Air Date: 3-8-2019|Episode 537
Dr. Azimi’s work came to our attention recently when we were sent a copy of a recent paper he worked on with Brent Stephens, PhD called “A framework for estimating the US mortality burden of fine particulate matter exposure attributable to indoor and outdoor microenvironments”. Dr. Stephens joined us on March 13, 2015 for a great show on The Intersection of Building Science, Energy Efficiency & IAQ.
Z-Man’s Blog:
Particulate matter kills, the mortality burden of fine particle exposure
Parham Azimi, PhD a research associate in the Dept. of Civil, Architectural and Environmental Engineering at Illinois Institute of Technology, was our guest on today’s episode of IAQradio. His research work is focused on fate, transport, and control of indoor aerosols of indoor and ambient origin, chronic health impacts of fine particles in various microenvironments, and energy performance of residential and commercial buildings.
After obtaining an undergrad degree in civil engineering he became interested in environmental engineering and obtained a masters’ degree. He came to the US seven years ago to pursue a doctorate degree. Having family in both Chicago and Boston he decided to look at doctorate programs in both cities. He decided to pursue his PhD with Brent Stephens at IIT. He is more interested in physics than chemistry,
Nuggets mined from today’s episode:
Parham hails from Iran. Iran is more than twice as big as Texas with a population of 80+ million. Iranian homes are made from concrete and steel. Due to concrete construction mold problems are rare. Iranian homes are either built above full basements or build on slabs, they don’t use crawl spaces.
When he was in Iran there was little awareness and knowledge about IAQ. This is changing, it’s now mandated that new construction projects in some newly developed cities (e.g. Sadra City, Fars, Iran) must consider IAQ and hire consultants.
Five years ago, he joined the ASHRAE 2.4, Particulate Air Contaminants and Particulate Contaminate Removal Equipment committee which focuses on particle contamination (both solid/liquid). Committee interests include: how to measure, how particles effect people and building materials, methods of removing particles, improving the efficiency and durability of AFDs. The committee is not purely focusedon toxicological aspects of particles.
In the lab custom designed experiments are performed to study AFDs (Air Filtration Devices). Particles can be injected into chambers and removal and efficiency rates of various AFDs compared. Fieldwork includes measurement and comparison of indoor and outdoor contaminate concentrations.
“Modeling the Impact of Residential HVAC Filtration on Indoor Particles of Outdoor Origin”
https://www.tandfonline.com/doi/abs/10.1080/23744731.2016.1163239
Have an ASHRAE grant to model the importance of HVAC filtration on contaminates of indoor and outdoor origin. High efficiency filters can reduce contaminates by 70%. In the field his team often encounters poor efficiency air filters. He attributes this to HVAC equipment manufacturers concerned about pressure drops specifying low efficiency filters. The lab also models the impacts of air filters with various MERV rating on the concentration of PM2.5 and UFPs.
Exhaust ventilation effects building pressurization while recirculating air does not.
The percentage of indoor particulate that originated outdoors depends on the type of home.
Smokers homes are not used for his studies.
One of his colleagues complained of headache after working in a room where printers were being used. This spurred interest in studying particle emission from printers. Laser printers and 3D printers both create particulate contamination. Depending on the type of printer, distance from printer, length of time printer is running, Parham has seen concentration of particles less than 100 nanometers (UFPs) which were regularly in the range of 8K-15K #/cm3 in a room increases to higher than 1,000,000 #/cm3 in his measurements. 3D printers in addition to particles also emit VOCs.
The most popular filaments used in 3D printers are either ABS (Acrylonitrile Butadiene Styrene) or PLA (polylactic acid). PLA is made from more natural or renewable (i.e. corn starch, tapioca roots, or sugarcane). 3D printers often run for hours. People sometimes watch them print for entertainment. Beware of unenclosed 3D printers! He’s not against using 3D printers he advocates a need for ventilation or a pollutant control system.
Laser cutters also emit particles and VOCs.
