Question

An average adult breathes about \(8.50 \times 10^{3} \mathrm{~L}\) of air per day. The concentration of lead in highly polluted urban air is \(7.0 \times 10^{-6} \mathrm{~g}\) of lead per one \(\mathrm{m}^{3}\) of air. Assume that \(75 \%\) of the lead is present as particles less than \(1.0 \times 10^{-6} \mathrm{~m}\) in diameter, and that \(50 \%\) of the particles below that size are retained in the lungs. Calculate the mass of lead absorbed in this manner in 1 year by an average adult living in this environment.

Short answer

Answer: The mass of lead absorbed in one year by an average adult living in this environment is approximately \(8.14 \times 10^{-3} \mathrm{~g}\).

Step-by-step solution

Calculate the volume of air breathed in one day

An average adult breathes about \(8.50 \times 10^{3} \mathrm{~L}\) of air per day.

Convert the volume of air to the required unit (cubic meters)

To convert the volume of air from liters to cubic meters, we use the following conversion: 1 cubic meter (m³) = 1000 liters (L) So, the volume of air breathed in one day in cubic meters is: \(\frac{8.50 \times 10^{3} \mathrm{~L}}{1000 \mathrm{~L/m^{3}}} = 8.50 \mathrm{~m^{3}}\)

Calculate the mass of lead present in that volume using the given concentration

The concentration of lead in highly polluted urban air is \(7.0 \times 10^{-6} \mathrm{~g/m^{3}}\). Therefore, the mass of lead present in \(8.50 \mathrm{~m^{3}}\) of air is: \(8.50 \mathrm{~m^{3}} \times 7.0 \times 10^{-6} \mathrm{~g/m^{3}} = 5.95 \times 10^{-5} \mathrm{~g}\)

Calculate the amount of lead in particles small enough to be inhaled

\(75 \%\) of the lead is present as particles less than \(1.0 \times 10^{-6} \mathrm{~m}\) in diameter. So, the mass of lead in inhalable particles is: \(5.95 \times 10^{-5} \mathrm{~g} \times 0.75 = 4.46 \times 10^{-5} \mathrm{~g}\)

Calculate the amount of lead retained in the lungs

\(50 \%\) of the particles below the specified size are retained in the lungs. So, the mass of lead retained in the lungs per day is: \(4.46 \times 10^{-5} \mathrm{~g} \times 0.50 = 2.23 \times 10^{-5} \mathrm{~g}\)

Convert the lead absorption per day into a yearly value

To find the mass of lead absorbed in one year, multiply the daily absorption by the number of days in a year: \(2.23 \times 10^{-5} \mathrm{~g} \times 365 \mathrm{~days} = 8.14 \times 10^{-3} \mathrm{~g}\) So, the mass of lead absorbed in this manner in 1 year by an average adult living in this environment is approximately \(8.14 \times 10^{-3} \mathrm{~g}\).

Key concepts

Understanding Air Pollution

Air pollution refers to the presence of harmful substances in the atmosphere, which can pose serious health and environmental risks. It includes a wide range of pollutants, such as gases, particulate matter, and heavy metals, like lead. Pollution levels are measured to help us understand the concentration of these contaminants in the air we breathe on a daily basis.

Specifically, by monitoring air pollution, we can gauge the quality of the air, enact policies to minimize emissions, and safeguard public health. The exercise from the textbook highlights the process of calculating the concentration of lead, a common air pollutant, to assess the potential health impact on an individual from exposure to polluted air in urban areas.

Risks of Lead Exposure

Lead exposure is a significant health concern, particularly in areas with high levels of air pollution. Even at low levels of exposure, lead can cause a variety of adverse health effects. It is particularly dangerous for children, as it can affect their developing brains, leading to cognitive deficits and behavioral problems.

Adults are not safe either; lead exposure can result in cardiovascular issues, decreased kidney function, and reproductive problems. By understanding how lead exposure occurs through air pollution, individuals and communities can take steps to mitigate exposure and its associated risks, emphasizing the importance of calculations like those in our textbook exercise.

Stoichiometry: A Tool for Environmental Health

Stoichiometry is the field of chemistry that involves calculating the amounts of reactants and products in chemical reactions. It is also a crucial tool in environmental chemistry for quantifying pollution levels and potential exposure, as demonstrated in the textbook exercise. The exercise employed stoichiometry to determine the mass of lead an average adult would absorb over the course of a year, considering the concentration of lead in the air and the volume of air breathed.

To simplify stoichiometric calculations:

• Start with known quantities and units.
• Apply conversion factors to change units if necessary.
• Use percentages to determine proportions of interest, such as the amount of lead retained in the lungs.

Clear and correct stoichiometric calculations are essential in environmental health for providing data that supports regulations and protective measures against toxic exposures like lead.