# Air Pollution

Svante Arrhenius - 1896: CO2 content of the air influences the temperature of the atmosphere. 

Mary Rice Slides
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Wildfire

## Definitions
major pollutants: 

- particulate matter[PM] - subdivided by aerodynamic diameter less than __
- PM2.5 (associated with all cause mortality, acute CV and pulm mort. 2.5 = size that can make it to alveoli)
- 'Course particles' = PM 10 but not PM 2.5 (aka diam 2.5-10 micro m)
- 'Ultrafine particles' = PM 0.1 - passes through alv-blood barrier
- sulfur oxides (SO2)
- nitrogen oxides (NO2)- associated w incident asthma
- carbon monoxide (CO)
- volatile organic compounds aka reactive hydrocarbons
- lead
- Ambient Ozone (O3) - forms from NO2 and reactive hydrocarbons in atmosphere

High Efficacy particular air purifiers = filtration systems, do not remove ozone, nitrogen oxides . 

## Factors leading to disease

- clearance rate in the lungs (macrophage function and lymphatic system)
- immune system response (glutathione synthesis)

## Known adverse effects

Chest Summary 1 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904855/

Chest Summary 2 - (nonpulm) 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904854/

Harvard Six Cities Study


The Children’s Health Study:
evaluated yearly lung function during these two decades among more than 2,000 Southern California teenagers


A 13-month closure of a large steel mill in
the Utah Valley in the United States resulted
in a range of cardiopulmonary benefits.
When the steel mill was open, winter PM10
concentrations were twice as high as when
it was closed; hospital admissions for
pneumonia, pleurisy, bronchitis, and
asthma were greater, especially among
children, who had two to three times the
admission rates for these respiratory
conditions (35)

Associated with incident COPD but not asthma: https://www.atsjournals.org/doi/pdf/10.1164/rccm.202011-4168ED

## Indoor Air Pollution

Worldwide - major cause of morbidity and mortality. 3rd leading risk factor for burden of disease after hypertension and smoking. (Ambient air pollution is lower)

Coal, or biomass

Contributions: 

- poor ventilation, especially in cold areas
- disproportionate effect of women and childrens
- PM 10 go up to 1000-3000

Wood as primary or secondary heat source => how this still happens in the USA. 

Navajo nation - Shiprock has two coal plants outside of the normal regulation; provide the Navajo nation coal for free, which 25%+ burn in their homes. 


## Outdoor (ambient) Air Pollution

Criteria air pollutants - monitored under clean air act

Gaseous Polutants
Ground Level Ozone (ground level is different from stratospheric)
NO2
SO2
Lead
Carbon monoxide

Particulate matter
Sulfur-dioxides and nitrogen dioxides -> react to form small particulates. 
PM10
PM2.5

Wildfire smoke - mix of PM2.5 (mostly) but with other toxic oxidative and pro-inflammatory components that may be more toxic 
- one study suggested stronger associated with respiratory hospitalizations. 

AQI - includes ozone, PM, CO, SO2, NO2
AQI of 100 = NAAQS level for each pollutant. 
AQI of the day = highest point of the day.

Deaths per capita from air pollution: US among the highest.

General population: increased mortality, RTIs, lung cancer, new dx asthma, cardiovascular disease

Patients with increased susceptibility: asthma (exacerbations, lung function, poor control - 2.3% population attributable fraction.. probably higher in UT?), COPD (increased exacerbations, dec lung function, mortality both short and long-term), CF, IPF, Sarcoidosis (?), A1AT, Lung Transplant, CAD/CHF, DM, MH. 


What to do:

- unknown risk / benefit of foregoing activity in pollution, thus better to recommend to exercise indoors. Exercise early in the AM (ozone highest in afternoon)
- Air Filters: MERV (corresponds to size of particle it can grab - higher MERV->smaller min particle size). HEPA= filters at least 99.97% 0.3 micrometers or less.  Two options: portable or central (HVAC, 75% of houses have them. Needs sufficient run time - meaning if furnace is only intermittent operation it won't work well). Portable is better for asthma kids. Don't use plasma/ion air cleaners.
- masks - need to have tight seal. (e.g. N95)