want to ensure there are no issues with odors or allergic reactions as systems are put to use. This type of testing gives clients an understanding of the state of their indoor space.

Emilcott works with other people in order to evaluate the HVAC system at hand. If it is found that people are having issues with odors or allergic reactions, Emilcott can come and investigate.

If you have questions about your HVAC system or any Emilcott services, call us at 800-866-3645 or email us at

Understanding Your Ventilation System

By: Allen M. Chung, CIH and Paul Linnartz

As people start to return to office buildings and public areas after more than a year of “pandemic life,” there will undoubtedly be a heightened awareness of air quality in closed spaces.

Certain viruses, such as SARS-CoV-2, are known to spread through aerosolized respiratory droplets at close range. Airborne transmission from exposure to tiny droplets is unlikely over long distances but possible in certain indoor spaces. General ventilation typically addresses common contaminants often found in commercial environments, but many commercial systems have not been designed to protect occupants from contagions like the SARS virus. Therefore, understanding a facility’s general ventilation system is an essential step toward improving indoor air quality (IAQ) as well as moderating the risk of spreading disease at your facility.

To help you moderate the spread of contagious diseases in an indoor space, the National Center for Biotechnology Information (NCBI) published an article that recommends the following:

  • increasing air exchange rates above current conditions
  • using high‐efficiency filtration for recirculated air (MERV 13 or higher)
  • verifying that sensitive areas, such as bathrooms and rooms where infected patients are cared for in hospitals and senior homes, are negatively pressurized relative to adjacent areas
  • managing airflow direction and speed to prevent the spread of aerosols across occupants
  • considering additional technological controls, such as UV germicidal irradiation and portable air purification, in areas and situations where typical building‐level controls are not sufficient

Ventilation effectiveness is measured in terms of Air Changes per Hour (ACH). By running the recirculated air through high-efficiency filtration (MERV 13 or higher), possibly adding UV germicidal irradiation and portable air purification units, more “clean” air is provided to the indoor space. The amount of clean air needed can vary widely depending upon building design and occupancy. ASHRAE, which sets ventilation standards and guidelines, recommends ACH levels up to 3x/hr for offices, 6x/hr for schools, and 8x/hr for restaurants.

Do you know what your ACH rate is?

Evaluating air exchange rates (ACH), checking negative pressure at sensitive areas, and mapping airflow direction and speed in your facility can determine whether your ventilation systems promote healthy indoor environmental conditions. This can be a complicated process.  If Emilcott can be of any assistance, reach out to

Summertime IAQ Checklist

June is National Safety Month! For 25 years, the National Safety Council (NSC) has been celebrating National Safety Month as an annual reminder to “keep each other safe from the workplace to anyplace.”

The topic for this week is: Address Ongoing COVID-19 Safety Concerns.

Public spaces are preparing their returns to normal operation as we finally turn the corner on this pandemic. After a year of reduced capacities and heightened awareness of air quality in closed spaces, property managers need to make sure their air handling maintenance is ready.

Using our 30 years of experience with indoor air quality, Emilcott has compiled a checklist to help you verify that your building’s air quality is in peak shape for summer openings.

6 IAQ Tips for Buildings at Risk of Having Poor Air Quality

Are your building occupants complaining of symptoms like itchy eyes, coughs, allergies, and headaches? Have you noticed a persistent and unusual odor in your building lately? You’d be surprised at how common it is to have poor indoor air quality—and how often it is caused by a distinct source with an easy fix. In our 30 years of air quality testing, we’ve seen all kinds of problems due to poor air handling maintenance: from HVAC filters that haven’t been changed in years to pigeons roosting near the air intake and leaving feathers and droppings to forgotten insulation and trash inside the AHU after a contracting job. These problems are not unusual, and they’re not going away.

Air quality concerns and problems aren’t going away either. In fact, they seem to be on the rise, especially with growing reports of poor outdoor air quality across the globe.

To mitigate these growing concerns, we’ve compiled 6 important air quality tips that we recommend all property managers consider when building issues arise:

#1: Confirm adequate ventilation and airflow. When evaluating operations and activities in the building, are functions and spaces properly located and ventilated? For example, printers can often give off fire particulates, and kitchenettes and bathroom exhausts can create unpleasant odors. Making sure adequate ventilation and airflow are present relative to the purpose of the space can go a long way toward staving off complaints.

