Bracing for an exponential growth in passengers, Mineta San Jose Airport is proposing a robust plan to build a concourse with 14 new gates, a 330-room hotel and a 5,000-space parking garage.

But such development would spew a “significant and unavoidable” amount of ozone and greenhouse gases, according to a draft environmental report that’s undergoing public review. And all that pollution would conflict with the Bay Area Air Quality Management District’s 2017 Clean Air Plan.

At its Jan. 14 meeting, the San Jose City Council is expected to weigh the importance of accommodating anticipated passenger growth against dirtier skies, particularly during the construction phase, when it discusses proposed amendments to the master airport plan. It’s expected to vote on those amendments in the spring.

Officials from the Air Quality Management District say similar airport expansions that spawn pollution still have been approved in the past, but the Clean Air Plan aims to at least force officials to focus on how best to deal with the worst impacts, in this case from the increase in vehicle and airplane trips.

“If you didn’t take the increase of air traffic into effect, the other work could be offset with sustainability measures,” said Greg Nudd, deputy air pollution officer for policy at the Bay Area Clean Quality Management District. “A lot of people don’t realize how carbon-intensive flying is.”

The aviation industry accounts for 12 percent of all transportation-related greenhouse gas emissions and 3 percent of total greenhouse gas emissions in the United States, according to the Environmental Protection Agency.

From now until 2037, the city projects that the number of passengers using the airport annually will grow by more than 50 percent — from nearly 15 million to 22.5 million.

That explosion of service, which federal law says the airport and city cannot regulate or limit, will cause significant emissions of the greenhouse gas nitrous oxide and particulate matter of 10 micrometers or less in diameter, according to the environmental report.

Particulates — the air pollutant most harmful to the health of Bay Area residents — can cause a wide range of respiratory and cardiovascular problems, including strokes, heart attacks and premature deaths. Both greenhouse gases and particulates can contribute to global warming and climate change.

Some environmentalists suggest the city should focus on alternative modes of transportation rather than expanding the airport and encouraging more flying.

“The whole idea of expanding the airport right now — while we’re in a climate emergency — seems insincere,” said Katja Irving, co-chair of the Sierra Club Loma Prieta Chapter’s Conservation Committee. “You should be encouraging people to travel less and take the train rather than building more gates and making room for more flights.”

But according to airport officials, failing to develop the airport and provide more facilities would only create additional air quality issues.

“The need for air travel and the demand for air travel in San Jose is going to grow regardless of whether we build anything new or not,” said Scott Wintner, deputy director of marketing and communications. “But these projects will make the airport more efficient, so that planes are spending less time idling and waiting for a gate to open, which would only generate more emissions.”

In an effort to try limiting emissions during construction, the airport intends to prohibit equipment with diesel engines from idling more than two minutes, require that heavy off-road equipment meet high emission standards and instruct contractors to submit a “Construction Emissions Minimization Plan” to the city before beginning any work. It also plans to develop a “phased carbon management program” to track annual carbon emissions from the airport and identify reduction targets.

The environmental report examined five alternatives to the proposed development plans.

It deemed three of them infeasible — moving airport operations to Moffett Federal Airfield near Mountain View, relocating them to a new regional airport site or accommodating the increased demand at other Bay Area airports.

Two of the alternatives — not building any new airport facilities or sticking to the existing airport master plan — would not address the airport’s projected passenger demand, the report found.

“If you choke off the demand there, then people will just fly out of other airports,” Nudd said. “And the overall impact may be worse because if they live closer to the San Jose airport but instead they’re driving up to SFO or Oakland, then you may actually be making the problem worse by not increasing the capacity at San Jose.”

The airport currently consists of two terminals — A and B — with a total of 28 permanent gates and eight interim gates constructed over the last three years to serve its growth.

Under the proposed master plan amendments, 14 gates would be added to create a South Concourse connecting to Terminal B, replacing two surface parking lots and the eight interim gates and bringing the airport’s total number of gates to 42. Once completed, passengers will be able to walk the entire length of the airport terminals.

“It’s a puzzle,” Wintner said. “To build one thing, we have to reconfigure other things and build around existing facilities, all while maintaining the 24-7 operations of the airport today.”

Under the master plan amendments, the city plans to construct a 300,000-square-foot hotel with up to 330 guest rooms and 300 parking spaces across from the new Terminal B South Concourse and a new short-term parking garage with up to 5,000 parking spaces adjacent to the hotel.

The plan also outlines more than a dozen airfield upgrades to the runways and taxiways, construction of new cargo and general aviation facilities and the relocation of its belly-freight facilities.

Members of the public can submit comments on the draft environmental impact report to David Keyon in the city’s Department of Planning, Building and Code Enforcement at 408-535-7898 or via e-mail at David.Keyon@sanjoseca.gov until Jan. 13, 2020.