Parham and his colleague, Dr. Brent Stephens, introduced a framework for estimating the mortality rate associated with exposures to indoor and outdoor particulate matter in various microenvironments.
Epidemiological studies use census data to find a correlation between outdoor concentration of PM2.5 and numbers of deaths after accidental deaths are subtracted leaving deaths from heart, lung, cancer and other medical problems. Their results demonstrate a direct correlation between them. Based on this correlation they introduce a health endpoint estimate (beta value) for PM2.5.
In their framework, they used a modified version of health endpoint estimate to predict the total number of deaths in the US as well as in 9 different regions of the US based on the outdoor PM concentrations, home characteristics, and weather data. They also considered different microenvironments in their framework including outdoor environments and inside residences, other indoor environment (e.g. offices, schools, and restaurants), and vehicles. https://www.researchgate.net/publication/329433146_A_framework_for_estimating_the_US_mortality_burden_of_fine_particulate_matter_exposure_attributable_to_indoor_and_outdoor_microenvironments
90% of human exposure to particles occurs indoors. Also consider microenvironments and human exposure to PM 2.5. The model makes many assumptions for example the toxicity of indoor and outdoor origin particles are equal. Best estimate is that in 2015- 230,000 to 300,000 deaths are attributed to PM 2.5 in the U.S.
Most of exposure to particles from outdoor sources occurs indoors. Indoor exposure to outside origin particles is 40%-60% of total exposure to PM2.5. Uses 2 scenarios for applying model framework: Scenario 1 is the nationwide concentration. Scenario 2 is the regional concentration (9 regions). The modeling allows different packs of assumptions to be entered. Other researches can put more advanced assumptions in the framework and get new results.
The US air quality rates high when our PM 2.5 measurements are compared to other nations (India, China, etc.). India and China are often 10X higher than US. The air quality in other countries is sometimes so bad that schools are closed and people are told to stay indoors. Wildfires in the US increase PM 2.5 to Beijing levels temporarily.
To estimate the contribution of indoor and outdoor origin particles in indoor environments both modeling and measurements approaches can be taken. In the modeling approach, usually home characteristics such as penetration and air exchange rate, HVAC characteristics such as runtime and recirculation rate, and human activity patterns are considered in a mass balance equation which estimate how much air is entering the indoors from outdoors. In some studies the particle emission rates from indoor sources is considered as well. Based on these data the total concentration of particles is determined.
During field measurements to determine the contribution of outdoor origin particles in indoors, indoor sources are minimized as much as possible: homes are vacated, HVAC turned off, no cooking, etc. Indoors and outdoors are then measured and compared by passing information through a proper mass balance model.
Final comment on the study, where do we go from here? Be careful PM deaths are high, big money is spent yearly for medical related costs, reducing PM saves money. WE must do more to control PM and other air pollutants.
Post Doc HUD study. 41 homes are being studied. 3 different ventilation systems are being installed in the homes: 1) Continuous exhaust only, 2) System which introduces fresh filtered air into the HVAC (i.e. Central Fan Integrated Ventilation System, which is intermittent) and 3) Fully ducted ventilation system with an ERV. The fully ducted ERV system moderates harsh extremes in temperature. The program provides replacement filters. The homes are studied 1 year prior to equipment installation and 1 year after equipment installation and differences measured (IAQ and asthma). Status report: just completed equipment installation and visited the first 10 homes after installing the ventilation systems.
Final comment:
He is happy awareness of and attention to IAQ is improving.
He also wants to thank his research sponsors. The PM2.5 mortality study was supported by the US Environmental Protection Agency, Office of Radiation and Indoor Air, Indoor Environments Division, in collaboration with the Scientific Consulting Group. His research on other areas was also supported by several organizations including ASHRAE, NIOSH, and Department of Housing and Urban Development (HUD) during his Ph.D. education and Post-doc fellowship.
Z-Man signing off
Trivia question:
Name the legislation and the year it was passed that created a research and regulatory program in the U.S. Public Health Service?
Answer:
Clean Air Act of 1963