#2: Revisit your building’s cleaning services. Are the building cleaning schedules adequate? How frequently are you preventing dirt from entering the building at the doors and windows? Does the housekeeping schedule provide adequate removal of dust and particulates? Do they vacuum the carpets and dust the shelves with regularity? Simple spot checks on these services can often provide clues as to the efficacy of cleaning services.

#3: Create a water intrusion policy. Do you have a formal policy or procedure for responding to water intrusion? Timely and appropriate response (within 24-48 hours) can eliminate the potential for mold. Be specific in your plan and consider differences in policies, procedures, and timing regarding the source of the water intrusion (e.g., rainwater vs. toilet backup.)

#4: Develop a procedure for complaints. Do you have a standard operating procedure for responding to complaints? When a complaint occurs from a building occupant or a visitor, do you have a standard operating procedure for investigating and responding to the complaint? Often when complaints are ignored, there can be the perception that building air quality has worsened because no one is actively managing it…so make sure that you are proactively managing it!

#5: Maintain your HVAC filters. Have the HVAC filters been regularly and properly maintained? Filters must be changed on an appropriate schedule. We have found that even filters that have been changed quarterly create the potential for dust-related allergies and/or bacterial and fungal growth, which can aggressively impact building occupants. And remember – not all filters are the same so it is important you use filters that are of good quality.

#6: Visit the air handler. When was the last time you visited the air handler? Beyond filters, consider checking that water and dust are not accumulating inside the air handler. The entire AHU from outdoor air intake to discharge into the building, supply ducts, and return ducts all warrant inspection to identify problems.

So what do you do if you find you have a more serious air quality problem? Indoor air quality should always be evaluated relative to outdoor air quality. If outdoor air quality is good, increasing ventilation may be sufficient. However, when outdoor air quality is an issue, active management of air inside the building envelope is critical.

In an age where air quality is increasingly challenging to manage, proactive measurement and maintenance of indoor air quality – as suggested in our 6 tips above – can be critical to maintaining employee health and wellness.

Spring Cleaning: What About Your HVAC System?

Indoor air quality complaints from employees can be quite common in office environments.  Symptoms such as red or itching eyes, cough, colds, allergies, headaches and unusual odors are some of the issues that can be reported by building occupants.  In the course of investigating contributing causes, a review of the buildings use history, inspection of the immediate complaint area and measurement of various airborne contaminants may not reveal a likely source.  This is when a trip to the air handling unit (AHU) on the roof becomes necessary.

Protection Against Legionella

As of November 13, 2015, all owners and operators of cooling towers in New York must abide by New York State Department of Health (DOH) regulations concerning operation and maintenance of cooling towers, evaporative condensers or fluid coolers.  The regulation was implemented to aid in the control of Legionella and are intended to minimize potential exposures to the public who live and work near cooling towers and equipment.  This regulation requires registration and periodic reporting, testing, inspection, and certification.

Crystalline Silica and Silicosis

Silicosis is a potentially dangerous but preventable occupational lung infection caused by inhaling respirable particles containing crystalline silicon dioxide (silica). Quartz, a form of crystalline silica, is the second-most plentiful mineral inside the earth’s crust. 

Volatile Organic Compounds (VOCs) in the Indoor Environment

VOCS: volatile organic compounds, or VOCs, are carbon-containing organic chemicals—many of which can be present in indoor in low concentrations. Indoor sources include building materials, furnishings, consumer products, tobacco smoke, and indoor chemical reactions (spontaneous chemical reactions between oxidants such as ozone and various common indoor chemicals in indoor air or on indoor surfaces). VOCs from attached buildings such as auto repair shops and dry cleaners may also enter indoor living spaces, as can outdoor air, also a source of pollutants containing VOCs. VOCs may be odorous and some VOCs are known or suspected to cause a variety of adverse health effects.

Industrial Ventilation in the Work Environment

Uncontaminated air is anticipated in the present industrial work environment. The utilization of chemical compounds, a lot of that are extremely dangerous, can result in concentrations that approach or exceed exposure limits in particulate, fumes, mists or vapors.

Also, excessive heat will make a work environment uncomfortable and dangerous. Successful properly-created industrial ventilation methods could reduce the hazards produced problems and by these chemical.