Air Quality Effects on Health

Air Pollution Part 1

• Air pollution is a mix of particles and gases reaching harmful concentrations indoors and outdoors.
• Exposure to air pollution is unavoidable and affects the entire population.
• Air pollutants are gases or particles in the atmosphere, linked to harming human health and the environment.
• Pollutants can be directly emitted (primary) or formed in the atmosphere (secondary).

Primary Pollutants

• Examples include CO, CO2, SO2, NOx, most hydrocarbons, and most suspended particles.

Secondary Pollutants

• Examples include HNO3, H2SO4, most NOx and SO2 salts.

Criteria Air Contaminants (CAC)

• A set of air pollutants (e.g., particulate matter [PM], sulfur dioxide [SO2], nitrogen oxides, volatile organic compounds [VOCs], carbon monoxide [CO], ozone [O3], and lead) causing smog, acid rain, and other health hazards.
• Primarily from fossil fuel combustion.

Burden of Illness

• Globally, 3.7 million deaths annually from outdoor air pollution.
• In Canada, 8800 deaths/year from PM2.5 and 680 from ozone.
• Outdoor air pollution and particulate matter are classified as carcinogens (Group 1) by the International Agency for Research on Cancer (IARC).
• Numerous adverse health effects, including asthma, respiratory illnesses, chronic obstructive pulmonary disease, cardiovascular disease, lung cancer, endocrine system effects, neurological effects, diabetes, allergies, and premature death.

Health Impacts of Air Pollution

• Impacts include various effects on the respiratory, cardiovascular, liver/spleen/blood, and reproductive systems. (e.g., headache, anxiety, breathing problems, irritation, inflammation, infections, asthma, reduced lung function, chronic obstructive pulmonary disease, lung cancer, cardiovascular diseases).

Environmental Burden of Cancer in Ontario

• Estimates the annual number of cancer cases (approximately 3,540–6,510) resulting from 23 environmental carcinogens.
• Key carcinogens include solar ultraviolet radiation (2,090–2,990 cases/year), radon (1,080–1,550 cases/year), and fine particulate matter (290–900 cases/year).

Particulate Matter (PM)

• A mixture of solid and liquid particles suspended in the air.
• Can be either primary (directly emitted) or secondary (formed from reactions with other pollutants).
• In Canada, open sources (like unpaved roads, construction) are the most common sources; wood-burning stoves are significant in Ontario.
• Categorized by size (aerodynamic diameter), with PM10 (≤10 µm), PM2.5 (≤2.5 µm), and total PM (≤100 µm).
• Fine particles cause more harm.

Sulfur Dioxide (SO2)

• Colourless, water-soluble gas with a sharp odour.
• Produced from the combustion of sulfur-containing fuels and materials (e.g., coal, metal ores).
• Can convert to sulfuric acid, contributing to acid rain, harming vegetation, buildings, and wildlife.
• Inhaled SO2 is absorbed by upper airway mucous membranes, but can penetrate deeper with increased ventilation.
• Health effects include reduced lung function, bronchoconstriction, respiratory symptoms, hospitalization, and death from cardiovascular and respiratory causes.
• Emissions decreased by 69% from 1990 to 2017.

Nitrogen Oxides (NOx)

• Category of highly-reactive gases containing nitrogen and oxygen (e.g., nitrogen dioxide, nitrogen oxide).
• Produced through combustion processes (heating, power generation, engines in vehicles and ships).
• In Ontario, transportation is the primary source (70%).
• Precursor to ground-level ozone and PM, contributing to acid rain.
• Health impacts include reduced lung function, eye, nose, and throat irritation, respiratory illness, and death.
• Emissions decreased by 26% from 1990 to 2017.

Volatile Organic Compounds (VOCs)

• Category of organic chemicals, evaporating readily.
• Sources include natural processes, industry, and transportation (anthropogenic).
• Urban areas heavily rely on anthropogenic sources.
• VOCs contribute to ground-level ozone and secondary PM formation.
• Many individual VOCs are toxic, causing respiratory tract irritation, headaches, cancer, and neurotoxicity.
• VOC emissions decreased by 40% from 1990 to 2017.

Carbon Monoxide (CO)

• Colorless, odorless, tasteless, and poisonous gas resulting from incomplete fossil fuel combustion.
• Outdoor exposure is highest near heavily trafficked streets and during temperature inversions (cold weather).
• Inhalation leads to carboxyhemoglobin formation, hindering oxygen transport; causing respiratory and circulatory problems.
• Widespread catalyst converter use in vehicles has reduced CO emissions in recent years.

Tropospheric Ozone (O3)

• Formed by complex chemical reactions involving VOCs and NOx in the presence of sunlight.
• Contributes to photochemical smog.
• Excessive levels can cause health problems (e.g., breathing problems, asthma, reduced lung function, respiratory diseases, and cardiorespiratory mortality).
• Can affect cognitive development and reproductive health, including preterm birth.
• Negatively impacts vegetation, crop production, and synthetic materials.

Smog

• A noxious mixture of gases and particles, often appearing as a haze.
• Primary pollutants and ground-level ozone/PM most commonly produce smog.
• Smog levels highest during summer due to sunlight and warmer temperatures; winter smog can also occur due to PM.

Urban Heat Island

• Urban areas tend to have higher surface and air temperatures compared to surrounding rural areas.
• Impacts air quality by increasing ground-level ozone formation and raising energy demand.
• Possible solutions include cool pavements, cool roofs, green roofs, and urban forestry to counteract this effect.

Lead

• Sources include ore processing, metal processing, aircraft using leaded aviation fuel, waste incinerators, utilities, and lead-acid battery manufacturers; smelters tend to be areas with greatest concentration.
• Emissions in Canada decreased drastically from 1990 to 2017 (86%), primarily from the closure of outdated smelters and pollution prevention plans enacted in 2006.
• Health issues depend on exposure levels, but they include nervous system, kidney, immune system, reproductive system, developmental system, and cardiovascular system issues. Lead affects oxygen-carrying capacity of the blood.

Case Study-Flint Water Crisis-2015

• Flint, Michigan, switched water sources to the Flint River in 2014 to save costs.
• This water was corrosive and caused massive lead contamination in the pipes.
• Lead levels exceeded safety guidelines in January 2015, and authorities acted slowly.
• High lead levels were linked to health issues (especially in children), outbreaks of Legionnaires' disease, and criminal charges against several state employees.
• A new water source was implemented in 2016, and Flint was subsequently reconnected to the Detroit water system.